2005.08.17 16:04 "RE: [Tiff] Re: TIFFWriteScanline and G4 compressed block concatenation", by Philip Watkinson

Joris,

I was unable to create a valid CCITT Group 4 image file by concatenating the strips from a CCITT Group 4 TIFF file.

Philip

-----Original Message-----

From: Joris [mailto:joris.at.lebbeke@skynet.be] Sent: Wednesday, August 17, 2005 10:37 AM To: Philip Watkinson; 'TIFF mailing list' Subject: Re: [Tiff] Re: TIFFWriteScanline and G4 compressed block concatenation

You can extract a CCITT Group 4 image from a TIFF file with TIFFReadRawStrip() and create a valid CCITT Group 4 image file provided the image only uses one strip.

Indeed. I hadn't noticed there was ever any doubt about that.

I want to extract a CCITT Group 4 image from a TIFF file. If I

obtain the strip offsets using TIFFGetField(), can I concatenate the

strips together to create a valid CCITT Group 4 image file?

A good way to find out is to try. I'm not enterily sure and would have to double-check, but I don't think you can do that. Two CCITT group 4 compressed blocks, concatenated, is not one valid block I think.

Have you double-checked my suspicion? If so, it would be interesting to read your findings.

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