Re: Guide: Display Calibration – Part I

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October 22, 2010 at 2:49 pm #1709
Aaron Ledger

    [quote=”jameson_uk”]
    The major issue with HTPC display calibration is that things are not static.
    The choice of codec and renderer can affect what is displayed.
    I have a 9400 IGP and if output is set to 16-235 for video and I play a 16-235 video then you would think that output would just be at 16-235 it does not work.   At various points the video is converted from/to 16-235 / 0-255 and what actualy happens when playing back video with the output set to 16-235 results in the renderer assuming the input is 0-255 and converting this to 16-235 (giving you washed out blacks and grey whites).  Setting the output to 0-255 means I actually get 16-235 out for a 16-235 source.

    To make matters more complicated things can be different for HD (Rec 709) and SD (Rec 601) material as well as proteted path material.   In order to get correct black levels when using TMT I need to set the output to 16-235 to get 16-235 output (even though in MPC etc I need to have output set to 0-255 to achieve the same….)

    This is all measured on a meter on a set calibrated to 16-235 from another source (stand alone bluray player)

    I am guessing you will address some of these issues in part II?
    [/quote]

    The color space issue was addressed to some degree in this guide. It is unfortunate that there are sometimes inconsitencies in how different software packages, drivers and hardware deal with video levels. Fortunately, we have test patterns to allow us to identify and correct those issues.

    It would be ideal to have separate calibrations for viewing Rec. 709 and Rec. 601, although if you have to choose one, choose the one for the type of content you watch most. Alternately, you could create different calibration picture modes on your display for each. You could also do this to deal with any inconsistencies you are finding in your hardare/software.

    Are you also using the latest version of TMT along with current Nvidia drivers? I understand that at one point, there was a problem with levels in TMT. Last I checked on a Clarkdale GPU outputting full-range RGB, I was seeing consistent levels with MPC and TMT using AVS HD 709 pluge pattern.