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| -rw-r--r-- | Documentation/DocBook/media/v4l/pixfmt.xml | 41 |
1 files changed, 17 insertions, 24 deletions
diff --git a/Documentation/DocBook/media/v4l/pixfmt.xml b/Documentation/DocBook/media/v4l/pixfmt.xml index 5e0352c50324..13540fad3b2f 100644 --- a/Documentation/DocBook/media/v4l/pixfmt.xml +++ b/Documentation/DocBook/media/v4l/pixfmt.xml @@ -666,8 +666,7 @@ as the SMPTE C set, so this colorspace is sometimes called SMPTE C as well.</par <variablelist> <varlistentry> <term>The transfer function defined for SMPTE 170M is the same as the -one defined in Rec. 709. Normally L is in the range [0…1], but for the extended -gamut xvYCC encoding values outside that range are allowed.</term> +one defined in Rec. 709.</term> <listitem> <para>L' = -1.099(-L)<superscript>0.45</superscript> + 0.099 for L ≤ -0.018</para> <para>L' = 4.5L for -0.018 < L < 0.018</para> @@ -702,25 +701,6 @@ defined in the <xref linkend="itu601" /> standard and this colorspace is sometim though BT.601 does not mention any color primaries.</para> <para>The default quantization is limited range, but full range is possible although rarely seen.</para> - <para>The <constant>V4L2_YCBCR_ENC_601</constant> encoding as described above is the -default for this colorspace, but it can be overridden with <constant>V4L2_YCBCR_ENC_709</constant>, -in which case the Rec. 709 Y'CbCr encoding is used.</para> - <variablelist> - <varlistentry> - <term>The xvYCC 601 encoding (<constant>V4L2_YCBCR_ENC_XV601</constant>, <xref linkend="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:</term> - <listitem> - <para>Y' = (219 / 255) * (0.299R' + 0.587G' + 0.114B') + (16 / 255)</para> - <para>Cb = (224 / 255) * (-0.169R' - 0.331G' + 0.5B')</para> - <para>Cr = (224 / 255) * (0.5R' - 0.419G' - 0.081B')</para> - </listitem> - </varlistentry> - </variablelist> - <para>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 encoding can also be used by selecting -<constant>V4L2_YCBCR_ENC_XV709</constant>. The xvYCC encodings always use full range -quantization.</para> </section> <section> @@ -803,6 +783,7 @@ rarely seen.</para> <para>The <constant>V4L2_YCBCR_ENC_709</constant> encoding described above is the default for this colorspace, but it can be overridden with <constant>V4L2_YCBCR_ENC_601</constant>, in which case the BT.601 Y'CbCr encoding is used.</para> + <para>Two additional extended gamut Y'CbCr encodings are also possible with this colorspace:</para> <variablelist> <varlistentry> <term>The xvYCC 709 encoding (<constant>V4L2_YCBCR_ENC_XV709</constant>, <xref linkend="xvycc" />) @@ -815,10 +796,22 @@ is similar to the Rec. 709 encoding, but it allows for R', G' and B' values that </listitem> </varlistentry> </variablelist> + <variablelist> + <varlistentry> + <term>The xvYCC 601 encoding (<constant>V4L2_YCBCR_ENC_XV601</constant>, <xref linkend="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:</term> + <listitem> + <para>Y' = (219 / 255) * (0.299R' + 0.587G' + 0.114B') + (16 / 255)</para> + <para>Cb = (224 / 255) * (-0.169R' - 0.331G' + 0.5B')</para> + <para>Cr = (224 / 255) * (0.5R' - 0.419G' - 0.081B')</para> + </listitem> + </varlistentry> + </variablelist> <para>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 601 encoding can also be used by -selecting <constant>V4L2_YCBCR_ENC_XV601</constant>. The xvYCC encodings always use full -range quantization.</para> +to the range [-0.5…0.5]. The non-standard xvYCC 709 or xvYCC 601 encodings can be used by +selecting <constant>V4L2_YCBCR_ENC_XV709</constant> or <constant>V4L2_YCBCR_ENC_XV601</constant>. +The xvYCC encodings always use full range quantization.</para> </section> <section> |