diff --git a/include/lsst/cpputils/_oklabTools.h b/include/lsst/cpputils/_oklabTools.h new file mode 100644 index 0000000..70d4409 --- /dev/null +++ b/include/lsst/cpputils/_oklabTools.h @@ -0,0 +1,421 @@ +/* +Copyright (c) 2021 Björn Ottosson +Copyright (c) 2024 The Trustees of Princeton University + +Permission is hereby granted, free of charge, to any person obtaining a copy of +this software and associated documentation files (the "Software"), to deal in +the Software without restriction, including without limitation the rights to +use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies +of the Software, and to permit persons to whom the Software is furnished to do +so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. + +Modified 2024 to us Display P3 Conversions - Princeton University +*/ + +#include +#include +#include + +namespace lsst { +namespace cpputils { +namespace details { + +struct Lab {float L; float a; float b;}; +struct RGB {float r; float g; float b;}; + +Lab linear_srgb_to_oklab(RGB c) +{ + float l = 0.4122214708f * c.r + 0.5363325363f * c.g + 0.0514459929f * c.b; + float m = 0.2119034982f * c.r + 0.6806995451f * c.g + 0.1073969566f * c.b; + float s = 0.0883024619f * c.r + 0.2817188376f * c.g + 0.6299787005f * c.b; + + float l_ = cbrtf(l); + float m_ = cbrtf(m); + float s_ = cbrtf(s); + + return { + 0.2104542553f * l_ + 0.7936177850f * m_ - 0.0040720468f * s_, + 1.9779984951f * l_ - 2.4285922050f * m_ + 0.4505937099f * s_, + 0.0259040371f * l_ + 0.7827717662f * m_ - 0.8086757660f * s_, + }; +} + +Lab linear_displayP3_to_oklab(RGB c) +{ + float l = 0.48132729f * c.r + 0.46206791f * c.g + 00.0564956f * c.b; + float m = 0.2288381f * c.r + 0.6532344f * c.g + 0.11795441f * c.b; + float s = 0.08398602f * c.r + 0.22427279f * c.g + 0.69222084f * c.b; + + float l_ = cbrtf(l); + float m_ = cbrtf(m); + float s_ = cbrtf(s); + + return { + 0.2104542553f * l_ + 0.7936177850f * m_ - 0.0040720468f * s_, + 1.9779984951f * l_ - 2.4285922050f * m_ + 0.4505937099f * s_, + 0.0259040371f * l_ + 0.7827717662f * m_ - 0.8086757660f * s_, + }; +} + + +RGB oklab_to_linear_srgb(Lab c) +{ + float l_ = c.L + 0.3963377774f * c.a + 0.2158037573f * c.b; + float m_ = c.L - 0.1055613458f * c.a - 0.0638541728f * c.b; + float s_ = c.L - 0.0894841775f * c.a - 1.2914855480f * c.b; + + float l = l_ * l_ * l_; + float m = m_ * m_ * m_; + float s = s_ * s_ * s_; + + return { + +4.0767416621f * l - 3.3077115913f * m + 0.2309699292f * s, + -1.2684380046f * l + 2.6097574011f * m - 0.3413193965f * s, + -0.0041960863f * l - 0.7034186147f * m + 1.7076147010f * s, + }; +} + +RGB oklab_to_linear_displayP3(Lab c) +{ + float l_ = c.L + 0.3963377774f * c.a + 0.2158037573f * c.b; + float m_ = c.L - 0.1055613458f * c.a - 0.0638541728f * c.b; + float s_ = c.L - 0.0894841775f * c.a - 1.2914855480f * c.b; + + float l = l_ * l_ * l_; + float m = m_ * m_ * m_; + float s = s_ * s_ * s_; + + return { + 3.12811053f * l - 2.25707502f * m + 0.12930479f * s, + -1.09112816f * l + 2.41326676f * m - 0.32216817f * s, + -0.02601365f * l - 0.50802765f * m + 1.53331668f * s, + }; +} + +// Finds the maximum saturation possible for a given hue that fits in sRGB +// Saturation here is defined as S = C/L +// a and b must be normalized so a^2 + b^2 == 1 +float compute_max_saturation(float a, float b) +{ + // Max saturation will be when one of r, g or b goes below zero. + + // Select different coefficients depending on which component goes below zero first + float k0, k1, k2, k3, k4, wl, wm, ws; + + if (-1.88170328f * a - 0.80936493f * b > 1) + { + // Red component + k0 = +1.19086277f; k1 = +1.76576728f; k2 = +0.59662641f; k3 = +0.75515197f; k4 = +0.56771245f; + wl = +4.0767416621f; wm = -3.3077115913f; ws = +0.2309699292f; + } + else if (1.81444104f * a - 1.19445276f * b > 1) + { + // Green component + k0 = +0.73956515f; k1 = -0.45954404f; k2 = +0.08285427f; k3 = +0.12541070f; k4 = +0.14503204f; + wl = -1.2684380046f; wm = +2.6097574011f; ws = -0.3413193965f; + } + else + { + // Blue component + k0 = +1.35733652f; k1 = -0.00915799f; k2 = -1.15130210f; k3 = -0.50559606f; k4 = +0.00692167f; + wl = -0.0041960863f; wm = -0.7034186147f; ws = +1.7076147010f; + } + + // Approximate max saturation using a polynomial: + float S = k0 + k1 * a + k2 * b + k3 * a * a + k4 * a * b; + + // Do one step Halley's method to get closer + // this gives an error less than 10e6, except for some blue hues where the dS/dh is close to infinite + // this should be sufficient for most applications, otherwise do two/three steps + + float k_l = +0.3963377774f * a + 0.2158037573f * b; + float k_m = -0.1055613458f * a - 0.0638541728f * b; + float k_s = -0.0894841775f * a - 1.2914855480f * b; + + { + float l_ = 1.f + S * k_l; + float m_ = 1.f + S * k_m; + float s_ = 1.f + S * k_s; + + float l = l_ * l_ * l_; + float m = m_ * m_ * m_; + float s = s_ * s_ * s_; + + float l_dS = 3.f * k_l * l_ * l_; + float m_dS = 3.f * k_m * m_ * m_; + float s_dS = 3.f * k_s * s_ * s_; + + float l_dS2 = 6.f * k_l * k_l * l_; + float m_dS2 = 6.f * k_m * k_m * m_; + float s_dS2 = 6.f * k_s * k_s * s_; + + float f = wl * l + wm * m + ws * s; + float f1 = wl * l_dS + wm * m_dS + ws * s_dS; + float f2 = wl * l_dS2 + wm * m_dS2 + ws * s_dS2; + + S = S - f * f1 / (f1*f1 - 0.5f * f * f2); + } + + return S; +} + +// finds L_cusp and C_cusp for a given hue +// a and b must be normalized so a^2 + b^2 == 1 +struct LC { float L; float C; }; +LC find_cusp(float a, float b) +{ + // First, find the maximum saturation (saturation S = C/L) + float S_cusp = compute_max_saturation(a, b); + + // Convert to linear sRGB to find the first point where at least one of r,g or b >= 1: + RGB rgb_at_max = oklab_to_linear_displayP3({ 1, S_cusp * a, S_cusp * b }); + float L_cusp = cbrtf(1.f / fmax(fmax(rgb_at_max.r, rgb_at_max.g), rgb_at_max.b)); + float C_cusp = L_cusp * S_cusp; + + return { L_cusp , C_cusp }; +} + +// Finds intersection of the line defined by +// L = L0 * (1 - t) + t * L1; +// C = t * C1; +// a and b must be normalized so a^2 + b^2 == 1 +float find_gamut_intersection(float a, float b, float L1, float C1, float L0) +{ + // Find the cusp of the gamut triangle + LC cusp = find_cusp(a, b); + + // Find the intersection for upper and lower half seprately + float t; + if (((L1 - L0) * cusp.C - (cusp.L - L0) * C1) <= 0.f) + { + // Lower half + + t = cusp.C * L0 / (C1 * cusp.L + cusp.C * (L0 - L1)); + } + else + { + // Upper half + + // First intersect with triangle + t = cusp.C * (L0 - 1.f) / (C1 * (cusp.L - 1.f) + cusp.C * (L0 - L1)); + + // Then one step Halley's method + { + float dL = L1 - L0; + float dC = C1; + + float k_l = +0.3963377774f * a + 0.2158037573f * b; + float k_m = -0.1055613458f * a - 0.0638541728f * b; + float k_s = -0.0894841775f * a - 1.2914855480f * b; + + float l_dt = dL + dC * k_l; + float m_dt = dL + dC * k_m; + float s_dt = dL + dC * k_s; + + + // If higher accuracy is required, 2 or 3 iterations of the following block can be used: + { + float L = L0 * (1.f - t) + t * L1; + float C = t * C1; + + float l_ = L + C * k_l; + float m_ = L + C * k_m; + float s_ = L + C * k_s; + + float l = l_ * l_ * l_; + float m = m_ * m_ * m_; + float s = s_ * s_ * s_; + + float ldt = 3 * l_dt * l_ * l_; + float mdt = 3 * m_dt * m_ * m_; + float sdt = 3 * s_dt * s_ * s_; + + float ldt2 = 6 * l_dt * l_dt * l_; + float mdt2 = 6 * m_dt * m_dt * m_; + float sdt2 = 6 * s_dt * s_dt * s_; + + float r = 4.0767416621f * l - 3.3077115913f * m + 0.2309699292f * s - 1; + float r1 = 4.0767416621f * ldt - 3.3077115913f * mdt + 0.2309699292f * sdt; + float r2 = 4.0767416621f * ldt2 - 3.3077115913f * mdt2 + 0.2309699292f * sdt2; + + float u_r = r1 / (r1 * r1 - 0.5f * r * r2); + float t_r = -r * u_r; + + float g = -1.2684380046f * l + 2.6097574011f * m - 0.3413193965f * s - 1; + float g1 = -1.2684380046f * ldt + 2.6097574011f * mdt - 0.3413193965f * sdt; + float g2 = -1.2684380046f * ldt2 + 2.6097574011f * mdt2 - 0.3413193965f * sdt2; + + float u_g = g1 / (g1 * g1 - 0.5f * g * g2); + float t_g = -g * u_g; + + float b = -0.0041960863f * l - 0.7034186147f * m + 1.7076147010f * s - 1; + float b1 = -0.0041960863f * ldt - 0.7034186147f * mdt + 1.7076147010f * sdt; + float b2 = -0.0041960863f * ldt2 - 0.7034186147f * mdt2 + 1.7076147010f * sdt2; + + float u_b = b1 / (b1 * b1 - 0.5f * b * b2); + float t_b = -b * u_b; + + t_r = u_r >= 0.f ? t_r : FLT_MAX; + t_g = u_g >= 0.f ? t_g : FLT_MAX; + t_b = u_b >= 0.f ? t_b : FLT_MAX; + + t += fmin(t_r, fmin(t_g, t_b)); + } + } + } + + return t; +} + +float clamp(float x, float min, float max) +{ + if (x < min) + return min; + if (x > max) + return max; + + return x; +} + +float sgn(float x) +{ + return (float)(0.f < x) - (float)(x < 0.f); +} + +RGB gamut_clip_preserve_chroma(RGB rgb) +{ + if (rgb.r < 1 && rgb.g < 1 && rgb.b < 1 && rgb.r > 0 && rgb.g > 0 && rgb.b > 0) + return rgb; + + Lab lab = linear_displayP3_to_oklab(rgb); + + float L = lab.L; + float eps = 0.00001f; + float C = fmax(eps, sqrtf(lab.a * lab.a + lab.b * lab.b)); + float a_ = lab.a / C; + float b_ = lab.b / C; + + float L0 = clamp(L, 0, 1); + + float t = find_gamut_intersection(a_, b_, L, C, L0); + float L_clipped = L0 * (1 - t) + t * L; + float C_clipped = t * C; + + return oklab_to_linear_displayP3({ L_clipped, C_clipped * a_, C_clipped * b_ }); +} + +RGB gamut_clip_project_to_0_5(RGB rgb) +{ + if (rgb.r < 1 && rgb.g < 1 && rgb.b < 1 && rgb.r > 0 && rgb.g > 0 && rgb.b > 0) + return rgb; + + Lab lab = linear_displayP3_to_oklab(rgb); + + float L = lab.L; + float eps = 0.00001f; + float C = fmax(eps, sqrtf(lab.a * lab.a + lab.b * lab.b)); + float a_ = lab.a / C; + float b_ = lab.b / C; + + float L0 = 0.5; + + float t = find_gamut_intersection(a_, b_, L, C, L0); + float L_clipped = L0 * (1 - t) + t * L; + float C_clipped = t * C; + + return oklab_to_linear_displayP3({ L_clipped, C_clipped * a_, C_clipped * b_ }); +} + +RGB gamut_clip_project_to_L_cusp(RGB rgb) +{ + if (rgb.r < 1 && rgb.g < 1 && rgb.b < 1 && rgb.r > 0 && rgb.g > 0 && rgb.b > 0) + return rgb; + + Lab lab = linear_displayP3_to_oklab(rgb); + + float L = lab.L; + float eps = 0.00001f; + float C = fmax(eps, sqrtf(lab.a * lab.a + lab.b * lab.b)); + float a_ = lab.a / C; + float b_ = lab.b / C; + + // The cusp is computed here and in find_gamut_intersection, an optimized solution would only compute it once. + LC cusp = find_cusp(a_, b_); + + float L0 = cusp.L; + + float t = find_gamut_intersection(a_, b_, L, C, L0); + + float L_clipped = L0 * (1 - t) + t * L; + float C_clipped = t * C; + + return oklab_to_linear_displayP3({ L_clipped, C_clipped * a_, C_clipped * b_ }); +} + +RGB gamut_clip_adaptive_L0_0_5(RGB rgb, float alpha = 0.05f) +{ + if (rgb.r < 1 && rgb.g < 1 && rgb.b < 1 && rgb.r > 0 && rgb.g > 0 && rgb.b > 0) + return rgb; + + Lab lab = linear_displayP3_to_oklab(rgb); + + float L = lab.L; + float eps = 0.00001f; + float C = fmax(eps, sqrtf(lab.a * lab.a + lab.b * lab.b)); + float a_ = lab.a / C; + float b_ = lab.b / C; + + float Ld = L - 0.5f; + float e1 = 0.5f + fabs(Ld) + alpha * C; + float L0 = 0.5f*(1.f + sgn(Ld)*(e1 - sqrtf(e1*e1 - 2.f *fabs(Ld)))); + + float t = find_gamut_intersection(a_, b_, L, C, L0); + float L_clipped = L0 * (1.f - t) + t * L; + float C_clipped = t * C; + + return oklab_to_linear_displayP3({ L_clipped, C_clipped * a_, C_clipped * b_ }); +} + +RGB gamut_clip_adaptive_L0_L_cusp(RGB rgb, float alpha = 0.05f) +{ + if (rgb.r < 1 && rgb.g < 1 && rgb.b < 1 && rgb.r > 0 && rgb.g > 0 && rgb.b > 0) + return rgb; + + Lab lab = linear_displayP3_to_oklab(rgb); + + float L = lab.L; + float eps = 0.00001f; + float C = fmax(eps, sqrtf(lab.a * lab.a + lab.b * lab.b)); + float a_ = lab.a / C; + float b_ = lab.b / C; + + // The cusp is computed here and in find_gamut_intersection, an optimized solution would only compute it once. + LC cusp = find_cusp(a_, b_); + + float Ld = L - cusp.L; + float k = 2.f * (Ld > 0 ? 1.f - cusp.L : cusp.L); + + float e1 = 0.5f*k + fabs(Ld) + alpha * C/k; + float L0 = cusp.L + 0.5f * (sgn(Ld) * (e1 - sqrtf(e1 * e1 - 2.f * k * fabs(Ld)))); + + float t = find_gamut_intersection(a_, b_, L, C, L0); + float L_clipped = L0 * (1.f - t) + t * L; + float C_clipped = t * C; + + return oklab_to_linear_displayP3({ L_clipped, C_clipped * a_, C_clipped * b_ }); +} + +} +} +} diff --git a/python/lsst/cpputils/_cpputils.cc b/python/lsst/cpputils/_cpputils.cc index 84f2231..d704501 100644 --- a/python/lsst/cpputils/_cpputils.cc +++ b/python/lsst/cpputils/_cpputils.cc @@ -28,6 +28,7 @@ namespace cpputils { void wrapBacktrace(python::WrapperCollection & wrappers); void wrapDemangle(python::WrapperCollection & wrappers); +void wrapFixGamut(python::WrapperCollection & wrappers); PYBIND11_MODULE(_cpputils, mod) { python::WrapperCollection wrappers(mod, "_cpputils"); @@ -37,6 +38,7 @@ PYBIND11_MODULE(_cpputils, mod) { wrappers.collectSubmodule(std::move(backtraceWrappers)); } wrapDemangle(wrappers); + wrapFixGamut(wrappers); wrappers.finish(); } diff --git a/python/lsst/cpputils/_gamutFixer.cc b/python/lsst/cpputils/_gamutFixer.cc new file mode 100644 index 0000000..d1ea727 --- /dev/null +++ b/python/lsst/cpputils/_gamutFixer.cc @@ -0,0 +1,76 @@ +/* + * Developed for the LSST Data Management System. + * This product includes software developed by the LSST Project + * (https://www.lsst.org). + * See the COPYRIGHT file at the top-level directory of this distribution + * for details of code ownership. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ +#include "pybind11/pybind11.h" +#include "pybind11/numpy.h" +#include "lsst/cpputils/python.h" +#include "lsst/cpputils/_oklabTools.h" + +namespace py = pybind11; + +namespace lsst { +namespace cpputils { + + +py::array_t fixGamutOK(py::array_t & Lab_points) { + py::buffer_info Lab_buffer = Lab_points.request(); + auto Lab_ptr = Lab_points.unchecked<2>(); + py::array_t result(Lab_buffer.shape); + py::buffer_info result_buffer = result.request(); + auto result_ptr = result.mutable_unchecked<2>(); + float alpha = 0.5f; + + for (int pixel_number=0; pixel_number < Lab_buffer.shape[0]; pixel_number++){ + double L = Lab_ptr(pixel_number, 0); + double a = Lab_ptr(pixel_number, 1); + double b = Lab_ptr(pixel_number, 2); + double esp = 0.00001; + float C = std::max(esp, sqrt(a*a + b*b)); + float a_ = a/C; + float b_ = b/C; + + details::LC cusp = details::find_cusp(a_, b_); + float Ld = L - cusp.L; + float k = 2.f * (Ld > 0 ? 1.f - cusp.L : cusp.L); + + float e1 = 0.5f*k + fabs(Ld) + alpha * C/k; + float L0 = cusp.L + 0.5f * (details::sgn(Ld) * (e1 - sqrtf(e1 * e1 - 2.f * k * fabs(Ld)))); + + float t = details::find_gamut_intersection(a_, b_, L, C, L0); + float L_clipped = L0 * (1.f - t) + t * L; + float C_clipped = t * C; + + result_ptr(pixel_number, 0) = L_clipped; + result_ptr(pixel_number, 1) = C_clipped * a_; + result_ptr(pixel_number, 2) = C_clipped * b_; + } + return result; + +} + +void wrapFixGamut(lsst::cpputils::python::WrapperCollection &wrappers) { + wrappers.wrap([](auto &mod) { + mod.def("fixGamutOK", &fixGamutOK,""); + }); +} + +} +} +