| /* |
| * Copyright 2016 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "include/core/SkICC.h" |
| #include "include/private/SkFixed.h" |
| #include "src/core/SkAutoMalloc.h" |
| #include "src/core/SkColorSpacePriv.h" |
| #include "src/core/SkEndian.h" |
| #include "src/core/SkICCPriv.h" |
| #include "src/core/SkMD5.h" |
| #include "src/core/SkUtils.h" |
| |
| static constexpr char kDescriptionTagBodyPrefix[12] = |
| { 'G', 'o', 'o', 'g', 'l', 'e', '/', 'S', 'k', 'i', 'a' , '/'}; |
| |
| static constexpr size_t kICCDescriptionTagSize = 44; |
| |
| static_assert(kICCDescriptionTagSize == |
| sizeof(kDescriptionTagBodyPrefix) + 2 * sizeof(SkMD5::Digest), ""); |
| static constexpr size_t kDescriptionTagBodySize = kICCDescriptionTagSize * 2; // ascii->utf16be |
| |
| static_assert(SkIsAlign4(kDescriptionTagBodySize), "Description must be aligned to 4-bytes."); |
| static constexpr uint32_t kDescriptionTagHeader[7] { |
| SkEndian_SwapBE32(kTAG_TextType), // Type signature |
| 0, // Reserved |
| SkEndian_SwapBE32(1), // Number of records |
| SkEndian_SwapBE32(12), // Record size (must be 12) |
| SkEndian_SwapBE32(SkSetFourByteTag('e', 'n', 'U', 'S')), // English USA |
| SkEndian_SwapBE32(kDescriptionTagBodySize), // Length of string |
| SkEndian_SwapBE32(28), // Offset of string |
| }; |
| |
| static constexpr uint32_t kWhitePointTag[5] { |
| SkEndian_SwapBE32(kXYZ_PCSSpace), |
| 0, |
| SkEndian_SwapBE32(0x0000f6d6), // X = 0.96420 (D50) |
| SkEndian_SwapBE32(0x00010000), // Y = 1.00000 (D50) |
| SkEndian_SwapBE32(0x0000d32d), // Z = 0.82491 (D50) |
| }; |
| |
| // Google Inc. 2016 (UTF-16) |
| static constexpr uint8_t kCopyrightTagBody[] = { |
| 0x00, 0x47, 0x00, 0x6f, |
| 0x00, 0x6f, 0x00, 0x67, |
| 0x00, 0x6c, 0x00, 0x65, |
| 0x00, 0x20, 0x00, 0x49, |
| 0x00, 0x6e, 0x00, 0x63, |
| 0x00, 0x2e, 0x00, 0x20, |
| 0x00, 0x32, 0x00, 0x30, |
| 0x00, 0x31, 0x00, 0x36, |
| }; |
| static_assert(SkIsAlign4(sizeof(kCopyrightTagBody)), "Copyright must be aligned to 4-bytes."); |
| static constexpr uint32_t kCopyrightTagHeader[7] { |
| SkEndian_SwapBE32(kTAG_TextType), // Type signature |
| 0, // Reserved |
| SkEndian_SwapBE32(1), // Number of records |
| SkEndian_SwapBE32(12), // Record size (must be 12) |
| SkEndian_SwapBE32(SkSetFourByteTag('e', 'n', 'U', 'S')), // English USA |
| SkEndian_SwapBE32(sizeof(kCopyrightTagBody)), // Length of string |
| SkEndian_SwapBE32(28), // Offset of string |
| }; |
| |
| // We will write a profile with the minimum nine required tags. |
| static constexpr uint32_t kICCNumEntries = 9; |
| |
| static constexpr uint32_t kTAG_desc = SkSetFourByteTag('d', 'e', 's', 'c'); |
| static constexpr uint32_t kTAG_desc_Bytes = sizeof(kDescriptionTagHeader) + |
| kDescriptionTagBodySize; |
| static constexpr uint32_t kTAG_desc_Offset = kICCHeaderSize + |
| kICCNumEntries * kICCTagTableEntrySize; |
| |
| static constexpr uint32_t kTAG_XYZ_Bytes = 20; |
| static constexpr uint32_t kTAG_rXYZ_Offset = kTAG_desc_Offset + kTAG_desc_Bytes; |
| static constexpr uint32_t kTAG_gXYZ_Offset = kTAG_rXYZ_Offset + kTAG_XYZ_Bytes; |
| static constexpr uint32_t kTAG_bXYZ_Offset = kTAG_gXYZ_Offset + kTAG_XYZ_Bytes; |
| |
| static constexpr uint32_t kTAG_TRC_Bytes = 40; |
| static constexpr uint32_t kTAG_rTRC_Offset = kTAG_bXYZ_Offset + kTAG_XYZ_Bytes; |
| static constexpr uint32_t kTAG_gTRC_Offset = kTAG_rTRC_Offset; |
| static constexpr uint32_t kTAG_bTRC_Offset = kTAG_rTRC_Offset; |
| |
| static constexpr uint32_t kTAG_wtpt = SkSetFourByteTag('w', 't', 'p', 't'); |
| static constexpr uint32_t kTAG_wtpt_Offset = kTAG_bTRC_Offset + kTAG_TRC_Bytes; |
| |
| static constexpr uint32_t kTAG_cprt = SkSetFourByteTag('c', 'p', 'r', 't'); |
| static constexpr uint32_t kTAG_cprt_Bytes = sizeof(kCopyrightTagHeader) + |
| sizeof(kCopyrightTagBody); |
| static constexpr uint32_t kTAG_cprt_Offset = kTAG_wtpt_Offset + kTAG_XYZ_Bytes; |
| |
| static constexpr uint32_t kICCProfileSize = kTAG_cprt_Offset + kTAG_cprt_Bytes; |
| |
| static constexpr uint32_t kICCHeader[kICCHeaderSize / 4] { |
| SkEndian_SwapBE32(kICCProfileSize), // Size of the profile |
| 0, // Preferred CMM type (ignored) |
| SkEndian_SwapBE32(0x04300000), // Version 4.3 |
| SkEndian_SwapBE32(kDisplay_Profile), // Display device profile |
| SkEndian_SwapBE32(kRGB_ColorSpace), // RGB input color space |
| SkEndian_SwapBE32(kXYZ_PCSSpace), // XYZ profile connection space |
| 0, 0, 0, // Date and time (ignored) |
| SkEndian_SwapBE32(kACSP_Signature), // Profile signature |
| 0, // Platform target (ignored) |
| 0x00000000, // Flags: not embedded, can be used independently |
| 0, // Device manufacturer (ignored) |
| 0, // Device model (ignored) |
| 0, 0, // Device attributes (ignored) |
| SkEndian_SwapBE32(1), // Relative colorimetric rendering intent |
| SkEndian_SwapBE32(0x0000f6d6), // D50 standard illuminant (X) |
| SkEndian_SwapBE32(0x00010000), // D50 standard illuminant (Y) |
| SkEndian_SwapBE32(0x0000d32d), // D50 standard illuminant (Z) |
| 0, // Profile creator (ignored) |
| 0, 0, 0, 0, // Profile id checksum (ignored) |
| 0, 0, 0, 0, 0, 0, 0, // Reserved (ignored) |
| SkEndian_SwapBE32(kICCNumEntries), // Number of tags |
| }; |
| |
| static constexpr uint32_t kICCTagTable[3 * kICCNumEntries] { |
| // Profile description |
| SkEndian_SwapBE32(kTAG_desc), |
| SkEndian_SwapBE32(kTAG_desc_Offset), |
| SkEndian_SwapBE32(kTAG_desc_Bytes), |
| |
| // rXYZ |
| SkEndian_SwapBE32(kTAG_rXYZ), |
| SkEndian_SwapBE32(kTAG_rXYZ_Offset), |
| SkEndian_SwapBE32(kTAG_XYZ_Bytes), |
| |
| // gXYZ |
| SkEndian_SwapBE32(kTAG_gXYZ), |
| SkEndian_SwapBE32(kTAG_gXYZ_Offset), |
| SkEndian_SwapBE32(kTAG_XYZ_Bytes), |
| |
| // bXYZ |
| SkEndian_SwapBE32(kTAG_bXYZ), |
| SkEndian_SwapBE32(kTAG_bXYZ_Offset), |
| SkEndian_SwapBE32(kTAG_XYZ_Bytes), |
| |
| // rTRC |
| SkEndian_SwapBE32(kTAG_rTRC), |
| SkEndian_SwapBE32(kTAG_rTRC_Offset), |
| SkEndian_SwapBE32(kTAG_TRC_Bytes), |
| |
| // gTRC |
| SkEndian_SwapBE32(kTAG_gTRC), |
| SkEndian_SwapBE32(kTAG_gTRC_Offset), |
| SkEndian_SwapBE32(kTAG_TRC_Bytes), |
| |
| // bTRC |
| SkEndian_SwapBE32(kTAG_bTRC), |
| SkEndian_SwapBE32(kTAG_bTRC_Offset), |
| SkEndian_SwapBE32(kTAG_TRC_Bytes), |
| |
| // White point |
| SkEndian_SwapBE32(kTAG_wtpt), |
| SkEndian_SwapBE32(kTAG_wtpt_Offset), |
| SkEndian_SwapBE32(kTAG_XYZ_Bytes), |
| |
| // Copyright |
| SkEndian_SwapBE32(kTAG_cprt), |
| SkEndian_SwapBE32(kTAG_cprt_Offset), |
| SkEndian_SwapBE32(kTAG_cprt_Bytes), |
| }; |
| |
| // This is like SkFloatToFixed, but rounds to nearest, preserving as much accuracy as possible |
| // when going float -> fixed -> float (it has the same accuracy when going fixed -> float -> fixed). |
| // The use of double is necessary to accommodate the full potential 32-bit mantissa of the 16.16 |
| // SkFixed value, and so avoiding rounding problems with float. Also, see the comment in SkFixed.h. |
| static SkFixed float_round_to_fixed(float x) { |
| return sk_float_saturate2int((float)floor((double)x * SK_Fixed1 + 0.5)); |
| } |
| |
| static void write_xyz_tag(uint32_t* ptr, const skcms_Matrix3x3& toXYZD50, int col) { |
| ptr[0] = SkEndian_SwapBE32(kXYZ_PCSSpace); |
| ptr[1] = 0; |
| ptr[2] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[0][col])); |
| ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[1][col])); |
| ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[2][col])); |
| } |
| |
| static void write_trc_tag(uint32_t* ptr, const skcms_TransferFunction& fn) { |
| ptr[0] = SkEndian_SwapBE32(kTAG_ParaCurveType); |
| ptr[1] = 0; |
| ptr[2] = (uint32_t) (SkEndian_SwapBE16(kGABCDEF_ParaCurveType)); |
| ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(fn.g)); |
| ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(fn.a)); |
| ptr[5] = SkEndian_SwapBE32(float_round_to_fixed(fn.b)); |
| ptr[6] = SkEndian_SwapBE32(float_round_to_fixed(fn.c)); |
| ptr[7] = SkEndian_SwapBE32(float_round_to_fixed(fn.d)); |
| ptr[8] = SkEndian_SwapBE32(float_round_to_fixed(fn.e)); |
| ptr[9] = SkEndian_SwapBE32(float_round_to_fixed(fn.f)); |
| } |
| |
| static bool nearly_equal(float x, float y) { |
| // A note on why I chose this tolerance: transfer_fn_almost_equal() uses a |
| // tolerance of 0.001f, which doesn't seem to be enough to distinguish |
| // between similar transfer functions, for example: gamma2.2 and sRGB. |
| // |
| // If the tolerance is 0.0f, then this we can't distinguish between two |
| // different encodings of what is clearly the same colorspace. Some |
| // experimentation with example files lead to this number: |
| static constexpr float kTolerance = 1.0f / (1 << 11); |
| return ::fabsf(x - y) <= kTolerance; |
| } |
| |
| static bool nearly_equal(const skcms_TransferFunction& u, |
| const skcms_TransferFunction& v) { |
| return nearly_equal(u.g, v.g) |
| && nearly_equal(u.a, v.a) |
| && nearly_equal(u.b, v.b) |
| && nearly_equal(u.c, v.c) |
| && nearly_equal(u.d, v.d) |
| && nearly_equal(u.e, v.e) |
| && nearly_equal(u.f, v.f); |
| } |
| |
| static bool nearly_equal(const skcms_Matrix3x3& u, const skcms_Matrix3x3& v) { |
| for (int r = 0; r < 3; r++) { |
| for (int c = 0; c < 3; c++) { |
| if (!nearly_equal(u.vals[r][c], v.vals[r][c])) { |
| return false; |
| } |
| } |
| } |
| return true; |
| } |
| |
| // Return nullptr if the color profile doen't have a special name. |
| const char* get_color_profile_description(const skcms_TransferFunction& fn, |
| const skcms_Matrix3x3& toXYZD50) { |
| bool srgb_xfer = nearly_equal(fn, SkNamedTransferFn::kSRGB); |
| bool srgb_gamut = nearly_equal(toXYZD50, SkNamedGamut::kSRGB); |
| if (srgb_xfer && srgb_gamut) { |
| return "sRGB"; |
| } |
| bool line_xfer = nearly_equal(fn, SkNamedTransferFn::kLinear); |
| if (line_xfer && srgb_gamut) { |
| return "Linear Transfer with sRGB Gamut"; |
| } |
| bool twoDotTwo = nearly_equal(fn, SkNamedTransferFn::k2Dot2); |
| if (twoDotTwo && srgb_gamut) { |
| return "2.2 Transfer with sRGB Gamut"; |
| } |
| if (twoDotTwo && nearly_equal(toXYZD50, SkNamedGamut::kAdobeRGB)) { |
| return "AdobeRGB"; |
| } |
| bool display_p3 = nearly_equal(toXYZD50, SkNamedGamut::kDisplayP3); |
| if (srgb_xfer || line_xfer) { |
| if (srgb_xfer && display_p3) { |
| return "sRGB Transfer with Display P3 Gamut"; |
| } |
| if (line_xfer && display_p3) { |
| return "Linear Transfer with Display P3 Gamut"; |
| } |
| bool rec2020 = nearly_equal(toXYZD50, SkNamedGamut::kRec2020); |
| if (srgb_xfer && rec2020) { |
| return "sRGB Transfer with Rec-BT-2020 Gamut"; |
| } |
| if (line_xfer && rec2020) { |
| return "Linear Transfer with Rec-BT-2020 Gamut"; |
| } |
| } |
| return nullptr; |
| } |
| |
| static void get_color_profile_tag(char dst[kICCDescriptionTagSize], |
| const skcms_TransferFunction& fn, |
| const skcms_Matrix3x3& toXYZD50) { |
| SkASSERT(dst); |
| if (const char* description = get_color_profile_description(fn, toXYZD50)) { |
| SkASSERT(strlen(description) < kICCDescriptionTagSize); |
| |
| // Without these extra (), GCC would warn us something like |
| // ... sepecified bound 44 equals destination size ... |
| // which, yeah, is exactly what we're trying to do, copy the string |
| // and zero the rest of the destination if any. Sheesh. |
| (strncpy(dst, description, kICCDescriptionTagSize)); |
| // "If the length of src is less than n, strncpy() writes additional |
| // null bytes to dest to ensure that a total of n bytes are written." |
| } else { |
| memcpy(dst, kDescriptionTagBodyPrefix, sizeof(kDescriptionTagBodyPrefix)); |
| SkMD5 md5; |
| md5.write(&toXYZD50, sizeof(toXYZD50)); |
| static_assert(sizeof(fn) == sizeof(float) * 7, "packed"); |
| md5.write(&fn, sizeof(fn)); |
| SkMD5::Digest digest = md5.finish(); |
| char* ptr = dst + sizeof(kDescriptionTagBodyPrefix); |
| for (unsigned i = 0; i < sizeof(SkMD5::Digest); ++i) { |
| uint8_t byte = digest.data[i]; |
| *ptr++ = SkHexadecimalDigits::gUpper[byte >> 4]; |
| *ptr++ = SkHexadecimalDigits::gUpper[byte & 0xF]; |
| } |
| SkASSERT(ptr == dst + kICCDescriptionTagSize); |
| } |
| } |
| |
| sk_sp<SkData> SkWriteICCProfile(const skcms_TransferFunction& fn, |
| const skcms_Matrix3x3& toXYZD50) { |
| // We can't encode HDR transfer functions in ICC |
| if (classify_transfer_fn(fn) != sRGBish_TF) { |
| return nullptr; |
| } |
| |
| SkAutoMalloc profile(kICCProfileSize); |
| uint8_t* ptr = (uint8_t*) profile.get(); |
| |
| // Write profile header |
| memcpy(ptr, kICCHeader, sizeof(kICCHeader)); |
| ptr += sizeof(kICCHeader); |
| |
| // Write tag table |
| memcpy(ptr, kICCTagTable, sizeof(kICCTagTable)); |
| ptr += sizeof(kICCTagTable); |
| |
| // Write profile description tag |
| memcpy(ptr, kDescriptionTagHeader, sizeof(kDescriptionTagHeader)); |
| ptr += sizeof(kDescriptionTagHeader); |
| { |
| char colorProfileTag[kICCDescriptionTagSize]; |
| get_color_profile_tag(colorProfileTag, fn, toXYZD50); |
| |
| // ASCII --> big-endian UTF-16. |
| for (size_t i = 0; i < kICCDescriptionTagSize; i++) { |
| *ptr++ = 0; |
| *ptr++ = colorProfileTag[i]; |
| } |
| } |
| |
| // Write XYZ tags |
| write_xyz_tag((uint32_t*) ptr, toXYZD50, 0); |
| ptr += kTAG_XYZ_Bytes; |
| write_xyz_tag((uint32_t*) ptr, toXYZD50, 1); |
| ptr += kTAG_XYZ_Bytes; |
| write_xyz_tag((uint32_t*) ptr, toXYZD50, 2); |
| ptr += kTAG_XYZ_Bytes; |
| |
| // Write TRC tag |
| write_trc_tag((uint32_t*) ptr, fn); |
| ptr += kTAG_TRC_Bytes; |
| |
| // Write white point tag (must be D50) |
| memcpy(ptr, kWhitePointTag, sizeof(kWhitePointTag)); |
| ptr += sizeof(kWhitePointTag); |
| |
| // Write copyright tag |
| memcpy(ptr, kCopyrightTagHeader, sizeof(kCopyrightTagHeader)); |
| ptr += sizeof(kCopyrightTagHeader); |
| memcpy(ptr, kCopyrightTagBody, sizeof(kCopyrightTagBody)); |
| ptr += sizeof(kCopyrightTagBody); |
| |
| SkASSERT(kICCProfileSize == ptr - (uint8_t*) profile.get()); |
| return SkData::MakeFromMalloc(profile.release(), kICCProfileSize); |
| } |
