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TIFF and LibTiff Mail List Archive

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2008.04.17 09:58 "[Tiff] a question about creating transparency of the image in TIFF", by Константин_Луцкий
2008.04.17 14:03 "Re: [Tiff] a question about creating transparency of the image in TIFF", by Frank Warmerdam
2008.04.17 15:18 "Re: [Tiff] a question about creating transparency of the image in TIFF", by Gerben Vos
2008.04.17 21:14 "Re: [Tiff] a question about creating transparency of the image in TIFF", by Chris Cox
2008.04.17 21:48 "Re: [Tiff] a question about creating transparency of the image in TIFF", by Bob Friesenhahn
2008.04.18 12:53 "Re: [Tiff] a question about creating transparency of the image in TIFF", by Edward Lam
2008.04.18 15:41 "Re: [Tiff] a question about creating transparency of the image in TIFF", by Bob Friesenhahn
2008.04.18 15:56 "Re: [Tiff] a question about creating transparency of the image in TIFF", by Edward Lam

2008.04.17 21:14 "Re: [Tiff] a question about creating transparency of the image in TIFF", by Chris Cox

There are 2 types of alpha in TIFF: associated (transparency) and unassociated (undefined extra channels).

Also, the TIFF spec. states that images with associated alpha (transparency) must be premultiplied.

Chris

On 4/17/08 8:18 AM, "Gerben Vos" <Gerben@zylab.com> wrote:

Константин Луцкий wrote:

Hi. Can anyone help me? How can I create transparency of the image in TIFF?

Frank Warmerdam wrote:

The conventional approach is to create an alpha sample for each pixel, and set it to indicate transparent pixels.

For example, for RGB images (PhotometricInterpretation = 2) you can set SamplesPerPixel to 4, and then indicate in the ExtraSamples tag that the extra (fourth) sample is an alpha channel. Read the TIFF specification for more info.