hyperion.ng/libsrc/utils/HslTransform.cpp
Funatiq 45dff6d1d3 Reduce saturation in backlight (#651)
Former-commit-id: c2c4fd6f957c3623e03c37393cf3c03a7a27dc1e
2016-05-24 22:15:39 +02:00

176 lines
3.6 KiB
C++

#include <algorithm>
#include <cmath>
#include <utils/HslTransform.h>
HslTransform::HslTransform() :
_saturationGain(1.0),
_luminanceGain(1.0),
_luminanceMinimum(0.0)
{
}
HslTransform::HslTransform(double saturationGain, double luminanceGain, double luminanceMinimum) :
_saturationGain(saturationGain),
_luminanceGain(luminanceGain),
_luminanceMinimum(luminanceMinimum)
{
}
HslTransform::~HslTransform()
{
}
void HslTransform::setSaturationGain(double saturationGain)
{
_saturationGain = saturationGain;
}
double HslTransform::getSaturationGain() const
{
return _saturationGain;
}
void HslTransform::setLuminanceGain(double luminanceGain)
{
_luminanceGain = luminanceGain;
}
double HslTransform::getLuminanceGain() const
{
return _luminanceGain;
}
void HslTransform::setLuminanceMinimum(double luminanceMinimum)
{
_luminanceMinimum = luminanceMinimum;
}
double HslTransform::getLuminanceMinimum() const
{
return _luminanceMinimum;
}
void HslTransform::transform(uint8_t & red, uint8_t & green, uint8_t & blue) const
{
if (_saturationGain != 1.0 || _luminanceGain != 1.0 || _luminanceMinimum != 0.0)
{
uint16_t hue;
float saturation, luminance;
rgb2hsl(red, green, blue, hue, saturation, luminance);
float s = saturation * _saturationGain;
if (s > 1.0f)
saturation = 1.0f;
else
saturation = s;
float l = luminance * _luminanceGain;
if (l < _luminanceMinimum)
{
saturation *= l/_luminanceMinimum;
l = _luminanceMinimum;
}
if (l > 1.0f)
luminance = 1.0f;
else
luminance = l;
hsl2rgb(hue, saturation, luminance, red, green, blue);
}
}
void HslTransform::rgb2hsl(uint8_t red, uint8_t green, uint8_t blue, uint16_t & hue, float & saturation, float & luminance)
{
float r = red / 255.0f;
float g = green / 255.0f;
float b = blue / 255.0f;
float rgbMin = r < g ? (r < b ? r : b) : (g < b ? g : b);
float rgbMax = r > g ? (r > b ? r : b) : (g > b ? g : b);
float diff = rgbMax - rgbMin;
//luminance
luminance = (rgbMin + rgbMax) / 2.0f;
if (diff == 0.0f) {
saturation = 0.0f;
hue = 0;
return;
}
//saturation
if (luminance < 0.5f)
saturation = diff / (rgbMin + rgbMax);
else
saturation = diff / (2.0f - rgbMin - rgbMax);
if (rgbMax == r)
{
// start from 360 to be sure that we won't assign a negative number to the unsigned hue value
hue = 360 + 60 * (g - b) / (rgbMax - rgbMin);
if (hue > 359)
hue -= 360;
}
else if (rgbMax == g)
{
hue = 120 + 60 * (b - r) / (rgbMax - rgbMin);
}
else
{
hue = 240 + 60 * (r - g) / (rgbMax - rgbMin);
}
}
void HslTransform::hsl2rgb(uint16_t hue, float saturation, float luminance, uint8_t & red, uint8_t & green, uint8_t & blue)
{
if (saturation == 0.0f){
red = (uint8_t)(luminance * 255.0f);
green = (uint8_t)(luminance * 255.0f);
blue = (uint8_t)(luminance * 255.0f);
return;
}
float q;
if (luminance < 0.5f)
q = luminance * (1.0f + saturation);
else
q = (luminance + saturation) - (luminance * saturation);
float p = (2.0f * luminance) - q;
float h = hue / 360.0f;
float t[3];
t[0] = h + (1.0f / 3.0f);
t[1] = h;
t[2] = h - (1.0f / 3.0f);
for (int i = 0; i < 3; i++) {
if (t[i] < 0.0f)
t[i] += 1.0f;
if (t[i] > 1.0f)
t[i] -= 1.0f;
}
float out[3];
for (int i = 0; i < 3; i++) {
if (t[i] * 6.0f < 1.0f)
out[i] = p + (q - p) * 6.0f * t[i];
else if (t[i] * 2.0f < 1.0f)
out[i] = q;
else if (t[i] * 3.0f < 2.0f)
out[i] = p + (q - p) * ((2.0f / 3.0f) - t[i]) * 6.0f;
else out[i] = p;
}
//convert back to 0...255 range
red = (uint8_t)(out[0] * 255.0f);
green = (uint8_t)(out[1] * 255.0f);
blue = (uint8_t)(out[2] * 255.0f);
}