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2008.02.03 11:07 "Re: Problem with large tiff images", by Joris Van Damme
Jean-Michel,
Jean-Michel FRECINAT wrote:
> I am a developer in c# and c++ and i am working on tiff images. But
> i am a problem when i try to save image (22000x9000 pixels and
> 30000x10000 pixels) i have an error "No space to output buffer".
> How to save a large tiff file with libtiff?
> I use :
>
> unsigned char* scanline_data = (unsigned
> char*)_TIFFmalloc(exportWidth*spp*sizeof(unsigned char));
>
> if(scanline_data != NULL)
> {
> for(unsigned long row= 0 ; row < height ; row++)
> {
> memcpy(scanline_data,raster+row*exportWidth*spp,exportWidth*spp);
> TIFFWriteScanline(output,scanline_data, row,0);
> }
>
> _TIFFfree(scanline_data);
> }
> TIFFFlush(output);
> TIFFClose(output);
> _TIFFfree(raster);
Since you use the Scanline interface, you're likely writing a strip TIFF or
this wouldn't succeed at all. Bear in mind that some stages in LibTiff may
require buffers as large as one complete strip, though that may depend on
the compression mode selected. Though it's not clear if you do any error
checking, what tags you set with what values, and at what point exactly the
error occurs, this might very well be related to your problem as you might
be writing this as a single strip image.
So make sure you set the RowsPerStrip tag to an appropriatelly small value.
A good value might be 10 or so, as 10*30000*4, with 30000 being about the
highest width you have in mind, and 4 being a typical average bytesize of a
pixel depending on your colourspace setting, is 1200000, is roughly about a
bit more then a megabyte. That's not too much so as to not get large stalls
on buffering decoders, and in the first place it will not get you into
unscalable trouble in buffering encoders, and it's not too little such that
the overhead in various places that comes from the division into strips is
still negligable. If you're using JPEG compression, you might want to select
a value of 16 instead, as that'll likely correspond to the height of a JPEG
MCU if you use default subsampling values and result in efficient
compression.
Best regards,
Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
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