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TIFF and LibTiff Mail List Archive

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1997.05.08 13:50 "CCITT Group 4 compression and 256 Colors", by Sanjay G. Prabhudesai
1997.05.08 21:05 "Re: CCITT Group 4 compression and 256 Colors", by Gregory W Cook
1997.05.08 21:06 "Re: CCITT Group 4 compression and 256 Colors", by Daniel McCoy
1997.05.09 15:27 "To ALL TIFF MAILING LIST MEMBERS", by Sanjay G. Prabhudesai
1997.05.12 05:44 "Re: To ALL TIFF MAILING LIST MEMBERS", by Rainer Wiesenfarth

1997.05.08 13:50 "CCITT Group 4 compression and 256 Colors", by Sanjay G. Prabhudesai

Hello,

It's me again. I am stuck with a problem. In my previous mails, I had enquired about this problem and I had got quite a few responses. However, I am facing a problem right now and I am in need of the solution urgently.

The problem is that when libtiff is used, and the image being created uses Group 4 compression, then it does not convert to TIFF file. It gives a message

"For Group 3/4 compression, bits per sample must be 1".

However, bits/samples is 4/8 for color images as provided by the TIFF 6.0 specs. Also, specs says that the Group 4 compression can be used only for bilevel, and not for the color images. In this situation, can I compress the image using Group 4 compression?

Also, is there any way out on this perticular situation?

Also, one of the responses received by me last time suggested that this is possible, but the compressed image size is very large compared to the original image size. But I feel that is NOT the better alternative.

Please extend your help in this situation.

regards,

Sanjay Prabhudesai