VESA DisplayPort 1.4 Display Stream Compression (DSC)

[Sportman]

"DP 1.4 is also the first DP standard to take advantage of VESA’s Display Stream Compression (DSC) technology. DSC version 1.2 transport enables up to 3:1 compression ratio and has been deemed, through VESA membership testing, to be visually lossless."
http://www.vesa.org/featured-article...d-version-1-4/

Is DSC 1.2 visually lossless in all cases?

[Cyan]

As far as I know, yes.
Only "pathological" (pure noise) cases will suffer, and since it means the source was not coherent, the distorted result is no more "visually" worse than the input.

There are multiple compression modes, which complement each other pretty well.
One is fairly good for smooth transitions, like photo/films, one is fairly good for a low number of contrasted colors, like fonts.
The predictor can quickly switch between modes.

[thorfdbg]

As far as I know, yes.

At least in all cases we - as JPEG - tested with. While JPEG was not (or only partially) involved in the design of the algorithm, it was involved in the design of the tests. The test protocol for visually lossless compression is an ISO standard by now (ISO/IEC 29170-2) and it contains a set of challenging example images (natural, computer-generated, mixed graphics/raster content). Tests for visually lossless includes a side-by-side comparison where one side is the original, and the other side consists of a "flicker test", i.e. where the original interchanges with the reconstructed image with a frequency of about 10Hz. This sort of test is very sensible for any type of defects - everything that looks different then flickers. This DSC algorithm is a starting point for a new standardization initiative, JPEG XS, which will be a light-weight, visually lossless compression for (mostly) IP transport of images and image sequences. Details on this are found on www.jpeg.org. For example, click on the proceedings of the JPEG XS workshop.