Image Depth

Usage

Starting with version 2.0, you can simply specify which pixel bit depth you want to use when starting a session:

xpra start --pixel-depth=30

Support for each subcommand:

• "xpra start" supports bit depths 16,24 and 30
• "xpra start-desktop" supports 8,16,24 and 30
• "xpra attach" supports 16,24,30,48 (with xpra version 2.1 or later only)

Testing that high bit depth is in use can be tricky, for that we provide a test application: #1553.

Limitations

• transparency is supported in 24-bit mode, which is in effect a 32-bit mode
• 30-bit rendering is only supported in the opengl enabled client (the operating system and display must be configured for deep colour support), with opengl disabled the data will always be downsampled
• only the "rgb" encoding will preserve high bit depth at present
• the other encodings will downsample 30-bit to 24-bit before compression
• 16-bit mode has no native encoders and so the pixels are upsampled to 24-bit before compression which is wasteful
• 8-bit mode is not optimized
• see wiki/Colourspace

Links

• #1445: 8-bit server support
• #1315: 16-bit server support
• #909: 30-bit server support
• #1309: 30-bit client support
• #1584: HDR / Deep Color support in X11
• ​10-bit Color Visual Support Lands In Mesa

Codec support for 10 bit per pixel (aka 30 bit):

• #1441: EXR codec
• #1310: vpx
• #1308: nvenc
• #1462: x264