Test suite for GIF containing images using rarely used features

Question

The specifications (plural, since there are versions 87a and 89a) of the GIF graphics format are easy to find in the internet (for those who don't want to google:

• http://www.w3.org/Graphics/GIF/spec-gif87.txt
• http://www.w3.org/Graphics/GIF/spec-gif89a.txt)

As you can see in the specification GIF has support for some features that I have never seen used; I only want to give two examples (for simplicity from GIF 89a): - Plaintext extension: on http://www.vias.org/pngguide/chapter11_15.html there is a little bit more detailed documentation - Pixel Aspect Ratio: see section 18. Logical Screen Descriptor. of GIF 89a specification

On the other hand, for PNG there seem to be lots of test images available: http://www.libpng.org/pub/png/pngmisc.html (scroll down); the most common one is the official PNG test suite http://www.schaik.com/pngsuite/ that is also mirrored at http://www.libpng.org/pub/png/pngsuite.html.

What I am looking for is a test suite of GIF images that also/especially contains images using features that are rarely used or often implemented in a wrong way.

The best results that I could find in the internet are the following:

• Images linked from http://en.wikipedia.org/w/index.php?title=Graphics_Interchange_Format - among them images using some not-so common GIF features
• http://phil.ipal.org/tc217.gif (as an example how to use 24 bit depth in GIF files) - linked from http://phil.ipal.org/tc.html and referenced in http://en.wikipedia.org/w/index.php?title=Graphics_Interchange_Format&oldid=411332804#cite_note-8)
• The file http://www-eng-x.llnl.gov/documents/a_image.gif (referenced in http://www-eng-x.llnl.gov/documents/tests/gif.html) claims this to be a test image; for me it rather looks like it is from a time when GIF support was not common in browsers
• Under http://www.fileformat.info/format/gif/sample/index.htm there are files called "GIF Sample Files"; it doesn't look to me that they use more than the "very common" features of GIF

So I could find nothing fullfilling the above stated criterion of a test suite of GIF images also/especially containing features that are rarely used or often implemented in a wrong way.

So: do you know of such a test suite?

Answer 1

I was searching for the same thing and came across this page:

http://code.google.com/p/imagetestsuite/

It contains test suites for PNG/GIF/JPEG/TIFF created so that they try to achieve maximum amount of code coverage with the least amount of images based on the open source decoder code-bases. The idea seems good, but I have not yet had time to check out the actual images.