Is there a reason not to offer LZW compression for Tiff exports in darktable?

Software
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My Canon Pinter software can not read the deflate tiff compression from DT. If I open the tiff file in GIMP and resave with LZW compression there is no problem. Also no problem if the DT export is not compressed. I presume this is the same issue identified for Epson printers a few days ago. Tiff export compression

Is there a reason LZW is not an option in darktable or should I post a feature request?

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It is not supported by libtiff (i.e. it was removed some time ago). LZW was patented (maybe expired since?) so not a good match for open source software.

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Ah, it was restored in libtiff after the patent expired, but at that point I guess people stopped caring and moved on to deflate/zip. In addition, LZW does not work on 16-bit TIFFs.

You can use the libtiff tiffcp utility to batch convert your deflate TIFFs to LZW TIFFs.

4

Is there a reason you can’t ask Canon to support deflate first? You paid for that product after all. :wink:

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Canon have made some strange choices with their software offerings. They used to have a good panorama stitching option and that has disappeared. A shame because it was one of the better ones. It is also not only DT tiffs that don’t open in Canon software, but luckily GIMP has the issue sorted and will open every tiff I throw at it and export a tiff that can be read by Canon. Still it would be nice to have the option of LWZ in darktable but its not a deal breaker for me.

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Doesn’t really answer the question… They have a support channel, no? What was their reply?

As it is theoretically possible, you are of course free to make the feature request, and more than welcome to contribute a pull request directly.

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I appreciate the work that volunteer developers put into DT. They have more important stuff to develop and this is not a deal breaker for me. When I want to print I will open the image in GIMP and then resave the image and all is good. I was just wondering why LZW was not an option. The patent may have once been the reason but GIMP has gotten around that.

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In the meantime, perhaps ImageMagick or similar can be used to recompress the files, as in eg

mogrify  -compress lzw *.tif