Markus Heiser | 5377d91 | 2016-06-30 15:18:56 +0200 | [diff] [blame^] | 1 | .. -*- coding: utf-8; mode: rst -*- |
| 2 | |
| 3 | **************************** |
| 4 | Defining Colorspaces in V4L2 |
| 5 | **************************** |
| 6 | |
| 7 | In V4L2 colorspaces are defined by four values. The first is the |
| 8 | colorspace identifier (enum :ref:`v4l2_colorspace <v4l2-colorspace>`) |
| 9 | which defines the chromaticities, the default transfer function, the |
| 10 | default Y'CbCr encoding and the default quantization method. The second |
| 11 | is the transfer function identifier (enum |
| 12 | :ref:`v4l2_xfer_func <v4l2-xfer-func>`) to specify non-standard |
| 13 | transfer functions. The third is the Y'CbCr encoding identifier (enum |
| 14 | :ref:`v4l2_ycbcr_encoding <v4l2-ycbcr-encoding>`) to specify |
| 15 | non-standard Y'CbCr encodings and the fourth is the quantization |
| 16 | identifier (enum :ref:`v4l2_quantization <v4l2-quantization>`) to |
| 17 | specify non-standard quantization methods. Most of the time only the |
| 18 | colorspace field of struct :ref:`v4l2_pix_format <v4l2-pix-format>` |
| 19 | or struct :ref:`v4l2_pix_format_mplane <v4l2-pix-format-mplane>` |
| 20 | needs to be filled in. Note that the default R'G'B' quantization is full |
| 21 | range for all colorspaces except for BT.2020 which uses limited range |
| 22 | R'G'B' quantization. |
| 23 | |
| 24 | |
| 25 | .. _v4l2-colorspace: |
| 26 | |
| 27 | .. flat-table:: V4L2 Colorspaces |
| 28 | :header-rows: 1 |
| 29 | :stub-columns: 0 |
| 30 | |
| 31 | |
| 32 | - .. row 1 |
| 33 | |
| 34 | - Identifier |
| 35 | |
| 36 | - Details |
| 37 | |
| 38 | - .. row 2 |
| 39 | |
| 40 | - ``V4L2_COLORSPACE_DEFAULT`` |
| 41 | |
| 42 | - The default colorspace. This can be used by applications to let |
| 43 | the driver fill in the colorspace. |
| 44 | |
| 45 | - .. row 3 |
| 46 | |
| 47 | - ``V4L2_COLORSPACE_SMPTE170M`` |
| 48 | |
| 49 | - See :ref:`col-smpte-170m`. |
| 50 | |
| 51 | - .. row 4 |
| 52 | |
| 53 | - ``V4L2_COLORSPACE_REC709`` |
| 54 | |
| 55 | - See :ref:`col-rec709`. |
| 56 | |
| 57 | - .. row 5 |
| 58 | |
| 59 | - ``V4L2_COLORSPACE_SRGB`` |
| 60 | |
| 61 | - See :ref:`col-srgb`. |
| 62 | |
| 63 | - .. row 6 |
| 64 | |
| 65 | - ``V4L2_COLORSPACE_ADOBERGB`` |
| 66 | |
| 67 | - See :ref:`col-adobergb`. |
| 68 | |
| 69 | - .. row 7 |
| 70 | |
| 71 | - ``V4L2_COLORSPACE_BT2020`` |
| 72 | |
| 73 | - See :ref:`col-bt2020`. |
| 74 | |
| 75 | - .. row 8 |
| 76 | |
| 77 | - ``V4L2_COLORSPACE_DCI_P3`` |
| 78 | |
| 79 | - See :ref:`col-dcip3`. |
| 80 | |
| 81 | - .. row 9 |
| 82 | |
| 83 | - ``V4L2_COLORSPACE_SMPTE240M`` |
| 84 | |
| 85 | - See :ref:`col-smpte-240m`. |
| 86 | |
| 87 | - .. row 10 |
| 88 | |
| 89 | - ``V4L2_COLORSPACE_470_SYSTEM_M`` |
| 90 | |
| 91 | - See :ref:`col-sysm`. |
| 92 | |
| 93 | - .. row 11 |
| 94 | |
| 95 | - ``V4L2_COLORSPACE_470_SYSTEM_BG`` |
| 96 | |
| 97 | - See :ref:`col-sysbg`. |
| 98 | |
| 99 | - .. row 12 |
| 100 | |
| 101 | - ``V4L2_COLORSPACE_JPEG`` |
| 102 | |
| 103 | - See :ref:`col-jpeg`. |
| 104 | |
| 105 | - .. row 13 |
| 106 | |
| 107 | - ``V4L2_COLORSPACE_RAW`` |
| 108 | |
| 109 | - The raw colorspace. This is used for raw image capture where the |
| 110 | image is minimally processed and is using the internal colorspace |
| 111 | of the device. The software that processes an image using this |
| 112 | 'colorspace' will have to know the internals of the capture |
| 113 | device. |
| 114 | |
| 115 | |
| 116 | |
| 117 | .. _v4l2-xfer-func: |
| 118 | |
| 119 | .. flat-table:: V4L2 Transfer Function |
| 120 | :header-rows: 1 |
| 121 | :stub-columns: 0 |
| 122 | |
| 123 | |
| 124 | - .. row 1 |
| 125 | |
| 126 | - Identifier |
| 127 | |
| 128 | - Details |
| 129 | |
| 130 | - .. row 2 |
| 131 | |
| 132 | - ``V4L2_XFER_FUNC_DEFAULT`` |
| 133 | |
| 134 | - Use the default transfer function as defined by the colorspace. |
| 135 | |
| 136 | - .. row 3 |
| 137 | |
| 138 | - ``V4L2_XFER_FUNC_709`` |
| 139 | |
| 140 | - Use the Rec. 709 transfer function. |
| 141 | |
| 142 | - .. row 4 |
| 143 | |
| 144 | - ``V4L2_XFER_FUNC_SRGB`` |
| 145 | |
| 146 | - Use the sRGB transfer function. |
| 147 | |
| 148 | - .. row 5 |
| 149 | |
| 150 | - ``V4L2_XFER_FUNC_ADOBERGB`` |
| 151 | |
| 152 | - Use the AdobeRGB transfer function. |
| 153 | |
| 154 | - .. row 6 |
| 155 | |
| 156 | - ``V4L2_XFER_FUNC_SMPTE240M`` |
| 157 | |
| 158 | - Use the SMPTE 240M transfer function. |
| 159 | |
| 160 | - .. row 7 |
| 161 | |
| 162 | - ``V4L2_XFER_FUNC_NONE`` |
| 163 | |
| 164 | - Do not use a transfer function (i.e. use linear RGB values). |
| 165 | |
| 166 | - .. row 8 |
| 167 | |
| 168 | - ``V4L2_XFER_FUNC_DCI_P3`` |
| 169 | |
| 170 | - Use the DCI-P3 transfer function. |
| 171 | |
| 172 | - .. row 9 |
| 173 | |
| 174 | - ``V4L2_XFER_FUNC_SMPTE2084`` |
| 175 | |
| 176 | - Use the SMPTE 2084 transfer function. |
| 177 | |
| 178 | |
| 179 | |
| 180 | .. _v4l2-ycbcr-encoding: |
| 181 | |
| 182 | .. flat-table:: V4L2 Y'CbCr Encodings |
| 183 | :header-rows: 1 |
| 184 | :stub-columns: 0 |
| 185 | |
| 186 | |
| 187 | - .. row 1 |
| 188 | |
| 189 | - Identifier |
| 190 | |
| 191 | - Details |
| 192 | |
| 193 | - .. row 2 |
| 194 | |
| 195 | - ``V4L2_YCBCR_ENC_DEFAULT`` |
| 196 | |
| 197 | - Use the default Y'CbCr encoding as defined by the colorspace. |
| 198 | |
| 199 | - .. row 3 |
| 200 | |
| 201 | - ``V4L2_YCBCR_ENC_601`` |
| 202 | |
| 203 | - Use the BT.601 Y'CbCr encoding. |
| 204 | |
| 205 | - .. row 4 |
| 206 | |
| 207 | - ``V4L2_YCBCR_ENC_709`` |
| 208 | |
| 209 | - Use the Rec. 709 Y'CbCr encoding. |
| 210 | |
| 211 | - .. row 5 |
| 212 | |
| 213 | - ``V4L2_YCBCR_ENC_XV601`` |
| 214 | |
| 215 | - Use the extended gamut xvYCC BT.601 encoding. |
| 216 | |
| 217 | - .. row 6 |
| 218 | |
| 219 | - ``V4L2_YCBCR_ENC_XV709`` |
| 220 | |
| 221 | - Use the extended gamut xvYCC Rec. 709 encoding. |
| 222 | |
| 223 | - .. row 7 |
| 224 | |
| 225 | - ``V4L2_YCBCR_ENC_SYCC`` |
| 226 | |
| 227 | - Use the extended gamut sYCC encoding. |
| 228 | |
| 229 | - .. row 8 |
| 230 | |
| 231 | - ``V4L2_YCBCR_ENC_BT2020`` |
| 232 | |
| 233 | - Use the default non-constant luminance BT.2020 Y'CbCr encoding. |
| 234 | |
| 235 | - .. row 9 |
| 236 | |
| 237 | - ``V4L2_YCBCR_ENC_BT2020_CONST_LUM`` |
| 238 | |
| 239 | - Use the constant luminance BT.2020 Yc'CbcCrc encoding. |
| 240 | |
| 241 | |
| 242 | |
| 243 | .. _v4l2-quantization: |
| 244 | |
| 245 | .. flat-table:: V4L2 Quantization Methods |
| 246 | :header-rows: 1 |
| 247 | :stub-columns: 0 |
| 248 | |
| 249 | |
| 250 | - .. row 1 |
| 251 | |
| 252 | - Identifier |
| 253 | |
| 254 | - Details |
| 255 | |
| 256 | - .. row 2 |
| 257 | |
| 258 | - ``V4L2_QUANTIZATION_DEFAULT`` |
| 259 | |
| 260 | - Use the default quantization encoding as defined by the |
| 261 | colorspace. This is always full range for R'G'B' (except for the |
| 262 | BT.2020 colorspace) and usually limited range for Y'CbCr. |
| 263 | |
| 264 | - .. row 3 |
| 265 | |
| 266 | - ``V4L2_QUANTIZATION_FULL_RANGE`` |
| 267 | |
| 268 | - Use the full range quantization encoding. I.e. the range [0…1] is |
| 269 | mapped to [0…255] (with possible clipping to [1…254] to avoid the |
| 270 | 0x00 and 0xff values). Cb and Cr are mapped from [-0.5…0.5] to |
| 271 | [0…255] (with possible clipping to [1…254] to avoid the 0x00 and |
| 272 | 0xff values). |
| 273 | |
| 274 | - .. row 4 |
| 275 | |
| 276 | - ``V4L2_QUANTIZATION_LIM_RANGE`` |
| 277 | |
| 278 | - Use the limited range quantization encoding. I.e. the range [0…1] |
| 279 | is mapped to [16…235]. Cb and Cr are mapped from [-0.5…0.5] to |
| 280 | [16…240]. |
| 281 | |
| 282 | |
| 283 | |
| 284 | |
| 285 | .. ------------------------------------------------------------------------------ |
| 286 | .. This file was automatically converted from DocBook-XML with the dbxml |
| 287 | .. library (https://github.com/return42/sphkerneldoc). The origin XML comes |
| 288 | .. from the linux kernel, refer to: |
| 289 | .. |
| 290 | .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook |
| 291 | .. ------------------------------------------------------------------------------ |