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September 2006
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2006.09.18 11:23 "Re: alpha in Grayscale or Palette", by Gerben Vos
Anurag Singh wrote: > > then how will i get extra data plane in palette images. I want all > image data so please let me know how can i get it. Please read the libtiff manual, then ask a more specific question. > So what should i understand?? i am getting that grayscale and palette > both can have extra component. am i rt? Yes, you can set the ExtraSamples tag to 1 and just add the extra sample for each pixel to the image data. The first sample for the pixel would be either the greyscale value or the index into the palette, the second would be the alpha value. Please note that it is defined as associated alpha (read the TIFF spec for explanation, or for example the PNG spec, which explains why they didn't use it), which is hard to use, or even just useless when used with a palette. Gerben.