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Commit fb98531e authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
Browse files

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: default avatarHans Verkuil <hansverk@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent 5dcd7c66

Documentation/media/uapi/v4l/colorspaces-defs.rst

+1 −1
Original line number Diff line number Diff line
@@ -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`.

Documentation/media/uapi/v4l/colorspaces-details.rst

+5 −0
Original line number Diff line number Diff line
@@ -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: