Read CMYK tags from tiff image using libtiff

Question

I need to read C M Y and K bits from .tiff image using libtiff. I have set this so far:

TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, 4);

TIFFSetField(tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_SEPARATE);
TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_SEPARATED);
TIFFSetField(tif, TIFFTAG_INKSET, INKSET_CMYK);
TIFFSetField(tif, TIFFTAG_NUMBEROFINKS, 4);
TIFFGetField(tif, TIFFTAG_IMAGEWIDTH, &w);
TIFFGetField(tif, TIFFTAG_IMAGELENGTH, &h);
TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, 8,8,8,8);
TIFFSetField(tif, TIFFTAG_ROWSPERSTRIP, h);

npixels=h*w;

raster = (uint32*) _TIFFmalloc(npixels * sizeof (uint32));

if(raster != NULL) {
    ImageStatePtr ptr1 = ImageStatePtr(new ImageState(QFileInfo(filename).fileName());
    Format f;
    f.setColorModel(Format::CMYK);
    f.setColorDepth(32);
    ptr1->setFormat(f);
    while(tif)
    { 
        int C...;//get C pixels
        int M...;//get M pixels
        int Y...;//get Y pixels
        int K...;//get K pixels
    }

I hope for a quick answer. TY