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/* Copyright (c) the JPEG XL Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style
* license that can be found in the LICENSE file.
*/
/** @addtogroup libjxl_color
* @{
* @file color_encoding.h
* @brief Color Encoding definitions used by JPEG XL.
* All CIE units are for the standard 1931 2 degree observer.
*/
#ifndef JXL_COLOR_ENCODING_H_
#define JXL_COLOR_ENCODING_H_
#include <stdint.h>
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
/** Color space of the image data. */
typedef enum {
/** Tristimulus RGB */
JXL_COLOR_SPACE_RGB,
/** Luminance based, the primaries in @ref JxlColorEncoding must be ignored.
* This value implies that num_color_channels in @ref JxlBasicInfo is 1, any
* other value implies num_color_channels is 3. */
JXL_COLOR_SPACE_GRAY,
/** XYB (opsin) color space */
JXL_COLOR_SPACE_XYB,
/** None of the other table entries describe the color space appropriately */
JXL_COLOR_SPACE_UNKNOWN,
} JxlColorSpace;
/** Built-in whitepoints for color encoding. When decoding, the numerical xy
* whitepoint value can be read from the @ref JxlColorEncoding white_point field
* regardless of the enum value. When encoding, enum values except
* ::JXL_WHITE_POINT_CUSTOM override the numerical fields. Some enum values
* match a subset of CICP (Rec. ITU-T H.273 | ISO/IEC 23091-2:2019(E)), however
* the white point and RGB primaries are separate enums here.
*/
typedef enum {
/** CIE Standard Illuminant D65: 0.3127, 0.3290 */
JXL_WHITE_POINT_D65 = 1,
/** White point must be read from the @ref JxlColorEncoding white_point field,
* or as ICC profile. This enum value is not an exact match of the
* corresponding CICP value. */
JXL_WHITE_POINT_CUSTOM = 2,
/** CIE Standard Illuminant E (equal-energy): 1/3, 1/3 */
JXL_WHITE_POINT_E = 10,
/** DCI-P3 from SMPTE RP 431-2: 0.314, 0.351 */
JXL_WHITE_POINT_DCI = 11,
} JxlWhitePoint;
/** Built-in primaries for color encoding. When decoding, the primaries can be
* read from the @ref JxlColorEncoding primaries_red_xy, primaries_green_xy and
* primaries_blue_xy fields regardless of the enum value. When encoding, the
* enum values except ::JXL_PRIMARIES_CUSTOM override the numerical fields.
* Some enum values match a subset of CICP (Rec. ITU-T H.273 | ISO/IEC
* 23091-2:2019(E)), however the white point and RGB primaries are separate
* enums here.
*/
typedef enum {
/** The CIE xy values of the red, green and blue primaries are: 0.639998686,
0.330010138; 0.300003784, 0.600003357; 0.150002046, 0.059997204 */
JXL_PRIMARIES_SRGB = 1,
/** Primaries must be read from the @ref JxlColorEncoding primaries_red_xy,
* primaries_green_xy and primaries_blue_xy fields, or as ICC profile. This
* enum value is not an exact match of the corresponding CICP value. */
JXL_PRIMARIES_CUSTOM = 2,
/** As specified in Rec. ITU-R BT.2100-1 */
JXL_PRIMARIES_2100 = 9,
/** As specified in SMPTE RP 431-2 */
JXL_PRIMARIES_P3 = 11,
} JxlPrimaries;
/** Built-in transfer functions for color encoding. Enum values match a subset
* of CICP (Rec. ITU-T H.273 | ISO/IEC 23091-2:2019(E)) unless specified
* otherwise. */
typedef enum {
/** As specified in SMPTE RP 431-2 */
JXL_TRANSFER_FUNCTION_709 = 1,
/** None of the other table entries describe the transfer function. */
JXL_TRANSFER_FUNCTION_UNKNOWN = 2,
/** The gamma exponent is 1 */
JXL_TRANSFER_FUNCTION_LINEAR = 8,
/** As specified in IEC 61966-2-1 sRGB */
JXL_TRANSFER_FUNCTION_SRGB = 13,
/** As specified in SMPTE ST 2084 */
JXL_TRANSFER_FUNCTION_PQ = 16,
/** As specified in SMPTE ST 428-1 */
JXL_TRANSFER_FUNCTION_DCI = 17,
/** As specified in Rec. ITU-R BT.2100-1 (HLG) */
JXL_TRANSFER_FUNCTION_HLG = 18,
/** Transfer function follows power law given by the gamma value in @ref
JxlColorEncoding. Not a CICP value. */
JXL_TRANSFER_FUNCTION_GAMMA = 65535,
} JxlTransferFunction;
/** Renderig intent for color encoding, as specified in ISO 15076-1:2010 */
typedef enum {
/** vendor-specific */
JXL_RENDERING_INTENT_PERCEPTUAL = 0,
/** media-relative */
JXL_RENDERING_INTENT_RELATIVE,
/** vendor-specific */
JXL_RENDERING_INTENT_SATURATION,
/** ICC-absolute */
JXL_RENDERING_INTENT_ABSOLUTE,
} JxlRenderingIntent;
/** Color encoding of the image as structured information.
*/
typedef struct {
/** Color space of the image data.
*/
JxlColorSpace color_space;
/** Built-in white point. If this value is ::JXL_WHITE_POINT_CUSTOM, must
* use the numerical whitepoint values from white_point_xy.
*/
JxlWhitePoint white_point;
/** Numerical whitepoint values in CIE xy space. */
double white_point_xy[2];
/** Built-in RGB primaries. If this value is ::JXL_PRIMARIES_CUSTOM, must
* use the numerical primaries values below. This field and the custom values
* below are unused and must be ignored if the color space is
* ::JXL_COLOR_SPACE_GRAY or ::JXL_COLOR_SPACE_XYB.
*/
JxlPrimaries primaries;
/** Numerical red primary values in CIE xy space. */
double primaries_red_xy[2];
/** Numerical green primary values in CIE xy space. */
double primaries_green_xy[2];
/** Numerical blue primary values in CIE xy space. */
double primaries_blue_xy[2];
/** Transfer function if have_gamma is 0 */
JxlTransferFunction transfer_function;
/** Gamma value used when transfer_function is @ref
* JXL_TRANSFER_FUNCTION_GAMMA
*/
double gamma;
/** Rendering intent defined for the color profile. */
JxlRenderingIntent rendering_intent;
} JxlColorEncoding;
#if defined(__cplusplus) || defined(c_plusplus)
}
#endif
#endif /* JXL_COLOR_ENCODING_H_ */
/** @}*/
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