From 61f5a80f1070202a5b993591770653184328f629 Mon Sep 17 00:00:00 2001 From: Niklas Haas Date: Wed, 14 Jan 2015 00:45:31 +0100 Subject: vo_opengl: get rid of approx-gamma and make it the default as per BT.1886 After finding out more about how video mastering is done in the real world it dawned upon me why the "hack" we figured out in #534 looks so much better. Since mastering studios have historically been using only CRTs, the practice adopted for backwards compatibility was to simulate CRT responses even on modern digital monitors, a practice so ubiquitous that the ITU-R formalized it in R-Rec BT.1886 to be precisely gamma 2.40. As such, we finally have enough proof to get rid of the option altogether and just always do that. The value 1.961 is a rounded version of my experimentally obtained approximation of the BT.709 curve, which resulted in a value of around 1.9610336. This is the closest average match to the source brightness while preserving the nonlinear response of the BT.1886 ideal monitor. For playback in dark environments, it's expected that the gamma shift should be reproduced by a user controlled setting, up to a maximum of 1.224 (2.4/1.961) for a pitch black environment. More information: https://developer.apple.com/library/mac/technotes/tn2257/_index.html --- DOCS/man/vo.rst | 10 ---------- 1 file changed, 10 deletions(-) (limited to 'DOCS') diff --git a/DOCS/man/vo.rst b/DOCS/man/vo.rst index 92b88dc523..bbca84ecdb 100644 --- a/DOCS/man/vo.rst +++ b/DOCS/man/vo.rst @@ -568,16 +568,6 @@ Available video output drivers are: 3 absolute colorimetric - ``approx-gamma`` - Approximate the actual gamma function as a pure power curve of - 1.95. A number of video editing programs and studios apparently use this - for mastering instead of the true curve. Most notably, anything in the - Apple ecosystem uses this approximation - including all programs - compatible with it. It's a sound idea to try enabling this flag first - when watching videos and shows to see if things look better that way. - - This only affects the output when using either ``icc-profile`` or ``srgb``. - ``3dlut-size=xx`` Size of the 3D LUT generated from the ICC profile in each dimension. Default is 128x256x64. -- cgit v1.2.3