2008.04.23 13:58 "[Tiff] transparent tiff", by Roman Kazmin

Hi everybody. I'm trying to create transparent tiff file. But I receive
usual tiff file. Where is my mistake? I'm trying to make following - red
screen with transparent green rectange at the center. Below is my code:

int main(int argc, char **argv)
{
         TIFF *tif;

         char    buffer[4*1024];
         int     width = 1024, height = 768, row;

         uint32 temp = EXTRASAMPLE_ASSOCALPHA;
         tif = TIFFOpen("3d.tif", "w");

TIFFSetField (tif, TIFFTAG_IMAGEWIDTH, width);

         TIFFSetField (tif, TIFFTAG_IMAGELENGTH, height);
         TIFFSetField (tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
         TIFFSetField (tif, TIFFTAG_SAMPLESPERPIXEL,  4);
         TIFFSetField (tif, TIFFTAG_BITSPERSAMPLE,    8);
         TIFFSetField (tif, TIFFTAG_EXTRASAMPLES,     1, &temp);

TIFFSetField (tif, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT);

         TIFFSetField (tif, TIFFTAG_PHOTOMETRIC,      PHOTOMETRIC_RGB);

TIFFSetField (tif, TIFFTAG_IMAGEDESCRIPTION, "3D Simulation");

TIFFSetField (tif, TIFFTAG_COMPRESSION, COMPRESSION_PACKBITS);

         TIFFSetField (tif, TIFFTAG_ROWSPERSTRIP,     16);

         for (row = 0; row < 768; row++)
         {
                 for (int i = 0; i < 1024; i++)
                 {
                         if(row > 234 && row < 530 && i > 350 && i <
700)
                         { // Here I'm trying to draw transparent
green rectangle

                                 buffer[4*i]   = 0;
                                 buffer[4*i+1] = 200;
                                 buffer[4*i+2] = 0;
                                 buffer[4*i+3] = 200; // transparency

                         }
                         else
                         {

                                 buffer[4*i]   = 200;
                                 buffer[4*i+1] = 0;
                                 buffer[4*i+2] = 0;
                                 buffer[4*i+3] = 0;

                         }
                 }
                 TIFFWriteScanline(tif, buffer, row, 0);
         }
         TIFFClose(tif); tif = NULL;
         return 0;
}