fix(ImageBuf): IB::nmiplevels() returns 0 for non-IC ImageBuf

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;
 }
 

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

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

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

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;
 }

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.

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 })) {

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;

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

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

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