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TIFF and LibTiff Mail List Archive

Thread

2006.09.15 12:38 "[Tiff] is there alpha component present in Grayscale or Palette color image", by Anurag Singh
2006.09.15 15:49 "Re: [Tiff] is there alpha component present in Grayscale or Palettecolor image", by Gerben Vos
2006.09.15 17:37 "Re: [Tiff] is there alpha component present in Grayscale or Palettecolor image", by Bob Friesenhahn
2006.09.15 17:46 "RE: [Tiff] is there alpha component present in Grayscale orPalettecolor image", by Ed Grissom
2006.09.15 17:54 "RE: [Tiff] is there alpha component present in Grayscale orPalettecolor image", by Bob Friesenhahn
2006.09.16 09:58 "Re: [Tiff] is there alpha component present in Grayscale orPalettecolor image", by Anurag Singh
2006.09.18 11:23 "Re: [Tiff] is there alpha component present in Grayscale orPalettecolor image", by Gerben Vos
2006.09.16 20:01 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolor image", by Joris Van Damme
2006.09.16 20:47 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolor image", by Bob Friesenhahn
2006.09.16 21:50 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolorimage", by Joris Van Damme
2006.09.16 22:00 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolorimage", by Toby Thain
2006.09.16 22:18 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolorimage", by Joris Van Damme
2006.09.16 22:20 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolorimage", by Toby Thain
2006.09.16 22:38 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolorimage", by Joris Van Damme
2006.09.17 02:07 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolorimage", by Graeme Gill
2006.09.17 08:49 "Re: [Tiff] is there alpha component presentin GrayscaleorPalettecolorimage", by Joris Van Damme
2006.09.17 09:03 "Re: [Tiff] is there alpha component presentin GrayscaleorPalettecolorimage", by Joris Van Damme
2006.09.17 10:39 "Re: [Tiff] is there alpha component presentin GrayscaleorPalettecolorimage", by Graeme Gill
2006.09.17 17:23 "Re: [Tiff] is there alphacomponent presentin GrayscaleorPalettecolorimage", by Joris Van Damme
2006.09.18 01:35 "Re: [Tiff] is there alphacomponent presentin GrayscaleorPalettecolorimage", by Graeme Gill
2006.09.18 09:40 "Re: [Tiff] isthere alphacomponent presentin GrayscaleorPalettecolorimage", by Joris Van Damme
2006.09.18 14:39 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolorimage", by Gerben Vos
2006.09.18 11:06 "Re: [Tiff] is there alpha component present in Grayscale orPalettecolor image", by Gerben Vos

2006.09.15 17:37 "Re: [Tiff] is there alpha component present in Grayscale or Palettecolor image", by Bob Friesenhahn

I'm trying to handle tiff images with alpha component, so i want to know that any tiff image which is Grayscale or Palette color can have alpha component.

It is possible for greyscale, just use the ExtraSamples tag as defined in section 18 of the TIFF spec. It is not possible for palette images; the ColorMap tag uses a fixed format with exactly three values per entry.

I would not go so far as to say it is not possible to have an alpha channel with a Palette-based image. It does seem to be quite possible, albeit rather inconvenient/senseless if associated alpha is used. I don't recall if I have ever written such an image and I have certainly never seen one in the real world. It is correct that the color Palette itself can not contain the alpha information.

Bob
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Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/