ImageIO

ImageIO is Apple's Framework that handles image parsing through its public API.

SUPPORTED IMAGE FORMATS

The supported image formats can be enumerated by reverse engineering the ImageIO library, Some formats are only supported by macOS, while others are supported by both macOS and iOS.
There is also support for RAW images

Format Name	Is Supported by iOS	Is Supported by macOS
AI	✅	✅
ASTC	✅	✅
ATX	✅	✅
AppleJPEG	✅	✅
BC	✅	✅
BMP	✅	✅
CUR	✅	✅
ETC	✅	✅
GIF	✅	✅
HEIF	✅	✅
ICNS	✅	✅
ICO	✅	✅
JP2	✅	✅
KTX	✅	✅
KTX2	✅	✅
LibJPEG	✅	✅
MPO	✅	✅
OpenEXR	✅	✅
PBM	✅	✅
PDF	✅	✅
PNG	✅	✅
PICT	❌	✅
PSD	✅	✅
PVR	✅	✅
RAD	✅	✅
SGI	❌	✅
TGA	✅	✅
TIFF	✅	✅
WebP	✅	✅
Total Supported Formats:	27	29

This summary was taken based on iOS 16.4 and macOS 13.3, supported formats may change in the future.

References

• Fuzzing ImageIO by Samuel Groß, Project Zero