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Bug 436198 - improve handling of iCCP chunk in PNG plug-in
improve handling of iCCP chunk in PNG plug-in
Status: RESOLVED FIXED
Product: GIMP
Classification: Other
Component: Plugins
git master
Other All
: Normal enhancement
: ---
Assigned To: GIMP Bugs
GIMP Bugs
Depends on:
Blocks:
 
 
Reported: 2007-05-05 20:52 UTC by Sven Neumann
Modified: 2007-08-07 14:20 UTC
See Also:
GNOME target: ---
GNOME version: ---


Description Sven Neumann 2007-05-05 20:52:11 UTC 
The PNG spec says:

A PNG encoder that writes the iCCP chunk is encouraged to also write gAMA and
cHRM chunks that approximate the ICC profile, to provide compatibility with
applications that do not use the iCCP chunk. When the iCCP chunk is present, PNG
decoders that recognize it and are capable of colour management [ICC] shall
ignore the gAMA and cHRM chunks and use the iCCP chunk instead and interpret it
according to [ICC-1] and [ICC-1A]. PNG decoders that are used in an environment
that is incapable of full-fledged colour management should use the gAMA and cHRM
chunks if present.

A PNG datastream should contain at most one embedded profile, whether specified
explicitly with an iCCP chunk or implicitly with an sRGB chunk.
Comment 1 Sven Neumann 2007-08-07 14:20:30 UTC 
2007-08-07  Sven Neumann  <sven@gimp.org>

	* plug-ins/common/png.c (save_image): in the absence of an
	embedded color profile, write the sRGB chunk.

I think this is good enough. We never had complaints about our PNG files and even though the spec suggests that we also write gAMA and cHRM chunks, most people will prefer a smaller PNG file than one that works slightly better with some obscure applications that interpret these chunks but ignore the sRGB and iCCP chunks.