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Diffstat (limited to 'Userland/Libraries/LibGfx/ICC/Profile.cpp')
| -rw-r--r-- | Userland/Libraries/LibGfx/ICC/Profile.cpp | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/Userland/Libraries/LibGfx/ICC/Profile.cpp b/Userland/Libraries/LibGfx/ICC/Profile.cpp index 91d15a0f12..e0b4c5b44d 100644 --- a/Userland/Libraries/LibGfx/ICC/Profile.cpp +++ b/Userland/Libraries/LibGfx/ICC/Profile.cpp @@ -1470,6 +1470,59 @@ ErrorOr<FloatVector3> Profile::to_pcs(ReadonlyBytes color) VERIFY_NOT_REACHED(); } +ErrorOr<Profile::CIELAB> Profile::to_lab(ReadonlyBytes color) +{ + auto pcs = TRY(to_pcs(color)); + if (connection_space() == ColorSpace::PCSLAB) + return CIELAB { pcs[0], pcs[1], pcs[2] }; + + if (connection_space() != ColorSpace::PCSXYZ) { + VERIFY(device_class() == DeviceClass::DeviceLink); + return Error::from_string_literal("ICC::Profile::to_lab: conversion for DeviceLink not implemented"); + } + + // 6.3.2.2 Translation between media-relative colorimetric data and ICC-absolute colorimetric data + // 6.3.2.3 Computation of PCSLAB + // 6.3.4 Colour space encodings for the PCS + // A.3 PCS encodings + + auto f = [](float x) { + if (x > powf(6.f / 29.f, 3)) + return cbrtf(x); + return x / (3 * powf(6.f / 29.f, 2)) + 4.f / 29.f; + }; + + // "X/Xn is replaced by Xr/Xi (or Xa/Xmw)" + + // 6.3.2.2 Translation between media-relative colorimetric data and ICC-absolute colorimetric data + // "The translation from ICC-absolute colorimetric data to media-relative colorimetry data is given by Equations + // Xr = (Xi/Xmw) * Xa + // where + // Xr media-relative colorimetric data (i.e. PCSXYZ); + // Xa ICC-absolute colorimetric data (i.e. nCIEXYZ); + // Xmw nCIEXYZ values of the media white point as specified in the mediaWhitePointTag; + // Xi PCSXYZ values of the PCS white point defined in 6.3.4.3." + // 6.3.4.3 PCS encodings for white and black + // "Table 14 — Encodings of PCS white point: X 0,9642 Y 1,0000 Z 0,8249" + // That's identical to the values in 7.2.16 PCS illuminant field (Bytes 68 to 79). + // 9.2.36 mediaWhitePointTag + // "For displays, the values specified shall be those of the PCS illuminant as defined in 7.2.16." + // ...so for displays, this is all equivalent I think? It's maybe different for OutputDevice profiles? + + float Xn = pcs_illuminant().X; + float Yn = pcs_illuminant().Y; + float Zn = pcs_illuminant().Z; + + float x = pcs[0] / Xn; + float y = pcs[1] / Yn; + float z = pcs[2] / Zn; + + float L = 116 * f(y) - 16; + float a = 500 * (f(x) - f(y)); + float b = 200 * (f(y) - f(z)); + return CIELAB { L, a, b }; +} + XYZ const& Profile::red_matrix_column() const { return xyz_data(redMatrixColumnTag); } XYZ const& Profile::green_matrix_column() const { return xyz_data(greenMatrixColumnTag); } XYZ const& Profile::blue_matrix_column() const { return xyz_data(blueMatrixColumnTag); } |