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Akronix
Asked: 2013-12-09 14:12:36 +0800 CST

how can I find out bits per pixel using into my framebuffer?

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I know the X.org server run is executed with certain value of bpp, 8bpp by default i think.

But how can I find out the actual bits per pixel using into my framebuffer while i'm on linux? is there any command that can get it?

Thanks.

graphics

2 Answers

  1. Best Answer

    In a terminal, run the xwininfo command, then choose a window - the Depth: result is the bits per pixel. For example:

    $ xwininfo

xwininfo: Please select the window about which you
          would like information by clicking the
          mouse in that window.

xwininfo: Window id: 0x3e00005 "davidp@sysadmin: ~"

  Absolute upper-left X:  1920
  Absolute upper-left Y:  24
  Relative upper-left X:  0
  Relative upper-left Y:  0
  Width: 1920
  Height: 1056
  Depth: 32
  Visual: 0x74
  Visual Class: TrueColor
  Border width: 0
  Class: InputOutput
  Colormap: 0x3e00004 (not installed)
  Bit Gravity State: NorthWestGravity
  Window Gravity State: NorthWestGravity
  Backing Store State: NotUseful
  Save Under State: no
  Map State: IsViewable
  Override Redirect State: no
  Corners:  +1920+24  -0+24  -0-0  +1920-0
  -geometry 212x56-0-0

    You could also use xdpyinfo, which will give you more information than you probably want - including all available bit depths for your displays (without showing you which one is actually in use).

    • 3

  2. adding an answer since I lack reputation to post a comment to David Purdue's answer..

    As David mentions, xdpyinfo can be used. The advantage over xwininfo is that you don't need to select a window, which can be handy when you are checking a virtual framebuffer created with Xvfb.

    Here is a snippet of the relevant output of the command xdpyinfo:

    ....
screen #0:
  dimensions:    1024x768 pixels (260x195 millimeters)
  resolution:    100x100 dots per inch
  depths (6):    8, 1, 4, 16, 24, 32
  root window id:    0x4d
  depth of root window:    8 planes
  number of colormaps:    minimum 1, maximum 1
  default colormap:    0x20
....

    The depth of root window reflects the bit depth of the root window, in this example it's 8 bits.

    The depths property lists the supported bit depths, the first number indicates the current bit depth.

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