Hi,
I do love little CMS very much - nice, small and quick.
But I do have an issue with a bit of code and I cannot see what I am
doing wrong.
Maybe one of you guys could help me and tell if I do anything obvious
stupid?
The basic idea is that I do have an image with an embedded profile and
an external profile file.
The external profile can differ and may have e.g. 6 channels.
I want to transform the image with the external profile and read the
pixel values of the output channels.
Here is an example code (leaving out only the input image specific
stuff), which is really a modified version of the basic example seen in
the tutorial:
//START
cmsHPROFILE hInProfile, hOutProfile;
cmsHTRANSFORM hTransform;
//Width and height and pixel type are from the input image
int nInputPixelType = TYPE_BGRA_16;
int nWidth = xxx;
int nHeight = xxx;
//Loading the profiles
hInProfile = cmsOpenProfileFromMem(memoryPointer,size);
hOutProfile = cmsOpenProfileFromFile(szProfileFile, "r");
//Extracting information of the output profile
cmsColorSpaceSignature outputColorSpace = cmsGetColorSpace(hOutProfile);
int nNumOutputChannels = cmsChannelsOf(outputColorSpace); //This is 6 in
my example
//This formatter is used in the transformation
int nOutputFormatter = _cmsLCMScolorSpace(outputColorSpace);
int nNumBytes = T_BYTES(nOutputFormatter); //This is 4 in my example
//I change now the formatter to have 1 byte instead as I want to use
that instead of 4 byte precision
if(nNumBytes != 1)
{
//Clear the first 3 bits
nOutputFormatter &= ~7;
//Set it to 1 Bytes
nOutputFormatter |= 1;
//Retrieve the value again (making sure it is one byte)
nNumBytes = T_BYTES(nOutputFormatter);
}
//Create the transformation
hTransform = cmsCreateTransform(hInProfile, nInputPixelType,
hOutProfile, nOutputFormatter,
INTENT_RELATIVE_COLORIMETRIC, 0);
//Closing the profile
cmsCloseProfile(hInProfile);
cmsCloseProfile(hOutProfile);
//Create a buffer to hold the transformed data
int nNewSizeInBytes = nNumOutputChannels * nHeight * nWidth * nNumBytes;
char* szData = new char[nNewSizeInBytes];
memset(szData,0,nNewSizeInBytes);
//Transform the data
int nRowLengthInBytes = nNumOutputChannels*nNumBytes*nWidth;
for(int i = 0; i < nHeight; ++i)
{
char* pixelBuffer = READ_BUFFER_FROM_IMAGE_FOR_ROW(i);
cmsDoTransform(hTransform, pixelBuffer,szData + i
*nRowLengthInBytes, nWidth);
}
//END
The issue is that the transformation does work - I do get the data for
each channel. But the transformed image data is only 1/3 wide (the
height does match) - the other 2/3 of the image are untouched (e.g. when
I initialize szData with white instead of black, it remains white).
I must be doing something really stupid - but I cannot see what is wrong?
Any help or pointers are highly appriciated.
It would help me to know if the litte CMS code is ok but I have an issue
either in the input buffer or the output buffer?
Thank you very much in advance
Michael
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