diff --git a/src/dds.imageio/ddsinput.cpp b/src/dds.imageio/ddsinput.cpp
index 8b4ba441b2..7825bcb911 100644
--- a/src/dds.imageio/ddsinput.cpp
+++ b/src/dds.imageio/ddsinput.cpp
@@ -796,6 +796,10 @@ DDSInput::seek_subimage(int subimage, int miplevel)
 
     m_subimage = subimage;
     m_miplevel = miplevel;
+
+    if ((m_dds.flags & DDS_MIPMAPCOUNT) && (int)m_dds.mipmaps > 1)
+        m_spec.attribute("oiio:miplevels", (int)m_dds.mipmaps);
+
     return true;
 }
 
diff --git a/src/doc/builtinplugins.md b/src/doc/builtinplugins.md
index 89e5709a34..8c56643a5a 100644
--- a/src/doc/builtinplugins.md
+++ b/src/doc/builtinplugins.md
@@ -184,6 +184,10 @@ red & green channels).
      - string
      - For environment maps, which cube faces are present (e.g., ``"+x -x
        +y -y"`` if *x* & *y* faces are present, but not *z*).
+   * - ``oiio:miplevels``
+     - int
+     - The number of MIP levels, only for MIP-mapped files with more than
+       one level.
 
 ```
 
@@ -1660,6 +1664,10 @@ The official OpenEXR site is <http://www.openexr.com/>.
    * - ``oiio:subimages``
      - int
      - The number of "parts" (subimages) in the file.
+   * - ``oiio:miplevels``
+     - int
+     - The number of MIP levels of the part (subimage), only for MIP-mapped
+       parts with more than one level.
    * - ``smpte:TimeCode``
      - int[2]
      - SMPTE time code (vecsemantics will be marked as TIMECODE)
@@ -2271,6 +2279,10 @@ Ptex files at all.
    * - ``wrapmode``
      - string
      - the wrap mode as specified by the Ptex file.
+   * - ``oiio:miplevels``
+     - int
+     - The number of MIP levels of the face (subimage), only when the face
+       has more than one level.
    * - *other*
      -
      - Any other arbitrary metadata in the Ptex file will be stored directly
diff --git a/src/doc/stdmetadata.md b/src/doc/stdmetadata.md
index af4c52fd48..d7903366a4 100644
--- a/src/doc/stdmetadata.md
+++ b/src/doc/stdmetadata.md
@@ -174,6 +174,14 @@ OpenImageIO understands.
     to find out how many there are.
 ```
 
+```{eval-rst}
+.. option:: "oiio:miplevels" : int
+
+    The number of MIP levels of the subimage, only present for images
+    stored in a MIP-mapped layout with more than one MIP level, and absent
+    for non-MIP-mapped images.
+```
+
 ```{eval-rst}
 .. option:: "oiio:SourcePath" : string
             "oiio:SourceFileFormat" : string
diff --git a/src/include/OpenImageIO/imagebuf.h b/src/include/OpenImageIO/imagebuf.h
index f532f9dc08..b4611da302 100644
--- a/src/include/OpenImageIO/imagebuf.h
+++ b/src/include/OpenImageIO/imagebuf.h
@@ -1267,7 +1267,8 @@ class OIIO_API ImageBuf {
     /// Return the number of MIP levels of the current subimage within the
     /// file this ImageBuf refers to. This will always be 1 for an ImageBuf
     /// that was not constructed as a direct reference to a file, or if this
-    /// subimage within the file was not MIP-mapped.
+    /// subimage within the file was not MIP-mapped. A return value of 0
+    /// indicates an error.
     int nmiplevels() const;
 
     /// Return the number of color channels in the image. This is equivalent
diff --git a/src/libOpenImageIO/imagebuf.cpp b/src/libOpenImageIO/imagebuf.cpp
index fbf06fdd42..8b3511beb1 100644
--- a/src/libOpenImageIO/imagebuf.cpp
+++ b/src/libOpenImageIO/imagebuf.cpp
@@ -565,6 +565,8 @@ ImageBufImpl::ImageBufImpl(const ImageBufImpl& src)
         m_nmiplevels       = 0;
         m_spec.erase_attribute("oiio:subimages");
         m_nativespec.erase_attribute("oiio:subimages");
+        m_spec.erase_attribute("oiio:miplevels");
+        m_nativespec.erase_attribute("oiio:miplevels");
         m_pixels_read = true;
     }
     if (src.m_configspec)
@@ -870,6 +872,7 @@ ImageBufImpl::clear()
     m_name.clear();
     m_fileformat.clear();
     m_nsubimages       = 0;
+    m_nmiplevels       = 0;
     m_current_subimage = -1;
     m_current_miplevel = -1;
     m_spec             = ImageSpec();
@@ -2109,7 +2112,18 @@ ImageBuf::miplevel() const
 int
 ImageBuf::nmiplevels() const
 {
-    m_impl->validate_spec();
+    if (!m_impl->validate_spec()) {
+        // Spec is invalid. Unnamed means no file to refer to (for example,
+        // default-constructed), so 1 as documented. Named means the file
+        // failed, so 0.
+        m_impl->m_nmiplevels = m_impl->m_name.empty() ? 1 : 0;
+    } else if (m_impl->m_name.empty() || m_impl->m_fileformat.empty()) {
+        // No direct reference to a file, so 1 as documented.
+        m_impl->m_nmiplevels = 1;
+    } else if (m_impl->m_nmiplevels == 0) {
+        m_impl->m_nmiplevels
+            = m_impl->m_spec.get_int_attribute("oiio:miplevels", 1);
+    }
     return m_impl->m_nmiplevels;
 }
 
@@ -2389,9 +2403,11 @@ ImageBuf::copy_pixels(const ImageBuf& src)
     m_impl->m_nsubimages       = 1;
     m_impl->m_current_subimage = 0;
     m_impl->m_current_miplevel = 0;
-    m_impl->m_nmiplevels       = 0;
+    m_impl->m_nmiplevels       = 1;
     m_impl->m_spec.erase_attribute("oiio:subimages");
     m_impl->m_nativespec.erase_attribute("oiio:subimages");
+    m_impl->m_spec.erase_attribute("oiio:miplevels");
+    m_impl->m_nativespec.erase_attribute("oiio:miplevels");
 
     return ok;
 }
diff --git a/src/openexr.imageio/exrinput.cpp b/src/openexr.imageio/exrinput.cpp
index 54464c7479..246cecaab3 100644
--- a/src/openexr.imageio/exrinput.cpp
+++ b/src/openexr.imageio/exrinput.cpp
@@ -422,8 +422,11 @@ OpenEXRInput::PartInfo::parse_header(OpenEXRInput* in,
 
     spec.deep = Strutil::istarts_with(header->type(), "deep");
 
-    if (levelmode != Imf::ONE_LEVEL)
+    if (levelmode != Imf::ONE_LEVEL) {
         spec.attribute("openexr:roundingmode", roundingmode);
+        if (nmiplevels > 1)
+            spec.attribute("oiio:miplevels", nmiplevels);
+    }
 
     const Imf::EnvmapAttribute* envmap;
     envmap = header->findTypedAttribute<Imf::EnvmapAttribute>("envmap");
@@ -1194,11 +1197,6 @@ OpenEXRInput::seek_subimage(int subimage, int miplevel)
     m_miplevel = miplevel;
     m_spec     = part.spec;
 
-    //! Add the number of miplevels as an attribute for the first miplevel.
-    //! TOFIX: adding the following attribute breaks unit tests
-    // if (m_miplevel == 0 && part.nmiplevels > 1)
-    //     m_spec.attribute("oiio:miplevels", part.nmiplevels);
-
     // The checks below reject this subimage. Invalidate rather than leave it
     // as the current one, or a repeat of this same seek would take the early
     // out above and hand back the spec we just refused.
diff --git a/src/openexr.imageio/exrinput_c.cpp b/src/openexr.imageio/exrinput_c.cpp
index 323385840a..2ebe8591c6 100644
--- a/src/openexr.imageio/exrinput_c.cpp
+++ b/src/openexr.imageio/exrinput_c.cpp
@@ -599,8 +599,11 @@ OpenEXRCoreInput::PartInfo::parse_header(OpenEXRCoreInput* in,
     spec.deep = (storage == EXR_STORAGE_DEEP_TILED
                  || storage == EXR_STORAGE_DEEP_SCANLINE);
 
-    if (levelmode != EXR_TILE_ONE_LEVEL)
+    if (levelmode != EXR_TILE_ONE_LEVEL) {
         spec.attribute("openexr:roundingmode", (int)roundingmode);
+        if (nmiplevels > 1)
+            spec.attribute("oiio:miplevels", nmiplevels);
+    }
 
     exr_envmap_t envmap;
     rv = exr_attr_get_envmap(ctxt, subimage, "envmap", &envmap);
@@ -1218,11 +1221,6 @@ OpenEXRCoreInput::seek_subimage(int subimage, int miplevel)
     m_miplevel = miplevel;
     m_spec     = part.spec;
 
-    //! Add the number of miplevels as an attribute for the first miplevel.
-    //! TOFIX: adding the following attribute breaks unit tests
-    // if (m_miplevel == 0 && part.nmiplevels > 1)
-    //     m_spec.attribute("oiio:miplevels", part.nmiplevels);
-
     // The checks below reject this subimage, so don't leave it as the
     // current one with a spec that failed validation.
     if (!check_open(m_spec, { 0, 1 << 30, 0, 1 << 30, 0, 1, 0, 1 << 12 })) {
diff --git a/src/tiff.imageio/tiffinput.cpp b/src/tiff.imageio/tiffinput.cpp
index d5cd7487a3..f3bdb4cb34 100644
--- a/src/tiff.imageio/tiffinput.cpp
+++ b/src/tiff.imageio/tiffinput.cpp
@@ -27,14 +27,12 @@
 
 // General TIFF information:
 // TIFF 6.0 spec:
-//     http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf
-// Other Adobe TIFF docs:
-//     http://partners.adobe.com/public/developer/tiff/index.html
+//     https://download.osgeo.org/libtiff/doc/TIFF6.pdf
 // Adobe extensions to allow 16 (and 24) bit float in TIFF (ugh, not on
 // their developer page, only on Chris Cox's web site?):
 //     http://chriscox.org/TIFFTN3d1.pdf
 // Libtiff:
-//     http://remotesensing.org/libtiff/
+//     http://www.simplesystems.org/libtiff/
 
 
 // clang-format off
@@ -1483,6 +1481,16 @@ TIFFInput::readspec(bool read_meta)
             m_spec.channelnames[c] = "z";
     }
 
+    // Set miplevels attribute in MIP emulation case (m_emulate_mipmap = true).
+    if (m_emulate_mipmap) {
+        // libtiff's TIFFNumberOfDirectories() returns tdir_t (uint32_t after
+        // libtiff v4.5.0, uint16_t before it), but the int cast seems safe for
+        // any realistic directory count here.
+        int nmiplevels = (int)TIFFNumberOfDirectories(m_tif);
+        if (nmiplevels > 1)
+            m_spec.attribute("oiio:miplevels", nmiplevels);
+    }
+
     /// read color profile
     unsigned int icc_datasize = 0;
     uint8_t* icc_buf          = NULL;
diff --git a/testsuite/dds/ref/out.txt b/testsuite/dds/ref/out.txt
index 0f21c60dfa..7c6d58434b 100644
--- a/testsuite/dds/ref/out.txt
+++ b/testsuite/dds/ref/out.txt
@@ -11,6 +11,7 @@ Reading ../oiio-images/dds/dds_bc1_mips.dds
     channel list: R, G, B, A
     compression: "DXT1"
     textureformat: "Plain Texture"
+    oiio:miplevels: 5
 Reading ../oiio-images/dds/dds_bc2.dds
 ../oiio-images/dds/dds_bc2.dds :   16 x    8, 4 channel, uint8 dds
     SHA-1: B458B3BAA7F457E06D04D0FBF93C003FFA729C97
@@ -74,6 +75,7 @@ Reading ../oiio-images/dds/dds_npot_bc3_mips.dds
     channel list: R, G, B, A
     compression: "DXT5"
     textureformat: "Plain Texture"
+    oiio:miplevels: 4
 Reading ../oiio-images/dds/dds_npot_rgba8.dds
 ../oiio-images/dds/dds_npot_rgba8.dds :   13 x    7, 4 channel, uint8 dds
     SHA-1: 6CBA3E2782498E2E92F5E4B08376A2E948FE3BAF
@@ -87,6 +89,7 @@ Reading ../oiio-images/dds/dds_npot_rgba8_mips.dds
     channel list: R, G, B, A
     textureformat: "Plain Texture"
     oiio:BitsPerSample: 32
+    oiio:miplevels: 4
 Reading ../oiio-images/dds/dds_r5g6b5.dds
 ../oiio-images/dds/dds_r5g6b5.dds :   16 x    8, 3 channel, uint8 dds
     SHA-1: 37A3BFD2B8A52006B4F07065A90BE774F276B751
@@ -118,6 +121,7 @@ Reading ../oiio-images/dds/dds_rgba8_mips.dds
     channel list: R, G, B, A
     textureformat: "Plain Texture"
     oiio:BitsPerSample: 32
+    oiio:miplevels: 5
 Reading ../oiio-images/dds/dds_a8.dds
 ../oiio-images/dds/dds_a8.dds :   24 x   20, 1 channel, uint8 dds
     SHA-1: 497ACCA96FAAC89AE74BDE8CA7B69B37CA9C5F20
@@ -283,6 +287,7 @@ src/crash-3950.dds   :   16 x    1, 4 channel, uint8 dds
     channel list: R, G, B, A
     compression: "DXT4"
     textureformat: "Plain Texture"
+    oiio:miplevels: 6
 oiiotool ERROR: read : "src/crash-bpp.dds": Invalid DDS bytes-per-pixel (322122548). Possible corrupt input?
 Full command line was:
 > oiiotool --info -v -a --hash src/crash-bpp.dds
diff --git a/testsuite/iinfo/ref/out-fmt6.txt b/testsuite/iinfo/ref/out-fmt6.txt
index 18f6417d72..f23197035c 100644
--- a/testsuite/iinfo/ref/out-fmt6.txt
+++ b/testsuite/iinfo/ref/out-fmt6.txt
@@ -18,6 +18,7 @@
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -441,6 +442,7 @@ src/mip.tif :    2 x    2, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25,0.5,0.75"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25,0.5,0.75"
+    oiio:miplevels: 2
     oiio:SHA-1: "1042D991FBDE596CF8FBC5660BC809AC057D8B9A"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
diff --git a/testsuite/iinfo/ref/out.txt b/testsuite/iinfo/ref/out.txt
index a40055176e..83ffe54599 100644
--- a/testsuite/iinfo/ref/out.txt
+++ b/testsuite/iinfo/ref/out.txt
@@ -18,6 +18,7 @@
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -442,6 +443,7 @@ src/mip.tif :    2 x    2, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25,0.5,0.75"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25,0.5,0.75"
+    oiio:miplevels: 2
     oiio:SHA-1: "1042D991FBDE596CF8FBC5660BC809AC057D8B9A"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
diff --git a/testsuite/maketx/ref/out-alt.txt b/testsuite/maketx/ref/out-alt.txt
index ab4b57c7ce..b6956f93a7 100644
--- a/testsuite/maketx/ref/out-alt.txt
+++ b/testsuite/maketx/ref/out-alt.txt
@@ -17,6 +17,7 @@ grid.tx              : 1000 x 1000, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "9B24D4CC05313A43973AC384718D81D19183B691"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -35,6 +36,7 @@ checker.tx           :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -54,6 +56,7 @@ checker.tx           :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -77,6 +80,7 @@ grid-resize.tx       : 1024 x 1024, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "2E23E9B4C6E707427A73B5433B23104D4183724E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -99,6 +103,7 @@ tahoe-resize.tx      :  512 x  512, 3 channel, uint8 tiff
     YResolution: 96
     oiio:AverageColor: "0.101931,0.216697,0.425473"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "799C1441E4B45378165DE450828109AF330A3F87"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -117,6 +122,7 @@ checker-uint16.tx    :  128 x  128, 4 channel, uint16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -135,6 +141,7 @@ checker-1chan.tx     :  128 x  128, 1 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "1D0A2254373A69C054C08672041FC7DE3BAE5179"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -153,6 +160,7 @@ checker-16x32tile.tx :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -171,6 +179,7 @@ checker-seplzw.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 5
     tiff:PhotometricInterpretation: 2
@@ -189,6 +198,7 @@ checker-clamp.tx     :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "clamp,clamp"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -207,6 +217,7 @@ checker-permir.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "periodic,mirror"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -244,6 +255,7 @@ checker-camera.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -262,6 +274,7 @@ checker-opaque.tx    :  128 x  128, 3 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "2BE3743A64D4309645F94CA7B37D0CD08AF0B38E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -281,6 +294,7 @@ gray-mono.tx         :  256 x  256, 1 channel, uint8 tiff
     oiio:AverageColor: "0.25098"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098"
+    oiio:miplevels: 9
     oiio:SHA-1: "24049CDF337F17E162291C7B626E0588A9D71160"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -300,6 +314,7 @@ pink-mono.tx         :  256 x  256, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25098,0.2,0.14902"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098,0.2,0.14902"
+    oiio:miplevels: 9
     oiio:SHA-1: "41B1A0D1C1EBB4CEEBC7BCEE2CAB2AAAB4139724"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -318,6 +333,7 @@ checker-prman.tx     :  128 x  128, 4 channel, int16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -365,6 +381,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -399,6 +416,7 @@ small.tx             :   64 x   64, 3 channel, uint8 tiff
     oiio:AverageColor: "1,0,0"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "1,0,0"
+    oiio:miplevels: 7
     oiio:SHA-1: "1DD1CB3C76F9A491B115F85A6DAC1B1A8DD2D3CB"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -458,6 +476,7 @@ bumpslope.exr        :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -548,6 +567,7 @@ bumpslope-central.exr :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00487623,0.00476811,-1.36547e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "E332A489C2BCDE63C2DB6A68E847CF396642F0A6"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -642,6 +662,7 @@ bumpslope-normal.exr :  128 x  128, 6 channel, half openexr
     version: 1
     wrapmodes: "black,black"
     oiio:AverageColor: "-1,-5.0059e-05,5.46902e-05,0.00489737,0.00494693,4.87366e-05"
+    oiio:miplevels: 8
     oiio:SHA-1: "BC210B60E71DDBBA147EAD3C638ACC908C11CF6C"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -744,6 +765,7 @@ cdf.exr              :   64 x   64, 1 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779"
+    oiio:miplevels: 7
     oiio:SHA-1: "00DFB31D0260CC466CDCF9FE42446D4896E655FE"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -776,6 +798,7 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -794,6 +817,7 @@ checker-attribs.tx   :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
diff --git a/testsuite/maketx/ref/out-macarm.txt b/testsuite/maketx/ref/out-macarm.txt
index 58204c8f4a..bc5cbdc9a9 100644
--- a/testsuite/maketx/ref/out-macarm.txt
+++ b/testsuite/maketx/ref/out-macarm.txt
@@ -17,6 +17,7 @@ grid.tx              : 1000 x 1000, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "9B24D4CC05313A43973AC384718D81D19183B691"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -35,6 +36,7 @@ checker.tx           :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -54,6 +56,7 @@ checker.tx           :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -77,6 +80,7 @@ grid-resize.tx       : 1024 x 1024, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "DBEF1FBDC368B03CAFEB8BEC0ACAB6C6E552817F"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -99,6 +103,7 @@ tahoe-resize.tx      :  512 x  512, 3 channel, uint8 tiff
     YResolution: 96
     oiio:AverageColor: "0.101931,0.216697,0.425473"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "0C3FC1C922FAEAB3F7A4EEB5DA101E54CA09CC2A"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -117,6 +122,7 @@ checker-uint16.tx    :  128 x  128, 4 channel, uint16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -135,6 +141,7 @@ checker-1chan.tx     :  128 x  128, 1 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "1D0A2254373A69C054C08672041FC7DE3BAE5179"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -153,6 +160,7 @@ checker-16x32tile.tx :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -171,6 +179,7 @@ checker-seplzw.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 5
     tiff:PhotometricInterpretation: 2
@@ -189,6 +198,7 @@ checker-clamp.tx     :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "clamp,clamp"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -207,6 +217,7 @@ checker-permir.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "periodic,mirror"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -244,6 +255,7 @@ checker-camera.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -262,6 +274,7 @@ checker-opaque.tx    :  128 x  128, 3 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "2BE3743A64D4309645F94CA7B37D0CD08AF0B38E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -281,6 +294,7 @@ gray-mono.tx         :  256 x  256, 1 channel, uint8 tiff
     oiio:AverageColor: "0.25098"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098"
+    oiio:miplevels: 9
     oiio:SHA-1: "24049CDF337F17E162291C7B626E0588A9D71160"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -300,6 +314,7 @@ pink-mono.tx         :  256 x  256, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25098,0.2,0.14902"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098,0.2,0.14902"
+    oiio:miplevels: 9
     oiio:SHA-1: "41B1A0D1C1EBB4CEEBC7BCEE2CAB2AAAB4139724"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -318,6 +333,7 @@ checker-prman.tx     :  128 x  128, 4 channel, int16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -365,6 +381,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -399,6 +416,7 @@ small.tx             :   64 x   64, 3 channel, uint8 tiff
     oiio:AverageColor: "1,0,0"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "1,0,0"
+    oiio:miplevels: 7
     oiio:SHA-1: "1DD1CB3C76F9A491B115F85A6DAC1B1A8DD2D3CB"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -458,6 +476,7 @@ bumpslope.exr        :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -548,6 +567,7 @@ bumpslope-central.exr :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00487623,0.00476811,-1.36547e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "E332A489C2BCDE63C2DB6A68E847CF396642F0A6"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -642,6 +662,7 @@ bumpslope-normal.exr :  128 x  128, 6 channel, half openexr
     version: 1
     wrapmodes: "black,black"
     oiio:AverageColor: "-1,-5.0059e-05,5.46902e-05,0.00489737,0.00494693,4.87366e-05"
+    oiio:miplevels: 8
     oiio:SHA-1: "BC210B60E71DDBBA147EAD3C638ACC908C11CF6C"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -744,6 +765,7 @@ cdf.exr              :   64 x   64, 1 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779"
+    oiio:miplevels: 7
     oiio:SHA-1: "00DFB31D0260CC466CDCF9FE42446D4896E655FE"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -776,6 +798,7 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -794,6 +817,7 @@ checker-attribs.tx   :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
diff --git a/testsuite/maketx/ref/out.txt b/testsuite/maketx/ref/out.txt
index c374695796..19df9fb547 100644
--- a/testsuite/maketx/ref/out.txt
+++ b/testsuite/maketx/ref/out.txt
@@ -17,6 +17,7 @@ grid.tx              : 1000 x 1000, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "9B24D4CC05313A43973AC384718D81D19183B691"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -35,6 +36,7 @@ checker.tx           :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -54,6 +56,7 @@ checker.tx           :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -77,6 +80,7 @@ grid-resize.tx       : 1024 x 1024, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "2E23E9B4C6E707427A73B5433B23104D4183724E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -99,6 +103,7 @@ tahoe-resize.tx      :  512 x  512, 3 channel, uint8 tiff
     YResolution: 96
     oiio:AverageColor: "0.101931,0.216697,0.425473"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "799C1441E4B45378165DE450828109AF330A3F87"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -117,6 +122,7 @@ checker-uint16.tx    :  128 x  128, 4 channel, uint16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -135,6 +141,7 @@ checker-1chan.tx     :  128 x  128, 1 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "1D0A2254373A69C054C08672041FC7DE3BAE5179"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -153,6 +160,7 @@ checker-16x32tile.tx :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -171,6 +179,7 @@ checker-seplzw.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 5
     tiff:PhotometricInterpretation: 2
@@ -189,6 +198,7 @@ checker-clamp.tx     :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "clamp,clamp"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -207,6 +217,7 @@ checker-permir.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "periodic,mirror"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -244,6 +255,7 @@ checker-camera.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -262,6 +274,7 @@ checker-opaque.tx    :  128 x  128, 3 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "2BE3743A64D4309645F94CA7B37D0CD08AF0B38E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -281,6 +294,7 @@ gray-mono.tx         :  256 x  256, 1 channel, uint8 tiff
     oiio:AverageColor: "0.25098"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098"
+    oiio:miplevels: 9
     oiio:SHA-1: "24049CDF337F17E162291C7B626E0588A9D71160"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -300,6 +314,7 @@ pink-mono.tx         :  256 x  256, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25098,0.2,0.14902"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098,0.2,0.14902"
+    oiio:miplevels: 9
     oiio:SHA-1: "41B1A0D1C1EBB4CEEBC7BCEE2CAB2AAAB4139724"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -318,6 +333,7 @@ checker-prman.tx     :  128 x  128, 4 channel, int16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -365,6 +381,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -399,6 +416,7 @@ small.tx             :   64 x   64, 3 channel, uint8 tiff
     oiio:AverageColor: "1,0,0"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "1,0,0"
+    oiio:miplevels: 7
     oiio:SHA-1: "1DD1CB3C76F9A491B115F85A6DAC1B1A8DD2D3CB"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -458,6 +476,7 @@ bumpslope.exr        :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -548,6 +567,7 @@ bumpslope-central.exr :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00487623,0.00476811,-1.36547e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "E332A489C2BCDE63C2DB6A68E847CF396642F0A6"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -642,6 +662,7 @@ bumpslope-normal.exr :  128 x  128, 6 channel, half openexr
     version: 1
     wrapmodes: "black,black"
     oiio:AverageColor: "-1,-5.0059e-05,5.46902e-05,0.00489737,0.00494693,4.87366e-05"
+    oiio:miplevels: 8
     oiio:SHA-1: "BC210B60E71DDBBA147EAD3C638ACC908C11CF6C"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -744,6 +765,7 @@ cdf.exr              :   64 x   64, 1 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779"
+    oiio:miplevels: 7
     oiio:SHA-1: "00DFB31D0260CC466CDCF9FE42446D4896E655FE"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -776,6 +798,7 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -794,6 +817,7 @@ checker-attribs.tx   :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
diff --git a/testsuite/oiiotool-maketx/ref/out-macarm.txt b/testsuite/oiiotool-maketx/ref/out-macarm.txt
index 5021cb4b2d..861a5fef58 100644
--- a/testsuite/oiiotool-maketx/ref/out-macarm.txt
+++ b/testsuite/oiiotool-maketx/ref/out-macarm.txt
@@ -17,6 +17,7 @@ grid.tx              : 1000 x 1000, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "9B24D4CC05313A43973AC384718D81D19183B691"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -40,6 +41,7 @@ grid-resize.tx       : 1024 x 1024, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "DBEF1FBDC368B03CAFEB8BEC0ACAB6C6E552817F"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -58,6 +60,7 @@ checker-uint16.tx    :  128 x  128, 4 channel, uint16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -76,6 +79,7 @@ checker-1chan.tx     :  128 x  128, 1 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "1D0A2254373A69C054C08672041FC7DE3BAE5179"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -94,6 +98,7 @@ checker-16x32tile.tx :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -112,6 +117,7 @@ checker-seplzw.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 5
     tiff:PhotometricInterpretation: 2
@@ -130,6 +136,7 @@ checker-clamp.tx     :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "clamp,clamp"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -148,6 +155,7 @@ checker-permir.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "periodic,mirror"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -185,6 +193,7 @@ checker-camera.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -203,6 +212,7 @@ checker-opaque.tx    :  128 x  128, 3 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "2BE3743A64D4309645F94CA7B37D0CD08AF0B38E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -222,6 +232,7 @@ gray-mono.tx         :  256 x  256, 1 channel, uint8 tiff
     oiio:AverageColor: "0.25098"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098"
+    oiio:miplevels: 9
     oiio:SHA-1: "24049CDF337F17E162291C7B626E0588A9D71160"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -241,6 +252,7 @@ pink-mono.tx         :  256 x  256, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25098,0.2,0.14902"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098,0.2,0.14902"
+    oiio:miplevels: 9
     oiio:SHA-1: "41B1A0D1C1EBB4CEEBC7BCEE2CAB2AAAB4139724"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -259,6 +271,7 @@ checker-prman.tx     :  128 x  128, 4 channel, int16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -307,6 +320,7 @@ bigval.exr           :    2 x    2, 3 channel, half openexr
     wrapmodes: "black,black"
     oiio:AverageColor: "1e+06,1e+06,1e+06"
     oiio:ConstantColor: "1e+06,1e+06,1e+06"
+    oiio:miplevels: 2
     oiio:SHA-1: "E3D97EED7EE68F1885685F312DDD7D8773C29862"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -349,6 +363,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -389,6 +404,7 @@ small.tx             :   64 x   64, 3 channel, uint8 tiff
     oiio:AverageColor: "1,0,0"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "1,0,0"
+    oiio:miplevels: 7
     oiio:SHA-1: "1DD1CB3C76F9A491B115F85A6DAC1B1A8DD2D3CB"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -599,6 +615,7 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
diff --git a/testsuite/oiiotool-maketx/ref/out-rhel7.txt b/testsuite/oiiotool-maketx/ref/out-rhel7.txt
index ce2a6b0d28..4b1ed75d53 100644
--- a/testsuite/oiiotool-maketx/ref/out-rhel7.txt
+++ b/testsuite/oiiotool-maketx/ref/out-rhel7.txt
@@ -17,6 +17,7 @@ grid.tx              : 1000 x 1000, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "9B24D4CC05313A43973AC384718D81D19183B691"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -40,6 +41,7 @@ grid-resize.tx       : 1024 x 1024, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "2E23E9B4C6E707427A73B5433B23104D4183724E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -58,6 +60,7 @@ checker-uint16.tx    :  128 x  128, 4 channel, uint16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -76,6 +79,7 @@ checker-1chan.tx     :  128 x  128, 1 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "1D0A2254373A69C054C08672041FC7DE3BAE5179"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -94,6 +98,7 @@ checker-16x32tile.tx :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -112,6 +117,7 @@ checker-seplzw.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 5
     tiff:PhotometricInterpretation: 2
@@ -130,6 +136,7 @@ checker-clamp.tx     :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "clamp,clamp"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -148,6 +155,7 @@ checker-permir.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "periodic,mirror"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -185,6 +193,7 @@ checker-camera.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -203,6 +212,7 @@ checker-opaque.tx    :  128 x  128, 3 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "2BE3743A64D4309645F94CA7B37D0CD08AF0B38E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -222,6 +232,7 @@ gray-mono.tx         :  256 x  256, 1 channel, uint8 tiff
     oiio:AverageColor: "0.25098"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098"
+    oiio:miplevels: 9
     oiio:SHA-1: "24049CDF337F17E162291C7B626E0588A9D71160"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -241,6 +252,7 @@ pink-mono.tx         :  256 x  256, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25098,0.2,0.14902"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098,0.2,0.14902"
+    oiio:miplevels: 9
     oiio:SHA-1: "41B1A0D1C1EBB4CEEBC7BCEE2CAB2AAAB4139724"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -259,6 +271,7 @@ checker-prman.tx     :  128 x  128, 4 channel, int16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -304,6 +317,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     openexr:roundingmode: 0
 Reading grid.tx
@@ -342,6 +356,7 @@ small.tx             :   64 x   64, 3 channel, uint8 tiff
     oiio:AverageColor: "1,0,0"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "1,0,0"
+    oiio:miplevels: 7
     oiio:SHA-1: "1DD1CB3C76F9A491B115F85A6DAC1B1A8DD2D3CB"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -552,6 +567,7 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
diff --git a/testsuite/oiiotool-maketx/ref/out-win.txt b/testsuite/oiiotool-maketx/ref/out-win.txt
index 0b1a50522b..183cfb0bfb 100644
--- a/testsuite/oiiotool-maketx/ref/out-win.txt
+++ b/testsuite/oiiotool-maketx/ref/out-win.txt
@@ -17,6 +17,7 @@ grid.tx              : 1000 x 1000, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "9B24D4CC05313A43973AC384718D81D19183B691"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -40,6 +41,7 @@ grid-resize.tx       : 1024 x 1024, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "2E23E9B4C6E707427A73B5433B23104D4183724E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -58,6 +60,7 @@ checker-uint16.tx    :  128 x  128, 4 channel, uint16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -76,6 +79,7 @@ checker-1chan.tx     :  128 x  128, 1 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "1D0A2254373A69C054C08672041FC7DE3BAE5179"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -94,6 +98,7 @@ checker-16x32tile.tx :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -112,6 +117,7 @@ checker-seplzw.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 5
     tiff:PhotometricInterpretation: 2
@@ -130,6 +136,7 @@ checker-clamp.tx     :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "clamp,clamp"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -148,6 +155,7 @@ checker-permir.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "periodic,mirror"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -185,6 +193,7 @@ checker-camera.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -203,6 +212,7 @@ checker-opaque.tx    :  128 x  128, 3 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "2BE3743A64D4309645F94CA7B37D0CD08AF0B38E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -222,6 +232,7 @@ gray-mono.tx         :  256 x  256, 1 channel, uint8 tiff
     oiio:AverageColor: "0.25098"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098"
+    oiio:miplevels: 9
     oiio:SHA-1: "24049CDF337F17E162291C7B626E0588A9D71160"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -241,6 +252,7 @@ pink-mono.tx         :  256 x  256, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25098,0.2,0.14902"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098,0.2,0.14902"
+    oiio:miplevels: 9
     oiio:SHA-1: "41B1A0D1C1EBB4CEEBC7BCEE2CAB2AAAB4139724"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -259,6 +271,7 @@ checker-prman.tx     :  128 x  128, 4 channel, int16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -307,6 +320,7 @@ bigval.exr           :    2 x    2, 3 channel, half openexr
     wrapmodes: "black,black"
     oiio:AverageColor: "1e+06,1e+06,1e+06"
     oiio:ConstantColor: "1e+06,1e+06,1e+06"
+    oiio:miplevels: 2
     oiio:SHA-1: "E3D97EED7EE68F1885685F312DDD7D8773C29862"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -349,6 +363,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -389,6 +404,7 @@ small.tx             :   64 x   64, 3 channel, uint8 tiff
     oiio:AverageColor: "1,0,0"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "1,0,0"
+    oiio:miplevels: 7
     oiio:SHA-1: "1DD1CB3C76F9A491B115F85A6DAC1B1A8DD2D3CB"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -599,6 +615,7 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
diff --git a/testsuite/oiiotool-maketx/ref/out.txt b/testsuite/oiiotool-maketx/ref/out.txt
index 58f2b3287f..8bb4ceab26 100644
--- a/testsuite/oiiotool-maketx/ref/out.txt
+++ b/testsuite/oiiotool-maketx/ref/out.txt
@@ -17,6 +17,7 @@ grid.tx              : 1000 x 1000, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 10
     oiio:SHA-1: "9B24D4CC05313A43973AC384718D81D19183B691"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -40,6 +41,7 @@ grid-resize.tx       : 1024 x 1024, 4 channel, uint8 tiff
     YResolution: 72
     oiio:AverageColor: "0.608983,0.608434,0.608728,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 11
     oiio:SHA-1: "2E23E9B4C6E707427A73B5433B23104D4183724E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -58,6 +60,7 @@ checker-uint16.tx    :  128 x  128, 4 channel, uint16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -76,6 +79,7 @@ checker-1chan.tx     :  128 x  128, 1 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "1D0A2254373A69C054C08672041FC7DE3BAE5179"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -94,6 +98,7 @@ checker-16x32tile.tx :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -112,6 +117,7 @@ checker-seplzw.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 5
     tiff:PhotometricInterpretation: 2
@@ -130,6 +136,7 @@ checker-clamp.tx     :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "clamp,clamp"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -148,6 +155,7 @@ checker-permir.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "periodic,mirror"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -185,6 +193,7 @@ checker-camera.tx    :  128 x  128, 4 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -203,6 +212,7 @@ checker-opaque.tx    :  128 x  128, 3 channel, uint8 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
     oiio:BitsPerSample: 8
+    oiio:miplevels: 8
     oiio:SHA-1: "2BE3743A64D4309645F94CA7B37D0CD08AF0B38E"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -222,6 +232,7 @@ gray-mono.tx         :  256 x  256, 1 channel, uint8 tiff
     oiio:AverageColor: "0.25098"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098"
+    oiio:miplevels: 9
     oiio:SHA-1: "24049CDF337F17E162291C7B626E0588A9D71160"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 1
@@ -241,6 +252,7 @@ pink-mono.tx         :  256 x  256, 3 channel, uint8 tiff
     oiio:AverageColor: "0.25098,0.2,0.14902"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "0.25098,0.2,0.14902"
+    oiio:miplevels: 9
     oiio:SHA-1: "41B1A0D1C1EBB4CEEBC7BCEE2CAB2AAAB4139724"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -259,6 +271,7 @@ checker-prman.tx     :  128 x  128, 4 channel, int16 tiff
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
     oiio:BitsPerSample: 16
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -307,6 +320,7 @@ bigval.exr           :    2 x    2, 3 channel, half openexr
     wrapmodes: "black,black"
     oiio:AverageColor: "1e+06,1e+06,1e+06"
     oiio:ConstantColor: "1e+06,1e+06,1e+06"
+    oiio:miplevels: 2
     oiio:SHA-1: "E3D97EED7EE68F1885685F312DDD7D8773C29862"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -349,6 +363,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
+    oiio:miplevels: 8
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -389,6 +404,7 @@ small.tx             :   64 x   64, 3 channel, uint8 tiff
     oiio:AverageColor: "1,0,0"
     oiio:BitsPerSample: 8
     oiio:ConstantColor: "1,0,0"
+    oiio:miplevels: 7
     oiio:SHA-1: "1DD1CB3C76F9A491B115F85A6DAC1B1A8DD2D3CB"
     tiff:Compression: 8
     tiff:PhotometricInterpretation: 2
@@ -599,6 +615,7 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
+    oiio:miplevels: 7
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
diff --git a/testsuite/openexr-multires/ref/out.txt b/testsuite/openexr-multires/ref/out.txt
index d4281e241b..ea91d1c3d1 100644
--- a/testsuite/openexr-multires/ref/out.txt
+++ b/testsuite/openexr-multires/ref/out.txt
@@ -15,6 +15,7 @@ Reading ../openexr-images/MultiResolution/Bonita.exr
     thumbnail_nchannels: 4
     thumbnail_width: 100
     wrapmodes: "clamp,clamp"
+    oiio:miplevels: 10
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
     openexr:roundingmode: 0
@@ -34,6 +35,7 @@ Reading ../openexr-images/MultiResolution/ColorCodedLevels.exr
     screenWindowWidth: 1
     textureformat: "Plain Texture"
     wrapmodes: "periodic,periodic"
+    oiio:miplevels: 10
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
     openexr:roundingmode: 0
@@ -53,6 +55,7 @@ Reading ../openexr-images/MultiResolution/KernerEnvCube.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "CubeFace Environment"
+    oiio:miplevels: 11
     oiio:sampleborder: 1
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -71,6 +74,7 @@ Reading ../openexr-images/MultiResolution/KernerEnvLatLong.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "LatLong Environment"
+    oiio:miplevels: 11
     oiio:sampleborder: 1
     oiio:subimages: 1
     oiio:updirection: "y"
@@ -91,6 +95,7 @@ Reading ../openexr-images/MultiResolution/MirrorPattern.exr
     screenWindowWidth: 1
     textureformat: "Plain Texture"
     wrapmodes: "mirror,mirror"
+    oiio:miplevels: 10
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
     openexr:roundingmode: 0
@@ -110,6 +115,7 @@ Reading ../openexr-images/MultiResolution/OrientationCube.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "CubeFace Environment"
+    oiio:miplevels: 12
     oiio:sampleborder: 1
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -128,6 +134,7 @@ Reading ../openexr-images/MultiResolution/OrientationLatLong.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "LatLong Environment"
+    oiio:miplevels: 11
     oiio:sampleborder: 1
     oiio:subimages: 1
     oiio:updirection: "y"
@@ -148,6 +155,7 @@ Reading ../openexr-images/MultiResolution/PeriodicPattern.exr
     screenWindowWidth: 1
     textureformat: "Plain Texture"
     wrapmodes: "periodic,periodic"
+    oiio:miplevels: 10
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
     openexr:roundingmode: 0
@@ -170,6 +178,7 @@ Reading ../openexr-images/MultiResolution/StageEnvCube.exr
     thumbnail_height: 180
     thumbnail_nchannels: 4
     thumbnail_width: 30
+    oiio:miplevels: 11
     oiio:sampleborder: 1
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -191,6 +200,7 @@ Reading ../openexr-images/MultiResolution/StageEnvLatLong.exr
     thumbnail_height: 50
     thumbnail_nchannels: 4
     thumbnail_width: 100
+    oiio:miplevels: 11
     oiio:sampleborder: 1
     oiio:subimages: 1
     oiio:updirection: "y"
@@ -212,6 +222,7 @@ Reading ../openexr-images/MultiResolution/WavyLinesCube.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "CubeFace Environment"
+    oiio:miplevels: 11
     oiio:sampleborder: 1
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
@@ -230,6 +241,7 @@ Reading ../openexr-images/MultiResolution/WavyLinesLatLong.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "LatLong Environment"
+    oiio:miplevels: 11
     oiio:sampleborder: 1
     oiio:subimages: 1
     oiio:updirection: "y"
@@ -325,6 +337,7 @@ Reading ../openexr-images/MultiView/Impact.exr
     wrapmodes: "clamp,clamp"
     XResolution: 100
     YResolution: 100
+    oiio:miplevels: 10
     oiio:subimages: 1
     openexr:lineOrder: "increasingY"
     openexr:roundingmode: 0
diff --git a/testsuite/python-imagebuf/ref/out.txt b/testsuite/python-imagebuf/ref/out.txt
index 00a6ddb77c..da3669fff1 100644
--- a/testsuite/python-imagebuf/ref/out.txt
+++ b/testsuite/python-imagebuf/ref/out.txt
@@ -35,6 +35,7 @@ Constructing from a bare numpy array:
 
  from 0-d array has_error: True
 Testing read of ../common/textures/grid.tx:
+miplevel: 0  /  11
 channels: 4
 name: ../common/textures/grid.tx
 file_format_name: tiff
@@ -74,6 +75,7 @@ Printing the whole spec to be sure:
   planarconfig = "contig"
   compression = "zip"
   PixelAspectRatio = 1.0
+  oiio:miplevels = 11
   oiio:AverageColor = "0.608983,0.608434,0.608728,1"
   oiio:SHA-1 = "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
   oiio:SourceFileFormat = "tiff"
@@ -104,6 +106,7 @@ Resetting to a different MIP level:
   planarconfig = "contig"
   compression = "zip"
   PixelAspectRatio = 1.0
+  oiio:miplevels = 11
   oiio:AverageColor = "0.608983,0.608434,0.608728,1"
   oiio:SHA-1 = "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
   oiio:SourceFileFormat = "tiff"
@@ -254,6 +257,12 @@ Testing error handling for out-of-range subimage, miplevel
   tahoe-tiny.tif subimage 0 mip 0: True 
   tahoe-tiny.tif subimage 0 mip 1: False Could not seek to subimage=0 miplevel=1
 
+Testing the number of miplevels
+  ../common/bayer.png nmiplevels: 1
+  ../common/grid-small.exr nmiplevels: 1
+  ../common/textures/grid.tx nmiplevels: 11
+  ../common/tahoe-tiny.tif nmiplevels: 1
+
 Done.
 Comparing "out.tif" and "ref/out.tif"
 PASS
diff --git a/testsuite/python-imagebuf/src/test_imagebuf.py b/testsuite/python-imagebuf/src/test_imagebuf.py
index 5469227e6d..2aefea47a8 100755
--- a/testsuite/python-imagebuf/src/test_imagebuf.py
+++ b/testsuite/python-imagebuf/src/test_imagebuf.py
@@ -222,6 +222,14 @@ def test_outofrange_subimage_miplevel() :
         print(" ", f, "subimage 0 mip 1:", ok, buf.geterror())
 
 
+# Test for the number of MIP levels.
+def test_nmiplevels():
+    print("\nTesting the number of miplevels")
+    for f in ["../common/bayer.png", "../common/grid-small.exr",
+              "../common/textures/grid.tx", "../common/tahoe-tiny.tif"]:
+        buf = oiio.ImageBuf(f, 0, 0)
+        print(" ", f, "nmiplevels:", buf.nmiplevels)
+
 
 ######################################################################
 # main test starts here
@@ -349,6 +357,7 @@ def test_outofrange_subimage_miplevel() :
     test_copy_metadata ()
     test_repr_png ()
     test_outofrange_subimage_miplevel ()
+    test_nmiplevels()
 
     print ("\nDone.")
 except Exception as detail:
diff --git a/testsuite/python-imageinput/ref/out-alt.txt b/testsuite/python-imageinput/ref/out-alt.txt
index c9b164ae67..864dfab245 100644
--- a/testsuite/python-imageinput/ref/out-alt.txt
+++ b/testsuite/python-imageinput/ref/out-alt.txt
@@ -62,6 +62,7 @@ Opened "grid.tx" as a tiff
   planarconfig = "contig"
   compression = "zip"
   PixelAspectRatio = 1.0
+  oiio:miplevels = 11
   oiio:AverageColor = "0.608983,0.608434,0.608728,1"
   oiio:SHA-1 = "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
 Subimage 0 MIP level 1 :
diff --git a/testsuite/python-imageinput/ref/out-alt2.txt b/testsuite/python-imageinput/ref/out-alt2.txt
index 3440fabee1..40d958a164 100644
--- a/testsuite/python-imageinput/ref/out-alt2.txt
+++ b/testsuite/python-imageinput/ref/out-alt2.txt
@@ -62,6 +62,7 @@ Opened "grid.tx" as a tiff
   planarconfig = "contig"
   compression = "zip"
   PixelAspectRatio = 1.0
+  oiio:miplevels = 11
   oiio:AverageColor = "0.608983,0.608434,0.608728,1"
   oiio:SHA-1 = "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
 Subimage 0 MIP level 1 :
diff --git a/testsuite/python-imageinput/ref/out-py37-jpeg9d.txt b/testsuite/python-imageinput/ref/out-py37-jpeg9d.txt
index 2231776475..bd7a395531 100644
--- a/testsuite/python-imageinput/ref/out-py37-jpeg9d.txt
+++ b/testsuite/python-imageinput/ref/out-py37-jpeg9d.txt
@@ -65,6 +65,7 @@ Opened "grid.tx" as a tiff
   planarconfig = "contig"
   compression = "zip"
   PixelAspectRatio = 1.0
+  oiio:miplevels = 11
   oiio:AverageColor = "0.608983,0.608434,0.608728,1"
   oiio:SHA-1 = "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
 Subimage 0 MIP level 1 :
diff --git a/testsuite/python-imageinput/ref/out-python3-win-2.txt b/testsuite/python-imageinput/ref/out-python3-win-2.txt
index 13ce3fc767..9fa3945089 100644
--- a/testsuite/python-imageinput/ref/out-python3-win-2.txt
+++ b/testsuite/python-imageinput/ref/out-python3-win-2.txt
@@ -62,6 +62,7 @@ Opened "grid.tx" as a tiff
   planarconfig = "contig"
   compression = "zip"
   PixelAspectRatio = 1.0
+  oiio:miplevels = 11
   oiio:AverageColor = "0.608983,0.608434,0.608728,1"
   oiio:SHA-1 = "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
 Subimage 0 MIP level 1 :
diff --git a/testsuite/python-imageinput/ref/out-python3-win.txt b/testsuite/python-imageinput/ref/out-python3-win.txt
index 691369dd18..8f50d97711 100644
--- a/testsuite/python-imageinput/ref/out-python3-win.txt
+++ b/testsuite/python-imageinput/ref/out-python3-win.txt
@@ -65,6 +65,7 @@ Opened "grid.tx" as a tiff
   planarconfig = "contig"
   compression = "zip"
   PixelAspectRatio = 1.0
+  oiio:miplevels = 11
   oiio:AverageColor = "0.608983,0.608434,0.608728,1"
   oiio:SHA-1 = "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
 Subimage 0 MIP level 1 :
diff --git a/testsuite/python-imageinput/ref/out.txt b/testsuite/python-imageinput/ref/out.txt
index 86f75969a6..4f06a688ac 100644
--- a/testsuite/python-imageinput/ref/out.txt
+++ b/testsuite/python-imageinput/ref/out.txt
@@ -65,6 +65,7 @@ Opened "grid.tx" as a tiff
   planarconfig = "contig"
   compression = "zip"
   PixelAspectRatio = 1.0
+  oiio:miplevels = 11
   oiio:AverageColor = "0.608983,0.608434,0.608728,1"
   oiio:SHA-1 = "233A1D3412A54A5F49814AB7BFFD04F56F46D3D7"
 Subimage 0 MIP level 1 :