Hello,
Thanks for your code, it works. I'm still having problems with
selecting the right cmsCIExyYTRIPLE settings (given it's to convert
from Mac-created sRGB/AdobeRGB to linear for further rendering and
compositing), but overall - code compiles, works and even produces the
images.
So - thanks again.
Alexei
On 3/12/07, Kai-Uwe Behrmann <[EMAIL PROTECTED]> wrote:
> Alexei,
>
> below a example how the linear RGB profile.
> You can of course take some other standard values.
>
> void
> write_profile(float gamma, float rx, float ry, float gx, float gy,
> float bx, float by) {
> cmsCIExyYTRIPLE p = {{rx,ry},{gx,gy},{bx,by}};
> LPGAMMATABLE g[3];
> g[0] = g[1] = g[2] = cmsBuildGamma(1, gamma);
> cmsHPROFILE hp = cmsCreateRGBProfile( cmsD50_xyY(), &p, g);
> _cmsSaveProfile( hp, "matrixRGB.icc" );
> cmsCloseProfile(hp);
> }
>
> regards
> Kai-Uwe Behrmann
> --
> development for color management
> www.behrmann.name + www.oyranos.org + www.cinepaint.org
>
>
> Am 12.03.07, 16:19 -0700 schrieb Alexei Puzikov:
>
> > Hello,
> >
> > I've tried to find out the answer to this question in tutorial,
> > samples sources and in the mailing list, but failed to achieve the
> > required results.
> >
> > So, I have lots of TIFF files created on Macs with Adobe Photoshop.
> > Some of them are in sRGB; most of them are in AdobeRGB. All of them
> > have the corresponding ICC profiles embedded inside.
> >
> > So, I need to convert them to linear color space, basically, by going
> > >from sRGB (approx. gamma 2.2, but the exact algorithm is slightly
> > different) and AdobeRGB (also almost 2.2). Previously I've been
> > working with sRGB only and used some custom math, but now we're
> > switching to AdobeRGB and I don't want to touch the math anymore, so I
> > want to switch to LCMS for conversion.
> >
> > The problem is - how do I create the linear gamma 1.0 profile and
> > corresponding transform?
> >
> > LPGAMMATABLE Transfer[3];
> > cmsHPROFILE LinearProfile;
> >
> > Transfer[0] = cmsBuildGamma(256, 1);
> > Transfer[1] = cmsBuildGamma(256, 1);
> > Transfer[2] = cmsBuildGamma(256, 1);
> >
> > LinearProfile = cmsCreateLinearizationDeviceLink(icSigRgbData,
> > Transfer);
> >
> > doesn't work:
> >
> > int iccfound = 0;
> > iccfound = TIFFGetField(in, TIFFTAG_ICCPROFILE, &profile_size,
> > &icc_profile);
> > if (iccfound) {
> > TiffProfile = cmsOpenProfileFromMem(icc_profile,
> > profile_size);
> > }
> >
> > and then
> >
> > DWORD PixelType = TYPE_RGBA_16;
> > hTransform = cmsCreateTransform(TiffProfile,
> > PixelType,
> > LinearProfile,
> > PixelType,
> > INTENT_PERCEPTUAL, 0);
> >
> > results in error 12288: invalid PCS. And I still think it shouldn't,
> > since it's not real profile per se.
> >
> > So what's the basic idea? How can I create the linear profile without
> > reverting to some ICC files I have no idea where to get from?
> >
> > Sorry if the question is dumb, but I'm really out of ideas.
> >
> > Alexei Puzikov
> >
>
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