Image Depth

Simply specify which pixel bit depth you want to use when starting a session, ie: ```shell xpra seamless --pixel-depth=30 ``` * [seamless mode](../Usage/Seamless.md) supports bit depths 16,24 and 30 * [desktop mode](../Usage/Desktop.md) supports 8,16,24 and 30 * the native client `xpra attach` supports 16,24,30,48

Testing that high bit depth is actually in use can be tricky, for that the xpra toolbox provides a test application.

* the operating system and display must be configured for deep colour support * transparency is supported in 24-bit mode, which is in effect a 32-bit mode * with versions older than 4.1, 30-bit rendering is only supported in the [opengl enabled client](../Usage/Client-OpenGL.md), and only the `rgb` encoding will preserve high bit depth * 16-bit mode has no real native encoders and so the pixels are often upsampled to 24-bit before compression which is wasteful * 8-bit mode is not optimized at all * see also [DPI](DPI.md) * [#1445](https://github.com/Xpra-org/xpra/issues/1445): 8-bit server support * [#1315](https://github.com/Xpra-org/xpra/issues/1315): 16-bit server support * [#909](https://github.com/Xpra-org/xpra/issues/909): 30-bit server support * [#1309](https://github.com/Xpra-org/xpra/issues/1309), [#2839](https://github.com/Xpra-org/xpra/issues/2839): 30-bit client support * [#2828](https://github.com/Xpra-org/xpra/issues/2828): 30-bit opengl rendering of video output * [#1584](https://github.com/Xpra-org/xpra/issues/1584): HDR / Deep Color support in X11 * [10-bit Color Visual Support Lands In Mesa](https://www.phoronix.com/scan.php?page=news_item&px=Mesa-Lands-10-bit-Color) Codec support for 10 bit per channel (aka 30 bit): * [#1441](https://github.com/Xpra-org/xpra/issues/1441): EXR codec * [#1310](https://github.com/Xpra-org/xpra/issues/1310): vpx * [#1308](https://github.com/Xpra-org/xpra/issues/1308): nvenc * [#1462](https://github.com/Xpra-org/xpra/issues/1462): x264