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2010.05.10 11:40 "Re: Tiff Digest, Vol 72, Issue 4", by Weichao Wang

If the small component images are all of the same size, consider to generate
the large image in tiled format. As long as I remember, the format
specification does not require the scan lines of a tile to end at a byte
boundary (but I'm not quite sure). If a scan line of a tile must always
padded to a byte boundary, the matter would be quite simple for you. 

Weichao Wang
 
> From: tiff-request@lists.maptools.org
> Subject: Tiff Digest, Vol 72, Issue 4
> To: tiff@lists.maptools.org
> Date: Sun, 9 May 2010 12:00:02 -0500
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> Today's Topics:
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> 1. Merge several TIFFG4 images (Oliver Geisen)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Sat, 8 May 2010 20:39:00 +0200
> From: Oliver Geisen <O.GEISEN@VR-WEB.DE>
> Subject: [Tiff] Merge several TIFFG4 images
> To: tiff <tiff@lists.maptools.org>
> Message-ID: <E5B0C174-1C95-43DE-9FE2-0409F20DDEF0@VR-WEB.DE>
> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
> 
> Hello,
> 
> i need to write a tool using libtiff which is able to paste 1 to 10 G4 
> compressed bilevel TIFF images onto a large (17300x27051 pixel) image 
> and save this as G4 compressed image also. The images to be pasted 
> onto the canvas are different in size, but much smaller.
> Now i wonder if it is best to create the big image in memory and write 
> the data of each image to be placed in turn into this memory block, or 
> process it line by line.
> Libtiff itself seems not to provide any image functions itself, but it 
> is the only lib i found which can handle G4 TIFFs natively without 
> converting it into an internal colorspace (which makes them impossible 
> to handle because they grow to several GB in memory).
> What i need is some advice how to start this. One big problem for me 
> is bit-shifting. If an image to be placed does not start on a byte 
> boundary, i need to shift all pixels (bits) of a row, line by line. 
> This may take a long time and i really don't know how to code this 
> efficiently in C.
> The tool must be very very fast, so i merging does not take longer 
> than several seconds.
> 
> Any help is appreciated here!
> 
> 
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> End of Tiff Digest, Vol 72, Issue 4
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