difftest_ng : swiss army knife for image format conversion and testing on github

Hi folks,

at

https://github.com/thorfdbg/difftest_ng

you'll find the sources of my "swiss army knife" for image format conversion and imgae compression, available under GPLv3.

Difftest_ng understands manifold lossless image formats and can convert between them (ppm,pbm,pgm,pfm,pfs,bmp,pgx,tif,png,exr,rgbe or raw, with dpx being the latest extension), and allows to measure most simple image metrics: psnr,snr,peak error,mrse, mean error, drift error..., and supports the typical conversions (YCbCr, subsampling, upsampling, clipping, clamping, bitdepth scaling)... that have been useful over the years in my work at the JPEG committee.

It is published at github hoping that others may find it useful, too.