[Image-SIG] IOError: decoder group3 not available
D. Alan Stewart
Mon, 21 Apr 2003 13:11:32 -0400
From what you've said it sounds like your TIFF has 1-bit per pixel
images compressed, Group 3/4 compressed. You would need to decompress
eash image, convert it to 8-bit per pixel grayscale (which will be 8
times the size of the original uncompressed image; RGB would be 24 times
the original size), and then JPG compress it. I doubt this will produce
a compressed image smaller than the Group 3 image you have now. The
PDF specification supports Group 3 image compression, why not just
transfer the compressed image as is to the PDF and not hassle with all
this? See section 3.3.5 of the 1.4 PDF Specification for a description
of the CCITTFaxDecode filter....
David Thibault wrote:
>I've got multipage TIFF files that I need to convert to PDF using PIL and
>reportlab. I think I'd be all set except I seem to be hitting an old bug.
>I saw this:
>http://mail.python.org/pipermail/image-sig/2002-February/001736.html and it
>seems to be the exact problem I'm running into. Has anyone ever figured
>this out? These tiff's are mode 1 and I get the exact error in the subject
>line if I try to convert them to RGB or if I try to convert them to JPG. I
>was hoping to take each tiff, pull out each page, convert it to jpg, then
>add it to the PDF file so that it would minimize the size of the files.
>However, anything that will work programmatically will make me happy...
>Image-SIG maillist - Image-SIG@python.org
D. Alan Stewart
Senior Software Developer
Layton Graphics, Inc.
Marietta, GA U.S.A.