The :ref:`srgb` standard defines the colorspace used by most webcams
and computer graphics. The default transfer function is
``V4L2_XFER_FUNC_SRGB``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is full range.
+``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited range.
+
+Note that the :ref:`sycc` standard specifies full range quantization,
+however all current capture hardware supported by the kernel convert
+R'G'B' to limited range Y'CbCr. So choosing full range as the default
+would break how applications interpret the quantization range.
+
The chromaticities of the primary colors and the white reference are:
Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
[-0.5…0.5]. This transform is identical to one defined in SMPTE
-170M/BT.601. The Y'CbCr quantization is full range.
+170M/BT.601. The Y'CbCr quantization is limited range.
.. _col-adobergb:
graphics that use the AdobeRGB colorspace. This is also known as the
:ref:`oprgb` standard. The default transfer function is
``V4L2_XFER_FUNC_ADOBERGB``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is full
-range. The chromaticities of the primary colors and the white reference
-are:
+``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited
+range.
+
+Note that the :ref:`oprgb` standard specifies full range quantization,
+however all current capture hardware supported by the kernel convert
+R'G'B' to limited range Y'CbCr. So choosing full range as the default
+would break how applications interpret the quantization range.
+The chromaticities of the primary colors and the white reference are:
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
[-0.5…0.5]. This transform is identical to one defined in SMPTE
-170M/BT.601. The Y'CbCr quantization is full range.
+170M/BT.601. The Y'CbCr quantization is limited range.
.. _col-bt2020: