Project web site, libjpeg is a C library for compressing and decompressing JPEG images.

• On a Core 2 Duo E6300 it takes 1.5ms to compress a 160×120 RGB image, 0.6ms for 72×88, 0.06ms for 32×24.

• Has a rather weird OO-style system implemented in C for customizing the behaviour.
• The default compressor and decompressor work only for file descriptors, to do in-memory you need to write 5-6 functions of your own.

• Read the documentation and the example code that comes with libjpeg, you're going to need it.
• When compressing, you can pass in an array of pointers to the same string as the scanlines array, so there's no need to copy data.
• If you use setjmp/longjmp in your error handler, you can add the jump target to cinfo→client_data.

• stb_image.c - a small self-contained C lib for decompressing JPEG and PNG images

• W3C's JPEG page