On 08/01/2009 01:05 PM, photocomix wrote:

i never noticed a similar bug, even if i used Gimp to save as copy thousands of jpeg, and i would never believed this possible, but i have to face evidence

to the point image dimensions: 90x116 Size: 547KB

And what is really weird is that seems impossible , re-saving from gimp as jpg reduce the file size...even at quality 1 ( !!) i can't shrink it

The JPEG has an embedded ICC color profile which GIMP ignores since it's a CMYK profile, but it keeps it around anyway and writes it to the JPEG if you resave it.

To see the size of the attached color profile, first extract it:

$ exiftool -icc_profile -b -w icc lightbulb.jpg

Then look at how big it (and the image) is:

$ du -hb lightbulb.*

which gives the output

557168 lightbulb.icc 560484 lightbulb.jpg

/ Martin

On 08/01/2009 08:37 AM, Martin Nordholts wrote:

On 08/01/2009 01:05 PM, photocomix wrote:

i never noticed a similar bug, even if i used Gimp to save as copy thousands of jpeg, and i would never believed this possible, but i have to face evidence

to the point image dimensions: 90x116 Size: 547KB

And what is really weird is that seems impossible , re-saving from gimp as jpg reduce the file size...even at quality 1 ( !!) i can't shrink it

The JPEG has an embedded ICC color profile which GIMP ignores since it's a CMYK profile, but it keeps it around anyway and writes it to the JPEG if you resave it.

To see the size of the attached color profile, first extract it:

$ exiftool -icc_profile -b -w icc lightbulb.jpg

Then look at how big it (and the image) is:

$ du -hb lightbulb.*

which gives the output

557168 lightbulb.icc 560484 lightbulb.jpg

/ Martin

Martin,

Very "enlightening".

In normal use of the program, how would the user known that there was such an embedded ICC color profile and thus to use the technique you outlined? Or is this just one of those "you have to know" kind of situations?

Jay

On Sun, Aug 2, 2009 at 12:23 AM, Jay Smith wrote:

On 08/01/2009 08:37 AM, Martin Nordholts wrote:

On 08/01/2009 01:05 PM, photocomix wrote:

i never noticed a similar bug, even if i used Gimp to save as copy

thousands

of jpeg, and i would never believed this possible, but i have to face evidence

to the point image dimensions: 90x116 Size: 547KB

And what is really weird is that seems impossible , re-saving from gimp

as

jpg reduce the file size...even at quality 1 ( !!) i can't shrink it

The JPEG has an embedded ICC color profile which GIMP ignores since it's a CMYK profile, but it keeps it around anyway and writes it to the JPEG if you resave it.

To see the size of the attached color profile, first extract it:

$ exiftool -icc_profile -b -w icc lightbulb.jpg

Then look at how big it (and the image) is:

$ du -hb lightbulb.*

which gives the output

557168 lightbulb.icc 560484 lightbulb.jpg

/ Martin

Martin,

Very "enlightening".

In normal use of the program, how would the user known that there was such an embedded ICC color profile and thus to use the technique you outlined?

Alt+Enter (Image Properties) shows whether there is an ICC profile attached (and what it describes itself as).
Perhaps it should also mention the size of the profile

David

On 08/01/2009 09:11 PM, photocomix wrote:

@ David
Perhaps it should also mention the size of the profile will be nice,as will be useful a option a option to discard it.(as Exif data that occupy much less space may be discarded)..i mean a option from the "Save" (or if you prefer the term "Export")dialog

Or similar issues are too rare to require changes ?

To me, keeping the CMYK profile around and writing it to an RGB jpeg does not make sense; I don't think GIMP does the right thing here. Showing the size of the color profile would be informative, but only a workaround to the problem we're seeing here.

I don't want to spend time to patch things here and there with regards to color management though. We need a specification on how color profiles should be managed on a bigger scale, otherwise we'll end up with an inconsistent program.

/ Martin

On Sat, 1 Aug 2009 21:11:51 +0200 (CEST) "photocomix" wrote:

To see the size of the attached color profile, first extract it:

$ exiftool -icc_profile -b -w icc lightbulb.jpg

Then look at how big it (and the image) is:

$ du -hb lightbulb.*

which gives the output

557168 lightbulb.icc 560484 lightbulb.jpg

/ Martin

Alt+Enter (Image Properties) shows whether there is an ICC profile attached (and what it describes itself as). Perhaps it should also mention the size of the profile

David

@Martin

Thank a lot to solve the mistery

@ David

Perhaps it should also mention the size of the profile

will be nice,as will be useful a option a option to discard it.(as Exif data that occupy much less space may be discarded)..i mean a option from the "Save" (or if you prefer the term "Export")dialog

Or similar issues are too rare to require changes ?

You probably already know, but if you Copy and Paste as New Image, you will get rid of the icc stuff

owen@owen-desktop:~/images$ du -hb lightbulb* 3103 lightbulb1.jpg
560484 lightbulb.jpg

Owen

From: Martin Nordholts

To me, keeping the CMYK profile around and writing it to an RGB jpeg does not make sense;

In similar cases make even less sense. The original was cropped so that was a tiny snippet of a large tif. why a almost microscopic crop should conserve more then 500kb of ICC profile belonging to a large original?

Anyway the export dialog already have a option to discard exif data, even if the file size of exif is not relevant,

a option to discard not only exif but also ICC, will avoid to inflate the file size with gigantic but unusable data

PhotoComix