| /* |
| * Copyright 2018 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #pragma once |
| |
| // skcms_public.h contains the entire public API for skcms. |
| |
| #ifndef SKCMS_API |
| #define SKCMS_API |
| #endif |
| |
| #include <stdbool.h> |
| #include <stddef.h> |
| #include <stdint.h> |
| #include <string.h> |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| // A row-major 3x3 matrix (ie vals[row][col]) |
| typedef struct skcms_Matrix3x3 { |
| float vals[3][3]; |
| } skcms_Matrix3x3; |
| |
| // It is _not_ safe to alias the pointers to invert in-place. |
| SKCMS_API bool skcms_Matrix3x3_invert(const skcms_Matrix3x3*, skcms_Matrix3x3*); |
| SKCMS_API skcms_Matrix3x3 skcms_Matrix3x3_concat(const skcms_Matrix3x3*, const skcms_Matrix3x3*); |
| |
| // A row-major 3x4 matrix (ie vals[row][col]) |
| typedef struct skcms_Matrix3x4 { |
| float vals[3][4]; |
| } skcms_Matrix3x4; |
| |
| // A transfer function mapping encoded values to linear values, |
| // represented by this 7-parameter piecewise function: |
| // |
| // linear = sign(encoded) * (c*|encoded| + f) , 0 <= |encoded| < d |
| // = sign(encoded) * ((a*|encoded| + b)^g + e), d <= |encoded| |
| // |
| // (A simple gamma transfer function sets g to gamma and a to 1.) |
| typedef struct skcms_TransferFunction { |
| float g, a,b,c,d,e,f; |
| } skcms_TransferFunction; |
| |
| SKCMS_API float skcms_TransferFunction_eval (const skcms_TransferFunction*, float); |
| SKCMS_API bool skcms_TransferFunction_invert(const skcms_TransferFunction*, |
| skcms_TransferFunction*); |
| |
| typedef enum skcms_TFType { |
| skcms_TFType_Invalid, |
| skcms_TFType_sRGBish, |
| skcms_TFType_PQish, |
| skcms_TFType_HLGish, |
| skcms_TFType_HLGinvish, |
| } skcms_TFType; |
| |
| // Identify which kind of transfer function is encoded in an skcms_TransferFunction |
| SKCMS_API skcms_TFType skcms_TransferFunction_getType(const skcms_TransferFunction*); |
| |
| // We can jam a couple alternate transfer function forms into skcms_TransferFunction, |
| // including those matching the general forms of the SMPTE ST 2084 PQ function or HLG. |
| // |
| // PQish: |
| // max(A + B|encoded|^C, 0) |
| // linear = sign(encoded) * (------------------------) ^ F |
| // D + E|encoded|^C |
| SKCMS_API bool skcms_TransferFunction_makePQish(skcms_TransferFunction*, |
| float A, float B, float C, |
| float D, float E, float F); |
| // HLGish: |
| // { K * sign(encoded) * ( (R|encoded|)^G ) when 0 <= |encoded| <= 1/R |
| // linear = { K * sign(encoded) * ( e^(a(|encoded|-c)) + b ) when 1/R < |encoded| |
| SKCMS_API bool skcms_TransferFunction_makeScaledHLGish(skcms_TransferFunction*, |
| float K, float R, float G, |
| float a, float b, float c); |
| |
| // Compatibility shim with K=1 for old callers. |
| static inline bool skcms_TransferFunction_makeHLGish(skcms_TransferFunction* fn, |
| float R, float G, |
| float a, float b, float c) { |
| return skcms_TransferFunction_makeScaledHLGish(fn, 1.0f, R,G, a,b,c); |
| } |
| |
| // PQ mapping encoded [0,1] to linear [0,1]. |
| static inline bool skcms_TransferFunction_makePQ(skcms_TransferFunction* tf) { |
| return skcms_TransferFunction_makePQish(tf, -107/128.0f, 1.0f, 32/2523.0f |
| , 2413/128.0f, -2392/128.0f, 8192/1305.0f); |
| } |
| // HLG mapping encoded [0,1] to linear [0,12]. |
| static inline bool skcms_TransferFunction_makeHLG(skcms_TransferFunction* tf) { |
| return skcms_TransferFunction_makeHLGish(tf, 2.0f, 2.0f |
| , 1/0.17883277f, 0.28466892f, 0.55991073f); |
| } |
| |
| // Is this an ordinary sRGB-ish transfer function, or one of the HDR forms we support? |
| SKCMS_API bool skcms_TransferFunction_isSRGBish(const skcms_TransferFunction*); |
| SKCMS_API bool skcms_TransferFunction_isPQish (const skcms_TransferFunction*); |
| SKCMS_API bool skcms_TransferFunction_isHLGish (const skcms_TransferFunction*); |
| |
| // Unified representation of 'curv' or 'para' tag data, or a 1D table from 'mft1' or 'mft2' |
| typedef union skcms_Curve { |
| struct { |
| uint32_t alias_of_table_entries; |
| skcms_TransferFunction parametric; |
| }; |
| struct { |
| uint32_t table_entries; |
| const uint8_t* table_8; |
| const uint8_t* table_16; |
| }; |
| } skcms_Curve; |
| |
| // Complex transforms between device space (A) and profile connection space (B): |
| // A2B: device -> [ "A" curves -> CLUT ] -> [ "M" curves -> matrix ] -> "B" curves -> PCS |
| // B2A: device <- [ "A" curves <- CLUT ] <- [ "M" curves <- matrix ] <- "B" curves <- PCS |
| |
| typedef struct skcms_A2B { |
| // Optional: N 1D "A" curves, followed by an N-dimensional CLUT. |
| // If input_channels == 0, these curves and CLUT are skipped, |
| // Otherwise, input_channels must be in [1, 4]. |
| uint32_t input_channels; |
| skcms_Curve input_curves[4]; |
| uint8_t grid_points[4]; |
| const uint8_t* grid_8; |
| const uint8_t* grid_16; |
| |
| // Optional: 3 1D "M" curves, followed by a color matrix. |
| // If matrix_channels == 0, these curves and matrix are skipped, |
| // Otherwise, matrix_channels must be 3. |
| uint32_t matrix_channels; |
| skcms_Curve matrix_curves[3]; |
| skcms_Matrix3x4 matrix; |
| |
| // Required: 3 1D "B" curves. Always present, and output_channels must be 3. |
| uint32_t output_channels; |
| skcms_Curve output_curves[3]; |
| } skcms_A2B; |
| |
| typedef struct skcms_B2A { |
| // Required: 3 1D "B" curves. Always present, and input_channels must be 3. |
| uint32_t input_channels; |
| skcms_Curve input_curves[3]; |
| |
| // Optional: a color matrix, followed by 3 1D "M" curves. |
| // If matrix_channels == 0, this matrix and these curves are skipped, |
| // Otherwise, matrix_channels must be 3. |
| uint32_t matrix_channels; |
| skcms_Matrix3x4 matrix; |
| skcms_Curve matrix_curves[3]; |
| |
| // Optional: an N-dimensional CLUT, followed by N 1D "A" curves. |
| // If output_channels == 0, this CLUT and these curves are skipped, |
| // Otherwise, output_channels must be in [1, 4]. |
| uint32_t output_channels; |
| uint8_t grid_points[4]; |
| const uint8_t* grid_8; |
| const uint8_t* grid_16; |
| skcms_Curve output_curves[4]; |
| } skcms_B2A; |
| |
| typedef struct skcms_CICP { |
| uint8_t color_primaries; |
| uint8_t transfer_characteristics; |
| uint8_t matrix_coefficients; |
| uint8_t video_full_range_flag; |
| } skcms_CICP; |
| |
| typedef struct skcms_ICCProfile { |
| const uint8_t* buffer; |
| |
| uint32_t size; |
| uint32_t data_color_space; |
| uint32_t pcs; |
| uint32_t tag_count; |
| |
| // skcms_Parse() will set commonly-used fields for you when possible: |
| |
| // If we can parse red, green and blue transfer curves from the profile, |
| // trc will be set to those three curves, and has_trc will be true. |
| bool has_trc; |
| skcms_Curve trc[3]; |
| |
| // If this profile's gamut can be represented by a 3x3 transform to XYZD50, |
| // skcms_Parse() sets toXYZD50 to that transform and has_toXYZD50 to true. |
| bool has_toXYZD50; |
| skcms_Matrix3x3 toXYZD50; |
| |
| // If the profile has a valid A2B0 or A2B1 tag, skcms_Parse() sets A2B to |
| // that data, and has_A2B to true. skcms_ParseWithA2BPriority() does the |
| // same following any user-provided prioritization of A2B0, A2B1, or A2B2. |
| bool has_A2B; |
| skcms_A2B A2B; |
| |
| // If the profile has a valid B2A0 or B2A1 tag, skcms_Parse() sets B2A to |
| // that data, and has_B2A to true. skcms_ParseWithA2BPriority() does the |
| // same following any user-provided prioritization of B2A0, B2A1, or B2A2. |
| bool has_B2A; |
| skcms_B2A B2A; |
| |
| // If the profile has a valid CICP tag, skcms_Parse() sets CICP to that data, |
| // and has_CICP to true. |
| bool has_CICP; |
| skcms_CICP CICP; |
| } skcms_ICCProfile; |
| |
| // The sRGB color profile is so commonly used that we offer a canonical skcms_ICCProfile for it. |
| SKCMS_API const skcms_ICCProfile* skcms_sRGB_profile(void); |
| // Ditto for XYZD50, the most common profile connection space. |
| SKCMS_API const skcms_ICCProfile* skcms_XYZD50_profile(void); |
| |
| SKCMS_API const skcms_TransferFunction* skcms_sRGB_TransferFunction(void); |
| SKCMS_API const skcms_TransferFunction* skcms_sRGB_Inverse_TransferFunction(void); |
| SKCMS_API const skcms_TransferFunction* skcms_Identity_TransferFunction(void); |
| |
| // Practical equality test for two skcms_ICCProfiles. |
| // The implementation is subject to change, but it will always try to answer |
| // "can I substitute A for B?" and "can I skip transforming from A to B?". |
| SKCMS_API bool skcms_ApproximatelyEqualProfiles(const skcms_ICCProfile* A, |
| const skcms_ICCProfile* B); |
| |
| // Practical test that answers: Is curve roughly the inverse of inv_tf? Typically used by passing |
| // the inverse of a known parametric transfer function (like sRGB), to determine if a particular |
| // curve is very close to sRGB. |
| SKCMS_API bool skcms_AreApproximateInverses(const skcms_Curve* curve, |
| const skcms_TransferFunction* inv_tf); |
| |
| // Similar to above, answering the question for all three TRC curves of the given profile. Again, |
| // passing skcms_sRGB_InverseTransferFunction as inv_tf will answer the question: |
| // "Does this profile have a transfer function that is very close to sRGB?" |
| SKCMS_API bool skcms_TRCs_AreApproximateInverse(const skcms_ICCProfile* profile, |
| const skcms_TransferFunction* inv_tf); |
| |
| // Parse an ICC profile and return true if possible, otherwise return false. |
| // Selects an A2B profile (if present) according to priority list (each entry 0-2). |
| // The buffer is not copied; it must remain valid as long as the skcms_ICCProfile will be used. |
| SKCMS_API bool skcms_ParseWithA2BPriority(const void*, size_t, |
| const int priority[], int priorities, |
| skcms_ICCProfile*); |
| |
| static inline bool skcms_Parse(const void* buf, size_t len, skcms_ICCProfile* profile) { |
| // For continuity of existing user expectations, |
| // prefer A2B0 (perceptual) over A2B1 (relative colormetric), and ignore A2B2 (saturation). |
| const int priority[] = {0,1}; |
| return skcms_ParseWithA2BPriority(buf, len, |
| priority, sizeof(priority)/sizeof(*priority), |
| profile); |
| } |
| |
| SKCMS_API bool skcms_ApproximateCurve(const skcms_Curve* curve, |
| skcms_TransferFunction* approx, |
| float* max_error); |
| |
| SKCMS_API bool skcms_GetCHAD(const skcms_ICCProfile*, skcms_Matrix3x3*); |
| SKCMS_API bool skcms_GetWTPT(const skcms_ICCProfile*, float xyz[3]); |
| |
| // Returns the number of channels of input data that are expected on the "A" side of the profile. |
| // This is useful for image codecs, where the image data and the accompanying profile might have |
| // conflicting data shapes. In some cases, the result is unclear or invalid. In that case, the |
| // function will return a negative value to signal an error. |
| SKCMS_API int skcms_GetInputChannelCount(const skcms_ICCProfile*); |
| |
| // These are common ICC signature values |
| enum { |
| // common data_color_space values |
| skcms_Signature_CMYK = 0x434D594B, |
| skcms_Signature_Gray = 0x47524159, |
| skcms_Signature_RGB = 0x52474220, |
| |
| // pcs (or data_color_space) |
| skcms_Signature_Lab = 0x4C616220, |
| skcms_Signature_XYZ = 0x58595A20, |
| |
| // other, less common data_color_space values |
| skcms_Signature_CIELUV = 0x4C757620, |
| skcms_Signature_YCbCr = 0x59436272, |
| skcms_Signature_CIEYxy = 0x59787920, |
| skcms_Signature_HSV = 0x48535620, |
| skcms_Signature_HLS = 0x484C5320, |
| skcms_Signature_CMY = 0x434D5920, |
| skcms_Signature_2CLR = 0x32434C52, |
| skcms_Signature_3CLR = 0x33434C52, |
| skcms_Signature_4CLR = 0x34434C52, |
| skcms_Signature_5CLR = 0x35434C52, |
| skcms_Signature_6CLR = 0x36434C52, |
| skcms_Signature_7CLR = 0x37434C52, |
| skcms_Signature_8CLR = 0x38434C52, |
| skcms_Signature_9CLR = 0x39434C52, |
| skcms_Signature_10CLR = 0x41434C52, |
| skcms_Signature_11CLR = 0x42434C52, |
| skcms_Signature_12CLR = 0x43434C52, |
| skcms_Signature_13CLR = 0x44434C52, |
| skcms_Signature_14CLR = 0x45434C52, |
| skcms_Signature_15CLR = 0x46434C52, |
| }; |
| |
| typedef enum skcms_PixelFormat { |
| skcms_PixelFormat_A_8, |
| skcms_PixelFormat_A_8_, |
| skcms_PixelFormat_G_8, |
| skcms_PixelFormat_G_8_, |
| skcms_PixelFormat_GA_88, // Grayscale with alpha. |
| skcms_PixelFormat_GA_88_, |
| |
| skcms_PixelFormat_RGB_565, |
| skcms_PixelFormat_BGR_565, |
| |
| skcms_PixelFormat_ABGR_4444, |
| skcms_PixelFormat_ARGB_4444, |
| |
| skcms_PixelFormat_RGB_888, |
| skcms_PixelFormat_BGR_888, |
| skcms_PixelFormat_RGBA_8888, |
| skcms_PixelFormat_BGRA_8888, |
| skcms_PixelFormat_RGBA_8888_sRGB, // Automatic sRGB encoding / decoding. |
| skcms_PixelFormat_BGRA_8888_sRGB, // (Generally used with linear transfer functions.) |
| |
| skcms_PixelFormat_RGBA_1010102, |
| skcms_PixelFormat_BGRA_1010102, |
| |
| skcms_PixelFormat_RGB_161616LE, // Little-endian. Pointers must be 16-bit aligned. |
| skcms_PixelFormat_BGR_161616LE, |
| skcms_PixelFormat_RGBA_16161616LE, |
| skcms_PixelFormat_BGRA_16161616LE, |
| |
| skcms_PixelFormat_RGB_161616BE, // Big-endian. Pointers must be 16-bit aligned. |
| skcms_PixelFormat_BGR_161616BE, |
| skcms_PixelFormat_RGBA_16161616BE, |
| skcms_PixelFormat_BGRA_16161616BE, |
| |
| skcms_PixelFormat_RGB_hhh_Norm, // 1-5-10 half-precision float in [0,1] |
| skcms_PixelFormat_BGR_hhh_Norm, // Pointers must be 16-bit aligned. |
| skcms_PixelFormat_RGBA_hhhh_Norm, |
| skcms_PixelFormat_BGRA_hhhh_Norm, |
| |
| skcms_PixelFormat_RGB_hhh, // 1-5-10 half-precision float. |
| skcms_PixelFormat_BGR_hhh, // Pointers must be 16-bit aligned. |
| skcms_PixelFormat_RGBA_hhhh, |
| skcms_PixelFormat_BGRA_hhhh, |
| |
| skcms_PixelFormat_RGB_fff, // 1-8-23 single-precision float (the normal kind). |
| skcms_PixelFormat_BGR_fff, // Pointers must be 32-bit aligned. |
| skcms_PixelFormat_RGBA_ffff, |
| skcms_PixelFormat_BGRA_ffff, |
| |
| skcms_PixelFormat_RGB_101010x_XR, // Note: This is located here to signal no clamping. |
| skcms_PixelFormat_BGR_101010x_XR, // Compatible with MTLPixelFormatBGR10_XR. |
| skcms_PixelFormat_RGBA_10101010_XR, // Note: This is located here to signal no clamping. |
| skcms_PixelFormat_BGRA_10101010_XR, // Compatible with MTLPixelFormatBGRA10_XR. |
| } skcms_PixelFormat; |
| |
| // We always store any alpha channel linearly. In the chart below, tf-1() is the inverse |
| // transfer function for the given color profile (applying the transfer function linearizes). |
| |
| // We treat opaque as a strong requirement, not just a performance hint: we will ignore |
| // any source alpha and treat it as 1.0, and will make sure that any destination alpha |
| // channel is filled with the equivalent of 1.0. |
| |
| // We used to offer multiple types of premultiplication, but now just one, PremulAsEncoded. |
| // This is the premul you're probably used to working with. |
| |
| typedef enum skcms_AlphaFormat { |
| skcms_AlphaFormat_Opaque, // alpha is always opaque |
| // tf-1(r), tf-1(g), tf-1(b), 1.0 |
| skcms_AlphaFormat_Unpremul, // alpha and color are unassociated |
| // tf-1(r), tf-1(g), tf-1(b), a |
| skcms_AlphaFormat_PremulAsEncoded, // premultiplied while encoded |
| // tf-1(r)*a, tf-1(g)*a, tf-1(b)*a, a |
| } skcms_AlphaFormat; |
| |
| // Convert npixels pixels from src format and color profile to dst format and color profile |
| // and return true, otherwise return false. It is safe to alias dst == src if dstFmt == srcFmt. |
| SKCMS_API bool skcms_Transform(const void* src, |
| skcms_PixelFormat srcFmt, |
| skcms_AlphaFormat srcAlpha, |
| const skcms_ICCProfile* srcProfile, |
| void* dst, |
| skcms_PixelFormat dstFmt, |
| skcms_AlphaFormat dstAlpha, |
| const skcms_ICCProfile* dstProfile, |
| size_t npixels); |
| |
| // If profile can be used as a destination in skcms_Transform, return true. Otherwise, attempt to |
| // rewrite it with approximations where reasonable. If successful, return true. If no reasonable |
| // approximation exists, leave the profile unchanged and return false. |
| SKCMS_API bool skcms_MakeUsableAsDestination(skcms_ICCProfile* profile); |
| |
| // If profile can be used as a destination with a single parametric transfer function (ie for |
| // rasterization), return true. Otherwise, attempt to rewrite it with approximations where |
| // reasonable. If successful, return true. If no reasonable approximation exists, leave the |
| // profile unchanged and return false. |
| SKCMS_API bool skcms_MakeUsableAsDestinationWithSingleCurve(skcms_ICCProfile* profile); |
| |
| // Returns a matrix to adapt XYZ color from given the whitepoint to D50. |
| SKCMS_API bool skcms_AdaptToXYZD50(float wx, float wy, |
| skcms_Matrix3x3* toXYZD50); |
| |
| // Returns a matrix to convert RGB color into XYZ adapted to D50, given the |
| // primaries and whitepoint of the RGB model. |
| SKCMS_API bool skcms_PrimariesToXYZD50(float rx, float ry, |
| float gx, float gy, |
| float bx, float by, |
| float wx, float wy, |
| skcms_Matrix3x3* toXYZD50); |
| |
| // Call before your first call to skcms_Transform() to skip runtime CPU detection. |
| SKCMS_API void skcms_DisableRuntimeCPUDetection(void); |
| |
| // Utilities for programmatically constructing profiles |
| static inline void skcms_Init(skcms_ICCProfile* p) { |
| memset(p, 0, sizeof(*p)); |
| p->data_color_space = skcms_Signature_RGB; |
| p->pcs = skcms_Signature_XYZ; |
| } |
| |
| static inline void skcms_SetTransferFunction(skcms_ICCProfile* p, |
| const skcms_TransferFunction* tf) { |
| p->has_trc = true; |
| for (int i = 0; i < 3; ++i) { |
| p->trc[i].table_entries = 0; |
| p->trc[i].parametric = *tf; |
| } |
| } |
| |
| static inline void skcms_SetXYZD50(skcms_ICCProfile* p, const skcms_Matrix3x3* m) { |
| p->has_toXYZD50 = true; |
| p->toXYZD50 = *m; |
| } |
| |
| #ifdef __cplusplus |
| } |
| #endif |