EXIF ColorSpace (0xA001) is a 16-bit integer in the ExifIFD with two standard values: 1 for sRGB and 0xFFFF (65535) for Uncalibrated. Uncalibrated does not name a color space. It only says the image is not sRGB. Color-managed software ignores the tag and reads the embedded ICC profile, which describes the colors precisely.
ExifTool knows a few more values, all non-standard:
| Raw value | ExifTool prints | Status |
|---|---|---|
| 1 | sRGB | Standard |
| 2 | Adobe RGB | Non-standard |
| 0xFFFD | Wide Gamut RGB | Some Sony cameras |
| 0xFFFE | ICC Profile | Some Sony cameras |
| 0xFFFF | Uncalibrated | Standard |
How Adobe RGB is actually signaled
A camera set to Adobe RGB writes Uncalibrated and sets the Interoperability Index to R03. That pair is the DCF convention for an Adobe RGB "option file". Canon and Nikon also mark those files with a leading underscore in the name (_MG_0001.JPG, _DSC0001.JPG).
$ exiftool -G1 -s -ColorSpace -InteropIndex adobe.jpg
[ExifIFD] ColorSpace : Uncalibrated
[InteropIFD] InteropIndex : R03 - DCF option file (Adobe RGB)With -n the two read 65535 and R03.
Phones and the Uncalibrated surprise
iPhone HEIC photos say Uncalibrated and embed a Display P3 profile, so the tag tells you only that the file is wider than sRGB. If you see Uncalibrated on a web image, the profile is the thing to check.
ExifTool can produce the same label on files that are plain sRGB. When version 12.76 has to create an ExifIFD from scratch, for instance to write ExposureTime into a file with no EXIF, it adds ColorSpace = Uncalibrated as a mandatory default, along with ExifVersion 0232 and FlashpixVersion 0100. A one-tag edit can therefore leave an sRGB image claiming otherwise. Fix it with exiftool -ColorSpace=sRGB photo.jpg.
You can view ColorSpace in the EXIF reader and change it in the editor for JPEG and TIFF. Changing it converts nothing: it is a label, and if it disagrees with the ICC profile, color-managed apps follow the profile. The EXIF data guide shows where the ExifIFD sits in the file.