요약·해설과 원문, 전문 번역을 서로 분리했습니다. API 이름, symbol, source path는 원문 표기를 사용합니다.
1. 요약·해설
원문의 핵심 논리와 kernel programming 관점의 보충 설명입니다. 아래의 전문 번역과는 별도로 작성했습니다.
2. 영어 원문 전체
번역 기준이 된 Linux v6.18.37 원문입니다. 줄 번호는 이 버전의 파일 좌표입니다.
원문 전체 펼치기
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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. _colorimetry-controls:
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*****************************
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Colorimetry Control Reference
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*****************************
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The Colorimetry class includes controls for High Dynamic Range
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imaging for representing colors in digital images and video. The
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controls should be used for video and image encoding and decoding
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as well as in HDMI receivers and transmitters.
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Colorimetry Control IDs
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-----------------------
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.. _colorimetry-control-id:
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``V4L2_CID_COLORIMETRY_CLASS (class)``
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The Colorimetry class descriptor. Calling
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:ref:`VIDIOC_QUERYCTRL` for this control will
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return a description of this control class.
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``V4L2_CID_COLORIMETRY_HDR10_CLL_INFO (struct)``
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The Content Light Level defines upper bounds for the nominal target
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brightness light level of the pictures.
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.. c:type:: v4l2_ctrl_hdr10_cll_info
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.. cssclass:: longtable
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.. flat-table:: struct v4l2_ctrl_hdr10_cll_info
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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* - __u16
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- ``max_content_light_level``
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- The upper bound for the maximum light level among all individual
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samples for the pictures of a video sequence, cd/m\ :sup:`2`.
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When equal to 0 no such upper bound is present.
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* - __u16
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- ``max_pic_average_light_level``
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- The upper bound for the maximum average light level among the
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samples for any individual picture of a video sequence,
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cd/m\ :sup:`2`. When equal to 0 no such upper bound is present.
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``V4L2_CID_COLORIMETRY_HDR10_MASTERING_DISPLAY (struct)``
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The mastering display defines the color volume (the color primaries,
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white point and luminance range) of a display considered to be the
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mastering display for the current video content.
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.. c:type:: v4l2_ctrl_hdr10_mastering_display
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.. cssclass:: longtable
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.. flat-table:: struct v4l2_ctrl_hdr10_mastering_display
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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* - __u16
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- ``display_primaries_x[3]``
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- Specifies the normalized x chromaticity coordinate of the color
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primary component c of the mastering display in increments of 0.00002.
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For describing the mastering display that uses Red, Green and Blue
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color primaries, index value c equal to 0 corresponds to the Green
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primary, c equal to 1 corresponds to Blue primary and c equal to 2
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corresponds to the Red color primary.
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* - __u16
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- ``display_primaries_y[3]``
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- Specifies the normalized y chromaticity coordinate of the color
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primary component c of the mastering display in increments of 0.00002.
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For describing the mastering display that uses Red, Green and Blue
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color primaries, index value c equal to 0 corresponds to the Green
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primary, c equal to 1 corresponds to Blue primary and c equal to 2
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corresponds to Red color primary.
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* - __u16
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- ``white_point_x``
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- Specifies the normalized x chromaticity coordinate of the white
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point of the mastering display in increments of 0.00002.
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* - __u16
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- ``white_point_y``
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- Specifies the normalized y chromaticity coordinate of the white
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point of the mastering display in increments of 0.00002.
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* - __u32
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- ``max_luminance``
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- Specifies the nominal maximum display luminance of the mastering
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display in units of 0.0001 cd/m\ :sup:`2`.
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* - __u32
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- ``min_luminance``
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- specifies the nominal minimum display luminance of the mastering
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display in units of 0.0001 cd/m\ :sup:`2`.
3. 한국어 전문 번역
영어 원문의 문단 순서와 의미를 유지한 전체 번역입니다. 코드, 함수명, symbol과 URL은 원문 표기를 유지합니다.
Colorimetry와 HDR10 metadata
1-23Colorimetry 제어 클래스는 디지털 image와 video에서 색을 표현하기 위한 High Dynamic Range metadata를 제공합니다. Video·image encoder와 decoder뿐 아니라 HDMI receiver와 transmitter도 이 제어를 사용할 수 있습니다.
`V4L2_CID_COLORIMETRY_CLASS`는 Colorimetry class descriptor입니다. 이 control에 `VIDIOC_QUERYCTRL`을 호출하면 class 설명을 얻습니다.
Mastering 단계에서 색 원색·white point·luminance 기록→Content light-level 상한 계산→Encoder가 HDR10 metadata control 설정→HDMI transmitter가 metadata 전송→Receiver·decoder·display가 tone mapping에 활용
콘텐츠가 밝기와 mastering display 정보를 signal chain 전체에 전달합니다.
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. _colorimetry-controls:
*****************************
Colorimetry Control Reference
*****************************
The Colorimetry class includes controls for High Dynamic Range
imaging for representing colors in digital images and video. The
controls should be used for video and image encoding and decoding
as well as in HDMI receivers and transmitters.
Colorimetry Control IDs
-----------------------
.. _colorimetry-control-id:
``V4L2_CID_COLORIMETRY_CLASS (class)``
The Colorimetry class descriptor. Calling
:ref:`VIDIOC_QUERYCTRL` for this control will
return a description of this control class.
HDR10 Content Light Level
24-47`V4L2_CID_COLORIMETRY_HDR10_CLL_INFO`는 영상 sequence의 nominal target brightness 상한을 `v4l2_ctrl_hdr10_cll_info` 구조체로 전달합니다.
필드의미
`max_content_light_level`Sequence의 모든 개별 sample 가운데 최대 light level의 상한입니다. 단위는 cd/m²입니다.
`max_pic_average_light_level`Sequence의 각 picture별 평균 light level 가운데 최대값의 상한입니다. 단위는 cd/m²입니다.
두 값 모두 cd/m² 단위이며 0은 해당 상한이 제공되지 않았음을 뜻합니다.
CLL metadata는 실제 display peak luminance를 강제하지 않고 콘텐츠가 의도한 밝기 범위를 알려 줍니다. Display 또는 tone mapper는 자체 능력과 이 상한을 함께 사용합니다.
``V4L2_CID_COLORIMETRY_HDR10_CLL_INFO (struct)``
The Content Light Level defines upper bounds for the nominal target
brightness light level of the pictures.
.. c:type:: v4l2_ctrl_hdr10_cll_info
.. cssclass:: longtable
.. flat-table:: struct v4l2_ctrl_hdr10_cll_info
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
* - __u16
- ``max_content_light_level``
- The upper bound for the maximum light level among all individual
samples for the pictures of a video sequence, cd/m\ :sup:`2`.
When equal to 0 no such upper bound is present.
* - __u16
- ``max_pic_average_light_level``
- The upper bound for the maximum average light level among the
samples for any individual picture of a video sequence,
cd/m\ :sup:`2`. When equal to 0 no such upper bound is present.
HDR10 mastering display 색 부피
48-93`V4L2_CID_COLORIMETRY_HDR10_MASTERING_DISPLAY`는 현재 콘텐츠를 제작할 때 기준으로 삼은 mastering display의 color volume을 `v4l2_ctrl_hdr10_mastering_display`로 전달합니다. Color primaries, white point와 luminance range가 포함됩니다.
필드의미
`display_primaries_x[3]`원색의 normalized x chromaticity 좌표입니다. 단위 증분은 0.00002이며 index 0=Green, 1=Blue, 2=Red입니다.
`display_primaries_y[3]`원색의 normalized y chromaticity 좌표입니다. 단위 증분과 G/B/R index 순서는 x 배열과 같습니다.
`white_point_x`Mastering display white point의 normalized x 좌표이며 0.00002 단위입니다.
`white_point_y`Mastering display white point의 normalized y 좌표이며 0.00002 단위입니다.
`max_luminance`Mastering display의 nominal 최대 luminance이며 0.0001 cd/m² 단위입니다.
`min_luminance`Mastering display의 nominal 최소 luminance이며 0.0001 cd/m² 단위입니다.
좌표와 luminance의 정수 배율을 그대로 보존합니다.
RGB 원색 배열의 순서가 일반적인 R/G/B가 아니라 G/B/R이므로 index를 바꾸어 전달하면 색 부피가 잘못 해석됩니다. Integer 값을 실제 좌표와 휘도로 바꿀 때는 명시된 증분을 곱합니다.
``V4L2_CID_COLORIMETRY_HDR10_MASTERING_DISPLAY (struct)``
The mastering display defines the color volume (the color primaries,
white point and luminance range) of a display considered to be the
mastering display for the current video content.
.. c:type:: v4l2_ctrl_hdr10_mastering_display
.. cssclass:: longtable
.. flat-table:: struct v4l2_ctrl_hdr10_mastering_display
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
* - __u16
- ``display_primaries_x[3]``
- Specifies the normalized x chromaticity coordinate of the color
primary component c of the mastering display in increments of 0.00002.
For describing the mastering display that uses Red, Green and Blue
color primaries, index value c equal to 0 corresponds to the Green
primary, c equal to 1 corresponds to Blue primary and c equal to 2
corresponds to the Red color primary.
* - __u16
- ``display_primaries_y[3]``
- Specifies the normalized y chromaticity coordinate of the color
primary component c of the mastering display in increments of 0.00002.
For describing the mastering display that uses Red, Green and Blue
color primaries, index value c equal to 0 corresponds to the Green
primary, c equal to 1 corresponds to Blue primary and c equal to 2
corresponds to Red color primary.
* - __u16
- ``white_point_x``
- Specifies the normalized x chromaticity coordinate of the white
point of the mastering display in increments of 0.00002.
* - __u16
- ``white_point_y``
- Specifies the normalized y chromaticity coordinate of the white
point of the mastering display in increments of 0.00002.
* - __u32
- ``max_luminance``
- Specifies the nominal maximum display luminance of the mastering
display in units of 0.0001 cd/m\ :sup:`2`.
* - __u32
- ``min_luminance``
- specifies the nominal minimum display luminance of the mastering
display in units of 0.0001 cd/m\ :sup:`2`.
요약·해설
ext-ctrls-colorimetry.rst:1-93HDR10 metadata는 콘텐츠의 최대 밝기와 mastering display의 원색·white point·luminance 범위를 전달합니다. 0이 '상한 없음'인 CLL 값과 chromaticity·luminance 정수 배율, G/B/R 배열 순서를 정확히 지켜야 합니다.