[Converter] Support OpenImageIO

[jo-chemla]

OpenImageIO supported formats through plugins, via command iconvert and additional edition via oiiotool.

Aimed at image conversion - so already done via Vips and GraphicsMagick, but some missing formats might be useful to add - see below, eg raw camera files like DNG, CR2, NEF, ARW which might be missing from vips.

Supports BMP, Cineon, DDS, DICOM, DPX, FITS, GIF, HDR/RGBE, HEIF/HEIC/AVIF, ICO, IFF, JPEG, JPEG-2000, Null format, OpenEXR, OpenVDB, PNG, PNM / Netpbm, PSD, Ptex, RAW digital camera files, RLA, SGI, Softimage PIC, Targa, Term (Terminal), TIFF, Webp, Zfile

[Aymendje]

Which formats are missing from GraphicsMagick ?
http://www.graphicsmagick.org/GraphicsMagick.html

[jo-chemla]

Indeed GraphicsMagick supports all raw camera files I've searched for. I could not find references to these ones searching in the supported formats files:

• OpenEXR (supported by vips), OpenVDB (usually for storing 3d volumetric data),
• HEIF/HEIC/AVIF and Webp which are both formats and compression types used in other files like tiffs
• more formats I do not know like DDS, DICOM, DPX,HDR/RGBE, IFF, Ptex, Softimage PIC, Zfile.
• all the other are already supported by GraphicsMagick. I just added OpenImageIO because it is also a well known alternative like Vips and GraphicsMagick, and might be interesting for some use-cases