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Diffstat (limited to 'Documentation/media/uapi/v4l/pixfmt-007.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/pixfmt-007.rst | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/Documentation/media/uapi/v4l/pixfmt-007.rst b/Documentation/media/uapi/v4l/pixfmt-007.rst index 95a23a28c595..0c30ee2577d3 100644 --- a/Documentation/media/uapi/v4l/pixfmt-007.rst +++ b/Documentation/media/uapi/v4l/pixfmt-007.rst @@ -174,7 +174,7 @@ this colorspace: The xvYCC 709 encoding (``V4L2_YCBCR_ENC_XV709``, :ref:`xvycc`) is similar to the Rec. 709 encoding, but it allows for R', G' and B' values that are outside the range [0…1]. The resulting Y', Cb and Cr values are -scaled and offset: +scaled and offset according to the limited range formula: .. math:: @@ -187,7 +187,7 @@ scaled and offset: The xvYCC 601 encoding (``V4L2_YCBCR_ENC_XV601``, :ref:`xvycc`) is similar to the BT.601 encoding, but it allows for R', G' and B' values that are outside the range [0…1]. The resulting Y', Cb and Cr values are -scaled and offset: +scaled and offset according to the limited range formula: .. math:: @@ -198,9 +198,14 @@ scaled and offset: Cr = \frac{224}{256} * (0.5R' - 0.4187G' - 0.0813B') Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range -[-0.5…0.5]. The non-standard xvYCC 709 or xvYCC 601 encodings can be +[-0.5…0.5] and quantized without further scaling or offsets. +The non-standard xvYCC 709 or xvYCC 601 encodings can be used by selecting ``V4L2_YCBCR_ENC_XV709`` or ``V4L2_YCBCR_ENC_XV601``. -The xvYCC encodings always use full range quantization. +As seen by the xvYCC formulas these encodings always use limited range quantization, +there is no full range variant. The whole point of these extended gamut encodings +is that values outside the limited range are still valid, although they +map to R', G' and B' values outside the [0…1] range and are therefore outside +the Rec. 709 colorspace gamut. .. _col-srgb: |