On Mon, Feb 20, 2017 at 11:56 AM, Martí Maria <marti.ma...@littlecms.com>
wrote:
>
> Hi,
> >Thanks, Marti. Is the white point and transfer function not already
> specified in the profile? Pardon my ignorance,
> >not that familiar with colour transforms.
>
>
> No worries, if you use a real profile, yes, it is included in the profile.
> If you use a built-in profile, that is a template to generate profiles, so
> you need parameters.
>
May I ask what you mean by "real profile" ? Thanks for the code below, I
will try it out, but would the original profile contain information on
gamma and white point ?
Thanks,
Aaron
> Try this:
> // A gamma-2.2 gray space
> static
> cmsHPROFILE Create_Gray22(void)
> {
> cmsHPROFILE hProfile;
> cmsToneCurve* Curve = cmsBuildGamma(DbgThread(), 2.2);
> if (Curve == NULL) return NULL;
>
> hProfile = cmsCreateGrayProfileTHR(DbgThread(), cmsD50_xyY(), Curve);
> cmsFreeToneCurve(Curve);
>
> return hProfile;
> }
>
> Regards
>
> Marti
>
>
> On 20/02/2017 17:33, Aaron Boxer wrote:
>
> Thanks, Marti. Is the white point and transfer function not already
> specified in the profile? Pardon my ignorance,
> not that familiar with colour transforms.
>
> On Mon, Feb 20, 2017 at 11:28 AM, Martí Maria <marti.ma...@littlecms.com>
> wrote:
>
>>
>> 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/GrokImageCo
>> mpression/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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