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

[Martí M. <mar...@li...>]

Hi,

You need to specify white point and transfer function to 
cmsCreateGrayProfile(), see manual page 28

Regards

Marti

On 20/02/2017 7:04, Aaron Boxer wrote:
> Hello,
>
> I have a jpeg 2000 file with an ICC profile.
>
> PCS is cmsSigXYZData and color space is cmsSigGrayData.
>
> The file can be found here: 
> https://github.com/GrokImageCompression/grok/issues/38
>
> I am working on a library that decodes the jpeg 2000 file and applies 
> the ICC profile, using LCMS.
>
> Currently, I have this code:
>
>  in_type = TYPE_GRAY_8;
>  out_type = TYPE_RGB_8;
>  out_prof = cmsCreate_sRGBProfile();
>
> and I can create the transform and apply the ICC profile, but the 
> output is an RGB file.
> What I would like is to output a grayscale file.
>
> So, if I instead call
>
> out_prof = cmsCreateGrayProfile(NULL,NULL);
>
> then cmsCreateTransform  returns NULL and I can't apply the profile.
>
>
> What is the best way of creating a transform for this kind of 
> grayscale image ?
>
> Thanks so much,
> Aaron
>
>
>
>
>
>
>
>
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