2004.07.11 18:57 "Re: [Tiff] sampleper pixel", by Frank Warmerdam

I am balint and I have some question concerning tiff and libtiff. I have a tiff picture.This picture was made such that there was a measurment where single photons fell into the pixels of a detector and thus we got a matrix of (let's say) float or int data in each matrix element.Then we saved the picture in .tiff format.There are only one directories in each tiff file.I have a simple question:how can I read the data of each pixels from the file?Because what I don't understand in libtiff is that I can read the file following the "scanline" method to a buf:

    buf = _TIFFmalloc(TIFFScanlineSize(Tif));
     for (int row = 0; row < ImageHeight; row++){
      TIFFReadScanline(Tif, buf, row);
        "reading the buff somehow";
      }

but the problem is that I cannot get the single (let's say float or int type) datas of single pixels from the buff array.

Balint,

If the file has one sample per pixel and is of type float (4 bytes per pixel, sampleformat ieeefloat) then you would do something like this:

      buf = _TIFFmalloc(TIFFScanlineSize(Tif));
      for (int row = 0; row < ImageHeight; row++){
        TIFFReadScanline(Tif, buf, row);
        "reading the buff somehow";
        for( int pixel = 0; pixel < ImageWidth; pixel++ ) {
           printf( "value[%d,%d] = %f\n",
                   pixel, row, ((float *) buf)[pixel] );
        }
      }

Best regards,

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