Comments on: Fixing Media Center’s Poor Black Levels

By: Michael Healy

Michael Healy — Mon, 07 Sep 2009 13:34:37 +0000

It depends mostly on the calibration of the monitor being used and whether it has been set to 16-235 or 0-255 black levels as the default colorspace. If a monitor has specified 16 as the lowest black and 235 as the highest white then setting the colorspace to 0-255 will result in a washed out appearance.

By: Ben

Ben — Mon, 07 Sep 2009 08:13:35 +0000

Of course, this will need to be applied in a per situation basis. Not every user should employ this modification and the application will depend on the hardware being used.

How does it depend on the hardware being used? If you have the proper black levels in WMP but not in 7MC then surely its just a problem with 7MC? I have my colorspace set to YCbCr444 in ATI CCC and seem to get the proper black levels in WMP but not in 7MC.

By: IanK

IanK — Mon, 22 Jun 2009 22:31:30 +0000

Setting 0-255 in either control panel or via the registry forces a color space conversion and will introduce banding under some conditions.

Out of the box over DVI MCE does no color space conversion. Broadcast and consumer media is authored for 16-235 and by default that’s what you get unless the driver does its own thing. For optimal black levels you should leave them be and calibrate your display.

This all goes out the windows with HDMI. HDMI spec and logo/licensing requirements require all video be constrained to 16-235. As such most HDMI enabled GPUs force a 0-255 -> 16-235 conversion on output at a point way beyond the control panel or DXVA control. This ensures ALL content is within the 16-235 range. Since broadcast content is already at 16-235 this really washes things out and you need to set 0-255 via the registry or the control panel to get 16-235 back. Getting video down to 0-255 in this scenario is impossible.

Finally, some GPU vendors ignore what DXVA tells them to do. So the regkeys may not work.

By: Michael Healy

Michael Healy — Wed, 10 Jun 2009 23:59:46 +0000

That’s true, selecting the proper color format will improve color quite a bit as well. Though on nVidia cards that use DVI -> HDMI only the RGB option is selectable in the control panel.

By: Carlton

Carlton — Wed, 10 Jun 2009 22:58:23 +0000

If you’re using the HDMI on an nVidia card, selecting the proper digital color format (YCbCr444 or RGB) will dramatically improve the black level if it is improperly. Changed the image on my projector from gray to black.

Screen capture:
http://s3.carltonbale.com/hdmi_color_format.jpg

By: Michael Healy

Michael Healy — Wed, 10 Jun 2009 21:07:30 +0000

Thanks, fixed the link.

By: Jens Schaller

Jens Schaller — Wed, 10 Jun 2009 20:55:41 +0000

There is a “/” missing in the registry file URL: http://www.hack7mc.comwp-content/

Anyways, thanks for the great tip!

By: hamiltonguy

hamiltonguy — Wed, 10 Jun 2009 13:52:54 +0000

Thank you for the simple yet excellent explanation. great post!