Thanks a lot for help! When I convert with Photoshop to sRGB / Absolute Colorimetric, I get different colors than I get from lcms. Example: At xy(268, 190) I get RGB(0,163,77) in Photoshop, but RGB(77, 164, 1) in lcms. Both images are opened in Photoshop for picking the colors.
I noticed the color shifts in the border areas, too, but the difference is much
bigger there than the difference generated by different positions on the screen.
Code is pretty simple:
QImage* image = new QImage("/Users/ar/Desktop/basICColor_CM-Ampel.jpeg");
cmsHPROFILE hInProfile, hOutProfile;
cmsHTRANSFORM hTransform;
hInProfile = cmsOpenProfileFromFile("/Users/ar/Desktop/ampel.icc", "r");
hOutProfile =
cmsOpenProfileFromFile("/System/Library/ColorSync/Profiles/sRGB Profile.icc",
"r");
hTransform = cmsCreateTransform(hInProfile,
TYPE_BGR_8,
hOutProfile,
TYPE_BGR_8,
INTENT_ABSOLUTE_COLORIMETRIC, 0);
cmsCloseProfile(hInProfile);
cmsCloseProfile(hOutProfile);
uchar *rgbOutTemp = new uchar[(image->width() * image->height()) * 3];
uchar *rgbInTemp = new uchar[(image->width() * image->height()) * 3];
int j = 0;
for(int y = 0; y < image->height(); y++){
for(int x = 0; x < image->width(); x++){
QColor col = image->pixel(x, y);
rgbInTemp[j] = col.blue();
rgbInTemp[j + 1] = col.green();
rgbInTemp[j + 2] = col.red();
j += 3;
}
}
cmsDoTransform(hTransform,rgbInTemp,rgbOutTemp,image->width()*image->height());
QImage* imout = new QImage(image->width(), image->height(),
QImage::Format_RGB32);
int s = 0;
for(int h = 0; h < imout->height(); h++){
for(int w = 0; w < imout->width(); w++){
QColor color(rgbOutTemp[s], rgbOutTemp[s+1], rgbOutTemp[s+2]);
imout->setPixel(w, h, color.rgb());
s+=3;
}
}
ui->label->setPixmap(QPixmap::fromImage(*imout));
imout->save("/Users/ar/Desktop/saved.jpg","JPG",100);
Regards
Andreas
Am 27.09.2012 um 20:31 schrieb Marti Maria <marti.ma...@littlecms.com>:
>
> Hi Andreas,
>
> I have tested your image with PS CS4 and get 1 digital count of deviation of
> PhotoShop, which is due to the way different CMM do rounding. I can see no
> differences in color.
>
> Could you please detail the steps you follow to get different results?
>
> Thanks
> Marti.
>
>
> El 27/09/2012 19:37, Andreas Rettig escribió:
>> Hello,
>>
>> I'm trying to make my first steps with LCMS and build a very simple
>> application to get familiar with everything.
>> All I want to do is transform a RGB-Jpeg from a special input profile to
>> sRGB and produce the same results I get when I do exactly the same in
>> Photoshop.
>>
>> I'm using that image for testing with its embedded ICC profile as Input
>> profile:
>>
>> http://www.colormanagement.org/download_files/basICColor_CM-Ampel.jpg
>>
>> Then I do a simple transformation from ampel.icc -> sRGB.icc, with different
>> intents.
>> The results are always a little different from what I can produce in
>> Photoshop (using the same profiles and the same intent).
>>
>> The traffic light is green after the transformation, which shows me that it
>> roughly works - but I expect to get exactly the same result.
>>
>> The same happens in Gimp - it's always a little different from what I get
>> through lcms (I saved the results to a file and checked RGB-Values).
>> Especially these grids at the borders have very different colors.
>>
>> Sourcecode is more or less from the examples, nothing special. Profiles are
>> the exactly the same in lcms and Photoshop.
>>
>> Regards
>> Andreas
>>
>>
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