Different image file format samples

Question

In our own software we support loading of different kind of images, including but not limited to .bmp, .gif, .tiff, .jpg, and .png.

In code I've noticed that some of images might be using color indexing , but it looks like one of our image manipulation library is missing some of patches (lost upon a time).

I would like to test our software against such odd image formats (we are loading .png and .jpg ok), can you recommend me some set of images, where I can download a lot of different image file formats with different saving options.

So color indexed .png's / .tiff's / .bmp's would be included at least.

Answer 1

Although your question is off-topic I want to give you some advice.

Websearch will yield anything useful if something is out there, so asking here doesn't make too much sense.

What you plan to do is: us a random collection of images in various formats and hope that your software will handle them properly.

What do you want to tell your user if your software fails? "Sorry mate that particular use case was not part of the random image collection I found online for testing?"

What you should do: Create test samples for every format your software claims to support. For each supported format make sure you implement a test sample for every aspect of the format specification!

Answer 2

As @piglet suggests, you should create test cases to ensure coverage. You could use something like ImageMagick and here is a very basic script that generates a bunch of files in different formats - much more is possible, of course, but you need to specify your own test cases.

This creates a test JPEG file:

magick xc:red xc:lime +append \( xc:blue xc:magenta +append \) -append -resize 600x600 test.jpg

Here is a script if you want a variety of formats:

#!/bin/bash
files=(test.gif test.jpg test.bmp PNG8:testPNG8.png PNG24:testPNG24.png PNG32:testPNG32.png PNG48:testPNG48.png PNG64:testPNG64.png test.tif)

for f in "${files[@]}"; do
   magick xc:red xc:lime +append \( xc:blue xc:magenta +append \) -append -resize 600x600 "$f"
done

And here are the output files:

-rw-r--r--@ 1 mark  staff  1080138 14 Sep 09:26 test.bmp
-rw-r--r--@ 1 mark  staff   109366 14 Sep 09:26 test.gif
-rw-r--r--@ 1 mark  staff    24457 14 Sep 09:26 test.jpg
-rw-r--r--@ 1 mark  staff  2160264 14 Sep 09:26 test.tif
-rw-r--r--@ 1 mark  staff    62181 14 Sep 09:26 testPNG24.png
-rw-r--r--@ 1 mark  staff    68153 14 Sep 09:26 testPNG32.png
-rw-r--r--@ 1 mark  staff   545890 14 Sep 09:26 testPNG48.png
-rw-r--r--@ 1 mark  staff   550337 14 Sep 09:26 testPNG64.png
-rw-r--r--@ 1 mark  staff     6747 14 Sep 09:26 testPNG8.png

And here are all the test images montaged together:

You probably need to cycle through:

• formats,
• bit depths (8,16,32),
• colourspaces,
• palettised/non-palettised,
• transparent/opaque,
• compression types,
• interlaced/non-interlaced,
• ... and so on

Answer 3

I did some searching, but I didn't find any comprehensive image format test archive; what I did find was limited:

• https://code.google.com/archive/p/imagetestsuite/downloads
• https://wiesmann.codiferes.net/share/bitmaps/
• https://www.w3.org/People/mimasa/test/imgformat/
• https://commons.apache.org/proper/commons-imaging/sampleimages.html
• Test suite for GIF containing images using rarely used features

I suspect that another place to look would be the test images used for the build tests (CI testing) for an open source project: an image using project (like Chromium or Firefox) or a multi-format image processing library (like ImageMagick).

Things the image library should include at least:

• Wide variety of formats (modern and obsolete; vector, animated, 3d and raster; image depth and colour spaces etc)
• Malformed files with invalid data structures (variety for each format, including existing malware, truncated files)
• Polyglot files - a file that is simultaneously an image file and another file type (gifar, discussion, thinkfu)
• DoS files, causing either excessive CPU (recursive image format) or excessive memory usage (e.g. highly compressed black image with insanely big dimensions)
• Formats with different meta data including invalid meta data (e.g. EXIF malware)

I can find good examples of test suites for each particular format (e.g. png, bmp)