ExifTool Forum

General => Metadata => Topic started by: blue-j on March 26, 2024, 05:32:11 PM

Title: ICC Profile Name from the iCCP Chunk in PNGs
Post by: blue-j on March 26, 2024, 05:32:11 PM
I can't for the life of me find a PNG with a valid ICC Profile Name from png:profilename  I scoured the source code, the spec, broke out the hex, and it seems like either something well over my head (very possible!) or just a pseudo-tag in iCCP (https://www.w3.org/TR/png/#11iCCP) that no one is bothering to write to.

I did find samples where ExifTool writes a value (https://exiftool.org/forum/index.php?topic=13172.msg71177#msg71177) to that tag, and then it is readable.  But dagnabbit, Photoshop exports are certainly not showing anything.  Every name is extracted as "Profile name" for me, unless ExifTool wrote it.

- J

Title: Re: ICC Profile Name from the iCCP Chunk in PNGs
Post by: Phil Harvey on March 26, 2024, 08:44:04 PM
I don't understand the problem.  The iCCP format is the same as zTXt, and may contain an extra string before the data in the chunk header.  In both your samples this text is "ICC profile".  You expected something more descriptive?

- Phil
Title: Re: ICC Profile Name from the iCCP Chunk in PNGs
Post by: blue-j on March 27, 2024, 01:40:04 AM
I guess I expected a profile name, like profile description in the ICC spec.  "ICC profile" is like naming my son, "Son"!  it does no work whatsoever.  the presence of the iCCP chunk is enough to announce the profile's embedding.  i think people perhaps just don't care to do the extra work to write the ICC profile name there.  it is somewhat redundant...?

QuoteThe profile name may be any convenient name for referring to the profile

pretty loose spec!

All my tests indicate that ExifTool is working correctly and in accord with the PNG spec, and writers are where the problem (as I see it) is produced.

- J