feat: CICP metadata support for PNG

src/doc/oiiotool.rst

@@ -4676,6 +4676,15 @@ will be printed with the command `oiiotool --colorconfiginfo`.
 
     This was added to OpenImageIO 2.5.
 
+.. option:: --cicp <pri>,<trc>,<mtx>,<vfr>
+
+    The `--cicp` command adds, modifies, or removes a `"CICP"` attribute 
+    belonging to the top image, stored as an array of four integers.  
+    The integers represent, in order, the color primaries, transfer 
+    function, color matrix (for YUV colorspaces), and 
+    video-full-range-flag.
+
+    This was added to OpenImageIO 3.1.
 
 |
 

src/doc/stdmetadata.rst

@@ -164,6 +164,17 @@ Color information
     window that are not overlapping the pixel data window.  If not supplied,
     the default is black (0 in all channels).
 
+.. option:: "CICP" : int8[4]
+
+    The CICP color space information, as defined by
+    `ITU-T H.273 <https://www.itu.int/rec/T-REC-H.273>`_.  This is an array
+    of four 8-bit integers, with the following meanings:
+
+    - `[0]` : color primaries
+    - `[1]` : transfer characteristics
+    - `[2]` : matrix coefficients
+    - `[3]` : full range flag
+
 .. option:: "ICCProfile" : uint8[]
             "ICCProfile:...various..." : ...various types...
 

src/include/OpenImageIO/imageio.h

@@ -1087,6 +1087,9 @@ class OIIO_API ImageInput {
     /// - `"exif"` :
     ///       Can this format store Exif camera data?
     ///
+    /// - `"cicp"` :
+    ///       Does this format support embedding CICP metadata?
+    ///
     /// - `"ioproxy"` :
     ///       Does this format reader support reading from an `IOProxy`?
     ///