LibTiff Mailing List

Flávio,

Flávio Tiba wrote:
> I am a new user of libtiff library and I have some doubts. I am
> developing a program to read a tiff file G3 and I need to clear the
> last white lines from file, I would like to know what api can I
> use?

It is not clear to me what you mean. You could mean either

- Changing the decompressed memory, i.e. not changing the actual file at
all. This is extremely easy.

- Transcoding, i.e. having a decompressor feeding a compressor, except
that the last few lines of 'food' are to be changed in the process. This
is easy.

- Same transcoding scheme applied to a single strip, in a single file,
i.e. decompressor feeds a compressor that writes a replacement for the
old strip back into the original file. This is probably still feasable.

- Changing actual encoded compressed data in a strip, so as to clear the
last lines in that strip, without changing anything else in the file.
This is possible in the case of G3 compression, I think, since the
compressed data for the cleared lines will be smaller or equal in size
to what was there given the G3 compression, and the lines are the last
ones, so the data block becomes a little shorter and only the
StripByteCount has to be adjusted to reflect that. It is the hardest
option though, and a good knowledge of G3 compression is required.

- Or perhaps, by 'clearing the last white lines', you mean that you
actually want to get rid of these lines alltogether, decrementing image
height?

Could you please explain which, if any, of the above guesses is what you
are after?

Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
Download your free TIFF tag viewer for windows here:
http://www.awaresystems.be/imaging/tiff/astifftagviewer.html


AWARE [SYSTEMS]		Imaging expertise for the Delphi developer
		TIFF and LibTiff Mailing List Archive
	LibTiff Mailing List TIFF and LibTiff Mailing List Archive September 2005 Previous Thread Next Thread Previous by Thread Next by Thread Previous by Date Next by Date Contact The TIFF Mailing List Homepage This list is run by Frank Warmerdam Archive maintained by AWare Systems	Thread 2005.09.19 02:47 "How can I remove the last white lines?", by Flávio Tiba 2005.09.19 06:32 "Re: How can I remove the last white lines?", by Joris Van Damme 2005.09.19 06:35 "Re: How can I remove the last white lines?", by Joris Van Damme 2005.09.19 06:32 "Re: How can I remove the last white lines?", by Joris Van Damme Flávio, Flávio Tiba wrote: > I am a new user of libtiff library and I have some doubts. I am > developing a program to read a tiff file G3 and I need to clear the > last white lines from file, I would like to know what api can I > use? It is not clear to me what you mean. You could mean either - Changing the decompressed memory, i.e. not changing the actual file at all. This is extremely easy. - Transcoding, i.e. having a decompressor feeding a compressor, except that the last few lines of 'food' are to be changed in the process. This is easy. - Same transcoding scheme applied to a single strip, in a single file, i.e. decompressor feeds a compressor that writes a replacement for the old strip back into the original file. This is probably still feasable. - Changing actual encoded compressed data in a strip, so as to clear the last lines in that strip, without changing anything else in the file. This is possible in the case of G3 compression, I think, since the compressed data for the cleared lines will be smaller or equal in size to what was there given the G3 compression, and the lines are the last ones, so the data block becomes a little shorter and only the StripByteCount has to be adjusted to reflect that. It is the hardest option though, and a good knowledge of G3 compression is required. - Or perhaps, by 'clearing the last white lines', you mean that you actually want to get rid of these lines alltogether, decrementing image height? Could you please explain which, if any, of the above guesses is what you are after? Joris Van Damme info@awaresystems.be http://www.awaresystems.be/ Download your free TIFF tag viewer for windows here: http://www.awaresystems.be/imaging/tiff/astifftagviewer.html

LibTiff Mailing List

Thread

2005.09.19 06:32 "Re: How can I remove the last white lines?", by Joris Van Damme