mirror of
https://github.com/RGBCube/serenity
synced 2025-10-31 06:52:45 +00:00
90 lines
3.9 KiB
C++
90 lines
3.9 KiB
C++
/*
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* Copyright (c) 2023, Nico Weber <thakis@chromium.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibGfx/ICC/Profile.h>
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#include <LibGfx/ICC/Tags.h>
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#include <LibGfx/ICC/WellKnownProfiles.h>
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#include <time.h>
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namespace Gfx::ICC {
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static ProfileHeader rgb_header()
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{
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ProfileHeader header;
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header.version = Version(4, 0x40);
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header.device_class = DeviceClass::DisplayDevice;
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header.data_color_space = ColorSpace::RGB;
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header.connection_space = ColorSpace::PCSXYZ;
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header.creation_timestamp = time(NULL);
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header.rendering_intent = RenderingIntent::Perceptual;
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header.pcs_illuminant = XYZ { 0.9642, 1.0, 0.8249 };
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return header;
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}
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static ErrorOr<NonnullRefPtr<MultiLocalizedUnicodeTagData>> en_US(StringView text)
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{
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Vector<MultiLocalizedUnicodeTagData::Record> records;
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TRY(records.try_append({ ('e' << 8) | 'n', ('U' << 8) | 'S', TRY(String::from_utf8(text)) }));
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return try_make_ref_counted<MultiLocalizedUnicodeTagData>(0, 0, records);
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}
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static ErrorOr<NonnullRefPtr<XYZTagData>> XYZ_data(XYZ xyz)
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{
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Vector<XYZ> xyzs;
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TRY(xyzs.try_append(xyz));
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return try_make_ref_counted<XYZTagData>(0, 0, move(xyzs));
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}
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ErrorOr<NonnullRefPtr<TagData>> sRGB_curve()
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{
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// Numbers from https://en.wikipedia.org/wiki/SRGB#From_sRGB_to_CIE_XYZ
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Array<S15Fixed16, 7> curve_parameters = { 2.4, 1 / 1.055, 0.055 / 1.055, 1 / 12.92, 0.04045 };
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return try_make_ref_counted<ParametricCurveTagData>(0, 0, ParametricCurveTagData::FunctionType::sRGB, curve_parameters);
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}
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ErrorOr<NonnullRefPtr<Profile>> sRGB()
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{
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// Returns an sRGB profile.
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// https://en.wikipedia.org/wiki/SRGB
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// FIXME: There are many different sRGB ICC profiles in the wild.
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// Explain why, and why this picks the numbers it does.
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// In the meantime, https://github.com/SerenityOS/serenity/pull/17714 has a few notes.
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auto header = rgb_header();
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OrderedHashMap<TagSignature, NonnullRefPtr<TagData>> tag_table;
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TRY(tag_table.try_set(profileDescriptionTag, TRY(en_US("SerenityOS sRGB"sv))));
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TRY(tag_table.try_set(copyrightTag, TRY(en_US("Public Domain"sv))));
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// Transfer function.
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auto curve = TRY(sRGB_curve());
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TRY(tag_table.try_set(redTRCTag, curve));
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TRY(tag_table.try_set(greenTRCTag, curve));
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TRY(tag_table.try_set(blueTRCTag, curve));
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// White point.
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// ICC v4, 9.2.36 mediaWhitePointTag: "For displays, the values specified shall be those of the PCS illuminant as defined in 7.2.16."
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TRY(tag_table.try_set(mediaWhitePointTag, TRY(XYZ_data(header.pcs_illuminant))));
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// The chromatic_adaptation_matrix values are from https://www.color.org/chadtag.xalter
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// That leads to exactly the S15Fixed16 values in the sRGB profiles in GIMP, Android, RawTherapee (but not in Compact-ICC-Profiles's v4 sRGB profile).
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Vector<S15Fixed16, 9> chromatic_adaptation_matrix = { 1.047882, 0.022918, -0.050217, 0.029586, 0.990478, -0.017075, -0.009247, 0.015075, 0.751678 };
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TRY(tag_table.try_set(chromaticAdaptationTag, TRY(try_make_ref_counted<S15Fixed16ArrayTagData>(0, 0, move(chromatic_adaptation_matrix)))));
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// The chromaticity values are from https://www.color.org/srgb.pdf
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// The chromatic adaptation matrix in that document is slightly different from the one on https://www.color.org/chadtag.xalter,
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// so the values in our sRGB profile are currently not fully self-consistent.
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// FIXME: Make values self-consistent (probably by using slightly different chromaticities).
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TRY(tag_table.try_set(redMatrixColumnTag, TRY(XYZ_data(XYZ { 0.436030342570117, 0.222438466210245, 0.013897440074263 }))));
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TRY(tag_table.try_set(greenMatrixColumnTag, TRY(XYZ_data(XYZ { 0.385101860087134, 0.716942745571917, 0.097076381494207 }))));
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TRY(tag_table.try_set(blueMatrixColumnTag, TRY(XYZ_data(XYZ { 0.143067806654203, 0.060618777416563, 0.713926257896652 }))));
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return Profile::create(header, move(tag_table));
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}
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}
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