Saturation & Brightness/Value Gain using Oklab color space (#1477)

* Imported Oklab reference implementation

* Add Okhsv conversions

* Fixed formatting error

* Add saturation and value gain to schemas

* Add english translation for saturation, value gain

* Created OkhsvTransform

* Make OkhsvTransform configurable

* Apply OkhvsTransform

* Clamped values during transform

* Precalculate isIdentity in OkhsvTransform

* Skip OkhsvTransform if it is the identity function

* Added changelog message

* Allow for full desaturation

* Imported recommended changes by LordGrey

* Fixed typo in constant

* Fixed anti-pattern in ok_color.h

* Correct indentions

* Correct remote-control

* Limited maximum gain settings to practical range

* Renane valueGain to brightnessGain for clarity and understanding

Co-authored-by: LordGrey <lordgrey.emmel@gmail.com>

libsrc/utils/CMakeLists.txt

@@ -19,6 +19,8 @@ SET(CURRENT_SOURCE_DIR ${CMAKE_SOURCE_DIR}/libsrc/utils)
 
 FILE ( GLOB_RECURSE Utils_SOURCES "${CURRENT_HEADER_DIR}/*.h"  "${CURRENT_SOURCE_DIR}/*.h"  "${CURRENT_SOURCE_DIR}/*.cpp" )
 
+list(APPEND Utils_SOURCES "${CMAKE_SOURCE_DIR}/dependencies/include/oklab/ok_color.h")
+
 if ( NOT ENABLE_PROFILER )
 	LIST ( REMOVE_ITEM Utils_SOURCES ${CURRENT_HEADER_DIR}/Profiler.h ${CURRENT_SOURCE_DIR}/Profiler.cpp )
 endif()

libsrc/utils/ColorSys.cpp

@@ -1,6 +1,7 @@
 #include <utils/ColorSys.h>
 
 #include <QColor>
+#include <oklab/ok_color.h>
 
 inline uint8_t clamp(int x)
 {
@@ -56,3 +57,22 @@ void ColorSys::yuv2rgb(uint8_t y, uint8_t u, uint8_t v, uint8_t &r, uint8_t &g,
 	g = clamp((298 * c - 100 * d - 208 * e + 128) >> 8);
 	b = clamp((298 * c + 516 * d + 128) >> 8);
 }
+
+void ColorSys::rgb2okhsv(uint8_t red, uint8_t green, uint8_t blue, double & hue, double & saturation, double & value)
+{
+	ok_color::HSV color = ok_color::srgb_to_okhsv({ static_cast<float>(red)   / 255.F,
+													static_cast<float>(green) / 255.F,
+													static_cast<float>(blue)  / 255.F
+	});
+	hue = color.h;
+	saturation = color.s;
+	value = color.v;
+}
+
+void ColorSys::okhsv2rgb(double hue, double saturation, double value, uint8_t & red, uint8_t & green, uint8_t & blue)
+{
+	ok_color::RGB color = ok_color::okhsv_to_srgb({ static_cast<float>(hue), static_cast<float>(saturation), static_cast<float>(value) });
+	red = static_cast<uint8_t>(std::lround(color.r * 255));
+	green = static_cast<uint8_t>(std::lround(color.g * 255));
+	blue = static_cast<uint8_t>(std::lround(color.b * 255));
+}

libsrc/utils/OkhsvTransform.cpp

@@ -0,0 +1,69 @@
+#include <algorithm>
+
+#include <utils/OkhsvTransform.h>
+#include <utils/ColorSys.h>
+
+/// Clamps between 0.f and 1.f. Should generally be branchless
+double clamp(double value)
+{
+	return std::max(0.0, std::min(value, 1.0));
+}
+
+OkhsvTransform::OkhsvTransform()
+{
+	_saturationGain = 1.0;
+	_brightnessGain = 1.0;
+	_isIdentity = true;
+}
+
+OkhsvTransform::OkhsvTransform(double saturationGain, double brightnessGain)
+{
+	_saturationGain = saturationGain;
+	_brightnessGain = brightnessGain;
+	updateIsIdentity();
+}
+
+double OkhsvTransform::getSaturationGain() const
+{
+	return _saturationGain;
+}
+
+void OkhsvTransform::setSaturationGain(double saturationGain)
+{
+	_saturationGain = saturationGain;
+	updateIsIdentity();
+}
+
+double OkhsvTransform::getBrightnessGain() const
+{
+	return _brightnessGain;
+}
+
+void OkhsvTransform::setBrightnessGain(double brightnessGain)
+{
+	_brightnessGain= brightnessGain;
+	updateIsIdentity();
+}
+
+bool OkhsvTransform::isIdentity() const
+{
+	return _isIdentity;
+}
+
+void OkhsvTransform::transform(uint8_t & red, uint8_t & green, uint8_t & blue) const
+{
+	double hue;
+	double saturation;
+	double brightness;
+	ColorSys::rgb2okhsv(red, green, blue, hue, saturation, brightness);
+
+	saturation = clamp(saturation * _saturationGain);
+	brightness = clamp(brightness * _brightnessGain);
+
+	ColorSys::okhsv2rgb(hue, saturation, brightness, red, green, blue);
+}
+
+void OkhsvTransform::updateIsIdentity()
+{
+	_isIdentity = _saturationGain == 1.0 && _brightnessGain == 1.0;
+}