AROT Missing

[Neal Krawetz]

Sometime between 13.04 and 13.27, the AROT output vanished.

I had been using AROT and "Records" to detect tampering.

It looks like some of the AROT-related fields are being decoded under XMP, but AROT really is a different beast compared to XMP (or even makernotes). It really should be it's own metadata section.

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ExifTool Version Number         : 13.03
Warning                         : [minor] Unknown APP10 'AROT' segment (N=188)
Compared to 13.27, which doesn't give the warning.

The N is the number of rows (N=188).
This means there should be (N+1)*16 = 3024 rows to the picture.
If the EXIF ImageHeight is not 3024, then the image has been altered. (It could be as simple as a rotation, but it could be something else.) This example comes from an image that is 4032x3024, so the N matches.

(A match does not mean it is unaltered, but a miss means it was post-processed or altered.)

[Phil Harvey]

Ah, here is the reason:

Dec. 4, 2024 - Version 13.05
  - Decode APP10 AROT HDRGainCurve and APP2 URN UniformResourceName

- Phil

[StarGeek]

Maybe version 13.05?

Decode APP10 AROT HDRGainCurve and APP2 URN UniformResourceName

So the tag you would be looking for would be the HDRGainCurve. Though the output probably isn't as simple as N=### anymore.

[Neal Krawetz]

For my own uses, I was turning the AROT warning into a separate header for the AROT field. The new "HDR Gain Curve" doesn't help since it doesn't tell the number of lines (N).

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< ===== AROT =====
< Records             : 165
78a75,76
> ===== JPEG =====
> HDR Gain Curve      : (Binary data 1126 bytes)
Any chance you could extract this separately?
E.g., instead of:

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---- JPEG ----
HDR Gain Curve                  : (Binary data 1126 bytes, use -b option to extract)Use:

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---- AROT ----
HDR Gain Curve Count:  188
HDR Gain Curve                  : (Binary data 1126 bytes, use -b option to extract)HDR Gain Curve Count, HDR Gain Curve Rows, AROT Rows, whatever. But that number is really important to me.

[Phil Harvey]

ExifTool 13.28 will decode this as HDRGainCurveSize, and I'll put this in a new AROT group as you suggest.

- Phil

[Neal Krawetz]

Wonderful! Thank you!