Make the HSV pickers keep the same luminance no matter what the saturation is. Makes...

diff --git a/main.cpp b/main.cpp
index 0340cace0075a596855f76aaf72c4fdd1567a20b..3c807a1b7af588fb9b9cffb4a56f734b350d5f75 100644 (file)
--- a/main.cpp
+++ b/main.cpp
@@ -47,9 +47,9 @@ void update_hsv(Effect *lift_gamma_gain_effect, Effect *saturation_effect)
        RGBTriplet gamma(1.0f, 1.0f, 1.0f);
        RGBTriplet gain(1.0f, 1.0f, 1.0f);
 
-       hsv2rgb(lift_theta, lift_rad, lift_v, &lift.r, &lift.g, &lift.b);
-       hsv2rgb(gamma_theta, gamma_rad, gamma_v * 2.0f, &gamma.r, &gamma.g, &gamma.b);
-       hsv2rgb(gain_theta, gain_rad, gain_v * 4.0f, &gain.r, &gain.g, &gain.b);
+       hsv2rgb_normalized(lift_theta, lift_rad, lift_v, &lift.r, &lift.g, &lift.b);
+       hsv2rgb_normalized(gamma_theta, gamma_rad, gamma_v * 2.0f, &gamma.r, &gamma.g, &gamma.b);
+       hsv2rgb_normalized(gain_theta, gain_rad, gain_v * 4.0f, &gain.r, &gain.g, &gain.b);
 
        bool ok = lift_gamma_gain_effect->set_vec3("lift", (float *)&lift);
        ok = ok && lift_gamma_gain_effect->set_vec3("gamma", (float *)&gamma);

diff --git a/util.cpp b/util.cpp
index 08298c7701b9146fcbd76b9330170b458a80f28b..1c47e11787a8c9781d662334430a2220aef47bf0 100644 (file)
--- a/util.cpp
+++ b/util.cpp
@@ -46,6 +46,21 @@ void hsv2rgb(float h, float s, float v, float *r, float *g, float *b)
        *b += m;
 }
 
+void hsv2rgb_normalized(float h, float s, float v, float *r, float *g, float *b)
+{
+       float ref_r, ref_g, ref_b;
+       hsv2rgb(h, s, v, r, g, b);
+       hsv2rgb(h, 0.0f, v, &ref_r, &ref_g, &ref_b);
+       float lum = 0.2126 * *r + 0.7152 * *g + 0.0722 * *b;
+       float ref_lum = 0.2126 * ref_r + 0.7152 * ref_g + 0.0722 * ref_b;
+       if (lum > 1e-3) {
+               float fac = ref_lum / lum;
+               *r *= fac;
+               *g *= fac;
+               *b *= fac;
+       }
+}
+
 std::string read_file(const std::string &filename)
 {
        static char buf[131072];

diff --git a/util.h b/util.h
index da2bf50b1283a1060020c47f33b2e20c50bd65fc..4834bbdf4a86f4dc6048183f6f74d8b1259e3f10 100644 (file)
--- a/util.h
+++ b/util.h
@@ -15,6 +15,10 @@
 // Converts a HSV color to RGB. Assumes h in [0, 2pi> or [-pi, pi>
 void hsv2rgb(float h, float s, float v, float *r, float *g, float *b);
 
+// Converts a HSV color to RGB, but keeps luminance constant
+// (ie. color luminance is as if S=0).
+void hsv2rgb_normalized(float h, float s, float v, float *r, float *g, float *b);
+
 // Column major (same as OpenGL).
 typedef double Matrix3x3[9];