Re: [Lcms-user] Apply profile with PCS = cmsSigXYZData, Color Space = cmsSigGrayData

[Noel C. <NCa...@Pr...>]

> For other formats, such as PNG, I would need to transform.

 

I believe a PNG file can carry a color profile tag, but there are certainly formats that can't.

 

Not to belabor this, but does your design specify what color space the data will be in if it saved in an image file format that does not carry a profile tag?

 

There is no standard for what color space untagged images should be stored in.  Because of the mix of computers in the world and the things that have been done in the past, you might meet expectations more of the time if you were save color images in the sRGB IEC61966-2.1 color space.  Windows has been described as embracing "sRGB by default", for example.  But that's up to you.

 

If you are anticipating prompting the user for target color space information, then that could resolve the problem.

 

-Noel

 

From: Aaron Boxer [mailto:bo...@gm...] 
Sent: Mon, February 20, 2017 12:02 PM
To: Noel Carboni
Cc: lcm...@li...
Subject: Re: [Lcms-user] Apply profile with PCS = cmsSigXYZData, Color Space = cmsSigGrayData

 

Thanks, Noel. That is a good point. For TIFF, I can store the profile in the TIFF file, and avoid transforming.

For other formats, such as PNG, I would need to transform.

 

On Mon, Feb 20, 2017 at 11:49 AM, Noel Carboni <NCa...@pr...> wrote:

> Thanks, Noel. This is not for display on monitor. JPEG 2000 supports embedded ICC profiles, and I am 

> trying to use the profile when decoding the image.

 

I guess I'm still not clear:  Why are you transforming the data into another color space?

 

If you're trying to decode it then save it as another kind of file (e.g., .tiff or .jpg or something that can carry its own color profile tag), maybe you should consider just maintaining the color profile it's already got.

 

What I'm saying is that maybe you just want to decode the data, then save the data in another file, and tag that file with the same profile the JPEG2000 file started with, making no color transformation on the decoded data at all.  LittleCMS need not be involved with that.

 

As Marti mentioned, if you DO want to transform the color values into a different color space, you need to specify what that color space is.

 

-Noel