# coding=utf-8 Tiffany - Read/Write Multipage-Tiff with PIL without PIL ======================================================== Tiffany stands for any tiff. The tiny module solves a large set of problems, has no dependencies and just works wherever Python works. Tiffany was developed in the course of the *DiDoCa* project and will now appear on PyPi. Abstract ======== During the development of *DiDoCa* (Distributed Document Capture) we were confronted with the problem to read multipage Tiff scans. The GUI toolkit *PySide (Qt)* does support Tiff, but only shows the first page. We also had to support Fax compression (CCITT G3/G4), but *Qt* supports this. As a first approach we copied single pages out of multi-page tiff files using *tiffcp* or *tiffutil* (OS X) as a temp file for display. A sub-optimum solution, especially for data security reasons. The second approach replaced this by a tiny modification of the linkage of the tiff directories (IFD). This way, a tiff file could be patched in memory with the wanted page offset and then be shown without any files involved. Unfortunately also this solution was not satisfactory: - out tiff files have anomalies in their tiff tags like too many null-bytes and wrong tag order, - Qt's implementation of tiff is over-pedantic and ignores all tags after the smalles error. Being a good friend of *Fredrik Lundh* and his *PIL* since years, I tried to attach the problem using this. Sadly Fredrik hasn't worked much on this since 2006, and the situation is slightly messed up: *PIL* has a clean-up of tiff tags, but cannot cope with fax compression by default. There exists a patch since many years, but this complicates the build process and pulls with *libtiff* a lot of dependencies in. Furthermore, *PIL* is unable to write fax compressed files, but blows the data up to the full size, making this approach only a half solution as well. After a longer odyssey I saw then the light of a Tiffany lamp: I use only a hand-full of *PIL*s files, without any modification, pretend to unpack a tiff file, but actually cheating. Only the tiff tags are nicely processed and streamlined, but the compressed data is taken unmodified as-is. When writing a tiff page out, the existing data is just assembled in the correct order. For many projects like *didoca* that are processing tiff files without editing their contents, this is a complete solution of their tiff problem. The dependencies of the project stay minimal, there are no binaries required, and Tiffany is with less than 300 lines remarkably small. Because just 5 files from *PIL* are used and the _imaging module is not compiled at all, I'm talking about "PIL without PIL" ;-) Tiffany is a stand-alone module and has no interference with *PIL*. You can see this by looking at ``import_mapper.py``. This module modifies ``__import__`` so that the *PIL* modules appear as top-level internally, but become sub-modules of tiffany in ``sys.modules``. Please let me know if this stuff works for you, and send requests to <tismer@stackless.com> or use the links in the bitbucket website: https://bitbucket.org/didoca/tiffany cheers -- Chris -- Christian Tismer :^)<mailto:tismer@stackless.com> tismerysoft GmbH : Have a break! Take a ride on Python's Karl-Liebknecht-Str. 121 : *Starship* http://starship.python.net/ 14482 Potsdam : PGP key -> http://pgp.uni-mainz.de work +49 173 24 18 776 mobile +49 173 24 18 776 fax n.a. PGP 0x57F3BF04 9064 F4E1 D754 C2FF 1619 305B C09C 5A3B 57F3 BF04 whom do you want to sponsor today? http://www.stackless.com/