HDMI: Image on TV too dark

[Frederik Vogelsang]

Hi,

I am experiencing a strange issue: I have connected my TV to my
computer via HDMI (AV receiver in between them) and whenever I play a
movie on my PC the picture looses it's details in dark scenes (dark
areas become just black). First I tried to change the settings on my
TV (brightness, contrast, ...) but this did not really make a
significant change.

I finally tracked down the problem to the brightness setting on the
computer. When I change the brightness with

$> xcalib -b 8.0 -a

the picture on the TV looks fine. Is this normal? I thought since I am
using all digital connections I would not have to deal with things
such as brightness any more. Could there be anything wrong on the
driver side (default brightness value wrong)? Is there any way to
change the brightness level without xcalib (maybe xorg.conf)?


GFX: Radeon HD 3870
TV: Panasonic TX-L37V10E
SW: Linux 3.1-git, mesa-git, xf86-video-ati-git, libdrm-git, KMS


Regards,
 Frederik