qjpegrest - an interactive JPEG decoder with restoration algorithms

What are we trying to solve?

Most JPEG decoders (internal in many computer programs) decode the JPEG images in a quick-and-simple way, giving some typical noise problems. Some of those problems may be reduced on post processing, but if we use noise reduction techniques inside the JPEG decoder, we can take profit of all the JPEG information, instead of only the conventionally decoded image.

Here you have a restoration example from a low quality JPEG:

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What does qjpegrest provide?

Trying to collect the state of the art of the JPEG restoration algorithms, I found the next evidences:

• There was no free-to-use implementation of the most promising algorithms
• The best restorations should be obtained mixing algorithms
• Almost every different image required different parameters and algorithms to get a good restoration
• Every user has a different opinion on what restoration is the best

Therefore, I thought I could provide some software which:

• Has the implementation of different JPEG restoration algorithms (here is the bibliography related to this work)
• Allow the combination of different state of the art algorithms
• Someone understanding the JPEG decoding finds the program easy to use
• The user can easily try different parameters or algorithms and compare
• The user can use mathematical measures to have some objective comparisions
• The program should be portable and reusable for free on different platforms

How does the program look like, and how to use it

Look at some screenshots.

I still have not written any manual in English. You should better look at the example video (15MB, DivX, without audio), and send me a letter if you don't understand something. Oh, you may not be able to guess that Control+LeftClick and Control+RightClick alllow the image zooms.

Compilation requirements

On Linux and Macintosh OS X:

• cmake at least 2.4 to create the Makefiles
• Qt at least 4.3, for the UI library
• IJG's libjpeg v6b, to access the JPEG data structures
• GNU C++ compiler - I used 3.4.4 on Linux.

Download

Download the latest version (GPLv2 licensed, taking some bits from MegaWave 2): qjpegrest-0.5.tar.gz - v0.5 (around 100KB)

You can download a Linux 2.6 dynamic executable which requires Qt 4.3 and libjpeg: qjpegrest-0.5.gz - v0.5 (around 190KB)

You can download a MacOSX static executable: qjpegrest-0.5.dmg - v0.5 (around 4MB)

Thanks to

• My university director related to this project, Josep Maria Aroca
• Jacques Froment, provider of C code from MegaWave 2, for the method Adapted Total Variation for Artifact Free Decompression of JPEG Images