ATI oss color space compressed in the dark shades of gray

Sebastian Schultz sebastian2.schultz at
Thu Mar 13 03:34:13 PDT 2014

Is there anything I can do to about it? Or is this an upcoming feature? Or is 
it a bug and I should submit a report?


Am Mittwoch, 12. März 2014, 12:18:37 schrieb Alex Deucher:
> On Wed, Mar 12, 2014 at 10:31 AM, Sebastian Schultz
> <sebastian2.schultz at> wrote:
> > Hello,
> > 
> > first of all: I'm using a Radeon 7750 in combination with a monitor via
> > display port and a tv via the HDMI port. Most of the time I do not want a
> > picture on the tv, only when wathcing videos, so I use xrandr scripts to
> > switch that display on and off. And here comes my problem:
> > 
> > With the arrival of linux 3.13 to the [core]-repo of arch linux I switched
> > from catalyst to the open source drivers, as they finally provide a
> > sufficient performance. My only problem now is that the colorspace is
> > compressed for gray values below 16 (that means every shade of gray
> > having values of 0 to 16 look just black). That's only the case for my
> > HDMI-output connected to my TV, which worked without problems with the
> > catalyst drivers. Also, only the dark grays are compressed, the
> > near-white grays show up correct.  My Xorg.0.log shows that the TV on
> > HDMI-0 supports the RGB 4:4:4 encoding (just like the monitor does):
> >
> > 
> > I found a xrandr-command "--set "Broadcast RGB" "Full"", which can be used
> > with chips from Intel. Is there something similar for the open source ati
> > drivers?
> Not at the moment.
> Alex

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