From fb98531e8916c65c1db0434b343d335574431843 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Thu, 27 Jul 2017 05:09:10 -0400 Subject: [PATCH] media: media/doc: improve bt.2020 documentation Add a note stating that bt.2020 is often used in combination with the smpte 2084 transfer function. Also use the right references to the documentation of that transfer function. Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/media/uapi/v4l/colorspaces-defs.rst | 2 +- Documentation/media/uapi/v4l/colorspaces-details.rst | 5 +++++ 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/Documentation/media/uapi/v4l/colorspaces-defs.rst b/Documentation/media/uapi/v4l/colorspaces-defs.rst index 7ae7dcf..e67ed1e 100644 --- a/Documentation/media/uapi/v4l/colorspaces-defs.rst +++ b/Documentation/media/uapi/v4l/colorspaces-defs.rst @@ -97,7 +97,7 @@ whole range, 0-255, dividing the angular value by 1.41. The enum * - ``V4L2_XFER_FUNC_DCI_P3`` - Use the DCI-P3 transfer function. * - ``V4L2_XFER_FUNC_SMPTE2084`` - - Use the SMPTE 2084 transfer function. + - Use the SMPTE 2084 transfer function. See :ref:`xf-smpte-2084`. diff --git a/Documentation/media/uapi/v4l/colorspaces-details.rst b/Documentation/media/uapi/v4l/colorspaces-details.rst index 128b2ac..47d7d19 100644 --- a/Documentation/media/uapi/v4l/colorspaces-details.rst +++ b/Documentation/media/uapi/v4l/colorspaces-details.rst @@ -418,6 +418,11 @@ Inverse Transfer function: L = \left( \frac{L' + 0.099}{1.099}\right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.081 +Please note that while Rec. 709 is defined as the default transfer function +by the :ref:`itu2020` standard, in practice this colorspace is often used +with the :ref:`xf-smpte-2084`. In particular Ultra HD Blu-ray discs use +this combination. + The luminance (Y') and color difference (Cb and Cr) are obtained with the following ``V4L2_YCBCR_ENC_BT2020`` encoding: -- 2.7.4