libKPEG

A simple, easy-to-use JPEG library, written in C++11.

This is a work in progress. Expect loads of bugs. There are no dependencies to build this project.

Only the decoder has been implemented till now. libKPEG decodes a JFIF image file and saves the uncompressed image to a PPM image in the same directory and while encoding, takes as input a PPM image file and converts it to a corresponding JFIF file.

My goal of writing this library is to gain a better technical knowledge about JPEG image compression and also a self learning programming exercise. I have intentionally used naive programming constructs for better clarity, sacrificing speed.

NOTE: Only 8-bit Sequential Baseline DCT, grayscale/RGB, with no chroma subsampling (4:4:4) is supported as of now.

Features Supported

Encoder

• Half complete, not yet functional.

Decoder

• 8-bit Sequential Baseline, DCT, grayscale/RGB, no chroma subsampling (4:4:4)

Building

$ git clone https://github.com/TheIllusionistMirage/libKPEG
$ git mkdir build && cd build
$ cmake ..
$ make

Usage

Print help

$ ./kpeg -h

Decompress a JPEG file to uncompressed PPM format

To convert a JPEG image file called some-image.jpg to its corresponding uncompressed PPM form:

$ ./kpeg some-image.jpg

A PPM image file called some-image.ppm will be created in the same directory as the some-image.jpg.

NOTE

Most images should work without any problems. And if some don't, they will eventually. You can check out the misc/screenshots directory for some screenshots I took with test images.

Reference materials

1. The official JPEG standard, ITU-T.81 (pdf)
2. The official JFIF standard (pdf )
3. Calvin Hass' excellent articles (blog posts)
4. Cristi Cuturicu's JPEG Guide (txt)

Author

Koushtav Chakrabarty ( aka TheIllusionistMirage )

License

Not decided yet