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| author | Hans Verkuil <hansverk@cisco.com> | 2017-07-27 12:22:29 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2017-08-08 13:09:41 +0300 |
| commit | c795e7d0900fa815bc7df72bd1db816764132935 (patch) | |
| tree | 34b2360aa662d8b5465066d88224c64a53b4a67b /Documentation/media/uapi/v4l | |
| parent | fb98531e8916c65c1db0434b343d335574431843 (diff) | |
| download | linux-c795e7d0900fa815bc7df72bd1db816764132935.tar.xz | |
media: media/doc: improve the SMPTE 2084 documentation
Make note of the different luminance ranges between HDR and SDR.
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'Documentation/media/uapi/v4l')
| -rw-r--r-- | Documentation/media/uapi/v4l/colorspaces-details.rst | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/media/uapi/v4l/colorspaces-details.rst b/Documentation/media/uapi/v4l/colorspaces-details.rst index 47d7d1915284..b5d551b9cc8f 100644 --- a/Documentation/media/uapi/v4l/colorspaces-details.rst +++ b/Documentation/media/uapi/v4l/colorspaces-details.rst @@ -793,3 +793,15 @@ Transfer function: Inverse Transfer function: L = (max(L':sup:`1/m2` - c1, 0) / (c2 - c3 * L'\ :sup:`1/m2`))\ :sup:`1/m1` + +Take care when converting between this transfer function and non-HDR transfer +functions: the linear RGB values [0…1] of HDR content map to a luminance range +of 0 to 10000 cd/m\ :sup:`2` whereas the linear RGB values of non-HDR (aka +Standard Dynamic Range or SDR) map to a luminance range of 0 to 100 cd/m\ :sup:`2`. + +To go from SDR to HDR you will have to divide L by 100 first. To go in the other +direction you will have to multiply L by 100. Of course, this clamps all +luminance values over 100 cd/m\ :sup:`2` to 100 cd/m\ :sup:`2`. + +There are better methods, see e.g. :ref:`colimg` for more in-depth information +about this. |