Display Stream Compression

EN Texte en anglais Pas encore d'article dans ta langue : extrait en anglais.

Display Stream Compression (DSC) is a VESA-developed lossy video compression algorithm designed to enable increased display resolutions and frame rates over existing physical interfaces, and make devices smaller and lighter, with longer battery life. It is a low-latency algorithm based on delta PCM coding and YCGCO-R color space. Although DSC is not mathematically lossless, it meets the ISO/IEC 29170 standard for "visually lossless" compression, a form of compression in which "the user cannot tell the difference between a compressed and uncompressed image". ISO 29170 more specifically defines an algorithm as visually lossless "when all the observers fail to correctly identify the reference image more than 75% of the trials". However, the standard allows for images that "exhibit particularly strong artifacts" to be disregarded or excluded from testing, such as engineered test images. Research of DSC using the ISO/IEC 29170 interleaved protocol, in which an uncompressed reference image is presented side by side with a rapidly alternating sequence of the compressed test image and uncompressed reference image, and performed with various types of images (such as people, natural and man-made scenery, text, and known challenging imagery) shows that in most images DSC satisfies the standard's criterion for visually lossless performance, although in some trials participants were able to detect the presence of compression on certain images. DSC compression works on a horizontal line of pixels encoded using groups of three consecutive pixels for native 4:4:4 and simple 4:2:2 formats, or six pixels (three compressed containers) for native 4:2:2 and 4:2:0 formats. A modified version of DSC, VDC-M, is used in DSI-2. It allows for more compression at 6 bit/px at the cost of higher algorithmic complexity. DSC version 1.0 was released on 10 March 2014, but was soon deprecated by DSC version 1.1 released on 1 August 2014.