Re: [Lcms-user] lcms demo program src?

[<ma...@li...>]

Hi,

Well, of course you need to handle both senses :-)
Here is the patch for the encoder.

Regards,
Marti.


----- Original Message -----
From: "John Gray" <gr...@ag...>
To: "Martí Maria" <ma...@li...>
Cc: <lcm...@li...>
Sent: Saturday, June 30, 2001 3:13 PM
Subject: Re: [Lcms-user] lcms demo program src?


Marti,

Your patch works well for reading in the botched adobe images, but it
also causes a problem.  When I asked the ijg lib to write out a CMYK
jpeg, it writes out the adobe markers, but writes out the componets
correctly.  Now when I read in image I created, it assumes that adobe
created, and inverts the componets.

See a work around for this?

Thanks,

John

Martí Maria wrote:

> John,
>
> Most CMYK JPEG comes inverted. This is a long history about a Junior
> programmer that did a mistake in early versions of PhotoShop, and adobe
> trying to keep backwards compatibilty. All CMYK JPEG from adobe
> programs  are stored with CMYK inks inverted.
>
> In a conversation with Tom Lane, time ago, he told me that he cannot
> change this behaviour on ijg code, since this will break existing
> applications that are aware of this, and does the inversion by itselves.
>
> I am using a patched version of  ijg, that does return correct inks, on
> depending of adobe markers. I attach the code as well, (is very small).
>
> If you don't like to use modified version of a library, you can provide
> your own reversing. Is only a matter of detect if adobe marker is present,
> and if so, reverse (255-x) the channels.
>
> About the demo sources, well, the demo is using a image processing
> library still in development and a lot more complex that the CMM itself,
> so I'm afraid it would be of little use.  The cmyk->srgb is only a matter
> of opening cmyk profile on input and srgb on output, and then apply
> transform. Anyway, if you experience any problem  feel free to drop
> me a note.
>
> Regards,
> Marti.
>



--
John Gray                           gr...@ag...
AgoraNet, Inc.                      (302) 224-2475
102 E. Main Street, Suite 303       (302) 224-2552 (fax)
Newark, De 19711                    http://www.agora-net.com


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