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February 10, 2015 / ftth

Forcing HDMI colorspace to Full on intel haswell / Arch Linux

Moving to a new i7-4771 computer (haswell), i had to connect one of my two monitors using HDMI. Unfortunately, the contrast seemed really low compared to the other (identical) display, exactly as if the brighness had been boosted and contrast lowered. A washed out, dull picture.

What happens is that the Intel GPU i915 driver falls back automatically to a limited colorspace (that is normally supported by flat TVs).

The awesome Arch wiki provided the solution, but does not give a lot of hints on where to deploy the fix.

I ended up putting the following shell script into /etc/X11/xinit/xinitrc.d/50-intel-fix.sh

if [ "$(/usr/bin/xrandr -q --prop | grep 'Broadcast RGB: Full' | wc -l)" = "0" ] ; then
/usr/bin/xrandr --output HDMI2 --set "Broadcast RGB" "Full"
fi

(don’t forget to replace “HDMI2” by your own display name, as reported by xrandr).

It’s sad to think that a 2013 released processor/GPU still has this kind of issues. Oh, and did i mention i am using the latest stable kernel/driver stack ?

Edit: another way to fix this is using a DVI-HDMI adapter on the display, it forces the GPU to use proper DVI/RGB with full colorspace depth.

images

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