In the JPEGImagePlugin.py module, there's a hack to handle Photoshop 2.5 
CMYK JPEG images (around line 273)... that's causing half the problem upon 
loading JPEG's.  By commenting that out, you get a proper image, although 
it's still inverted.

I can't seem to find the right place to re-invert the image upon load, but 
I'll see what I can find.  Anyone with suggestions would be welcome. 
There's probably a better way to do this though, so the data is read 
correctly in the first place (in CMYK, 0,0,0,0 = white, 255,255,255,255 = 
full black... this is probably the problem).

Kevin.
----- Original Message ----- 
From: <kevin@[...].com> 
To: "Cesare Leonardi" <ced@[...].com> ; <image-sig@[...].org>
Sent: Saturday, April 15, 2006 1:32 PM
Subject: Re: [Image-SIG] Problem with JPEG and CMYK color space


>  Actually, the problem is that PIL also has problems reading CMYK JPEG 
>  files
>  apparently.  I just proved that by loading your CMYK test files and doing 
>  a
>  "show", then loading a CMYK TIFF file and doing a show (note that to use
>  show, it converts to RGB with the internal conversion, so the colors won't
>  be perfect).  The TIFF loaded fine, the JPEG didn't.
> 
>  The patch I've submitted fixes the problem with saving incorrectly, but
>  doesn't fix the reading issue (yet).  So, as long as your source CMYK 
>  image
>  doesn't come from a JPEG file it's ok (with my invert patch).
> 
>  I'll see if I can spend some time looking at that this weekend.
> 
>  Kevin.
>  ----- Original Message ----- 
>  From: "Cesare Leonardi" <ced@[...].com>
>  To: <image-sig@[...].org>
>  Sent: Friday, April 14, 2006 9:38 AM
>  Subject: Re: [Image-SIG] Problem with JPEG and CMYK color space
> 
> 
> > kevin@[...].com ha scritto:
> >> When saving a CMYK file to JPG, PIL seems to invert the colors.  I've
> >> submitted a patch to Fredrik already for this, and it should be in the
> >> next major build.
> >>
> >> Adding a simple invert to the image before saving will help.
> >
> > Thanks all for your responses.
> >
> > Kevin, i've made some tests following what you've suggested and here is
> > the results.
> > To obtain the color inversion i've used the function invert() in
> > ImageChops module. I've added the code and the new sample images in this
> > page (see "part 2"):
> > http://www.bernispa.com/pil/index.html
> >
> > As you can see your suggestion works partially.
> > Images 02 and 03 (that was particular in "part 1") are the only that
> > after the inversion looks ok.
> > All the other images looks less dark, but the color are always different
> > than the original.
> > The particular thing to note is that the images produced by the
> > inversion looks the same as Image.show(). Seems that show() already do
> > the inversion.
> >
> > There is another thing that i have noted only now: the images saved by
> > PIL are often less big than the original. Sometimes much less. For
> > example:
> > test01: 1435 KB   test01-dst: 198 KB   test01-dst-invert: 198 KB
> > test04: 1237 KB   test01-dst: 405 KB   test01-dst-invert: 405 KB
> > test08: 1647 KB   test01-dst: 777 KB   test01-dst-invert: 776 KB
> > test09: 1715 KB   test01-dst: 665 KB   test01-dst-invert: 665 KB
> > test10: 2032 KB   test01-dst: 659 KB   test01-dst-invert: 659 KB
> > I can think that PIL optimize the compression, but that difference are
> > really big. Isn't it suspicious? I expect that saving an image in a new
> > file without modifications produces a file very similar to the original,
> > isn't it?
> > The original images was not produced by me so the author can have used
> > low compression. I cannot make tests since i haven't a program that can
> > save in CMYK (Gimp seems not able).
> >
> > Regards.
> >
> > Cesare.
> > _______________________________________________
> > Image-SIG maillist  -  Image-SIG@[...].org
> > http://mail.python.org/mailman/listinfo/image-sig
> >
> >
> >
> 
> 
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>  http://mail.python.org/mailman/listinfo/image-sig
> 
> 
>  


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