HDMI: Image on TV too dark

[Alex Deucher]

On Thu, Oct 13, 2011 at 10:37 AM, Frederik Vogelsang
<frederik.vogelsang at googlemail.com> wrote:
> 2011/10/13 Alex Deucher <alexdeucher at gmail.com>:
>> The brightness is set on the TV itself.  The only thing the driver can
>> really adjust is the gamma correction which is exposed via xrandr or
>> xgamma if you want to adjust it.
> I can turn up the brightness on the TV, but that only causes the TV's
> backlight to increase. The actual dark areas stay pretty much black. I
> did also already mess with xgamma but this does not improve the
> situation either.
>
>>  You might try connecting directly to
>> the TV as Andy suggested, or try booting with radeon.audio=0 depending
>> on how old your kernel is.
> I've tried both. Neither a direct TV HDMI connection (without the AV
> receiver) nor radeon.audio=0 fixed the issue.
>
> Another strange thing: the picture quality (also with dark areas) on
> Windows with the AMD Catalyst driver is also fine. I did not have to
> make any brightness changes for that system, it worked out of the box
> without any settings. So it has to be specific to the Linux side.
>
> Any more ideas? Can anyone tell how the default brightness level is
> set for digital outputs? Is it calculated or hard coded? What about an
> xorg.conf setting?

Other than the gamma stuff, there is no "brightness" setting in the
display hardware.

Alex