| /* |
| * 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.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; |
| |
| // 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; |
| |
| // 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; |
| |
| typedef struct skcms_A2B { |
| // Optional: N 1D 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 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 curves. Always present, and output_channels must be 3. |
| uint32_t output_channels; |
| skcms_Curve output_curves[3]; |
| } skcms_A2B; |
| |
| 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 tag, skcms_Parse() sets A2B to that data, |
| // and has_A2B to true. |
| bool has_A2B; |
| skcms_A2B A2B; |
| } 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. |
| // The buffer is not copied, it must remain valid as long as the skcms_ICCProfile |
| // will be used. |
| SKCMS_API bool skcms_Parse(const void*, size_t, skcms_ICCProfile*); |
| |
| // No-op, to be removed. |
| static inline void skcms_OptimizeForSpeed(skcms_ICCProfile* p) { (void)p; } |
| |
| SKCMS_API bool skcms_ApproximateCurve(const skcms_Curve* curve, |
| skcms_TransferFunction* approx, |
| float* max_error); |
| |
| typedef struct skcms_ICCTag { |
| uint32_t signature; |
| uint32_t type; |
| uint32_t size; |
| const uint8_t* buf; |
| } skcms_ICCTag; |
| |
| SKCMS_API void skcms_GetTagByIndex (const skcms_ICCProfile*, uint32_t idx, skcms_ICCTag*); |
| SKCMS_API bool skcms_GetTagBySignature(const skcms_ICCProfile*, uint32_t sig, skcms_ICCTag*); |
| |
| // These are common ICC signature values |
| enum { |
| // data_color_space |
| skcms_Signature_CMYK = 0x434D594B, |
| skcms_Signature_Gray = 0x47524159, |
| skcms_Signature_RGB = 0x52474220, |
| |
| // pcs |
| skcms_Signature_Lab = 0x4C616220, |
| skcms_Signature_XYZ = 0x58595A20, |
| }; |
| |
| typedef enum skcms_PixelFormat { |
| skcms_PixelFormat_A_8, |
| skcms_PixelFormat_A_8_, |
| skcms_PixelFormat_G_8, |
| skcms_PixelFormat_G_8_, |
| |
| 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_1010102, |
| skcms_PixelFormat_BGRA_1010102, |
| |
| skcms_PixelFormat_RGB_161616, // Big-endian. Pointers must be 16-bit aligned. |
| skcms_PixelFormat_BGR_161616, |
| skcms_PixelFormat_RGBA_16161616, |
| skcms_PixelFormat_BGRA_16161616, |
| |
| 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; |
| |
| // 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. |
| |
| // When premultiplying and/or using a non-linear transfer function, it's important |
| // that we know the order the operations are applied. If you're used to working |
| // with non-color-managed drawing systems, PremulAsEncoded is probably the "premul" |
| // you're looking for; if you want linear blending, PremulLinear is the choice for you. |
| |
| 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_PremulLinear, // premultiplied while linear |
| // 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); |
| |
| SKCMS_API bool skcms_PrimariesToXYZD50(float rx, float ry, |
| float gx, float gy, |
| float bx, float by, |
| float wx, float wy, |
| skcms_Matrix3x3* toXYZD50); |
| |
| // 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 |