01-10-11 - Perceptual Metrics Warmup - JPEG Settings

This is a repeat of old info, just warming up the new system and setting baselines.

Our JPEG is just regular old IJG JPEG with various lossless recompressors ; results on PDI :

As seen before, PAQ has some screwups at low bitrate but is otherwise very close to packjpg, and flat quantization matrix is obviously best for RMSE but worse for visual quality ("flat" here is flat + pack).

From now on we will use jpg_pack as the reference point.