jfjoch_viewer: Add more color modes - white on black and 3 green schemes

common/ColorScale.cpp

@@ -5,6 +5,26 @@
 #include "ColorScale.h"
 #include "JFJochException.h"
 
+static inline float Clamp01(float x) {
+    return (x < 0.0f) ? 0.0f : (x > 1.0f ? 1.0f : x);
+}
+
+// Gamma-mapped green (recommended gamma = 0.7)
+static inline rgb GreenGamma(float f, float gamma = 0.7f) {
+    f = Clamp01(f);
+    const float g = std::pow(f, gamma);
+    const uint8_t G = static_cast<uint8_t>(std::lround(255.0f * g));
+    return {.r = 0, .g = G, .b = 0};
+}
+
+// Asinh-mapped green (recommended k = 8.0)
+static inline rgb GreenAsinh(float f, float k = 8.0f) {
+    f = Clamp01(f);
+    const float g = std::asinh(k * f) / std::asinh(k);
+    const uint8_t G = static_cast<uint8_t>(std::lround(255.0f * g));
+    return {.r = 0, .g = G, .b = 0};
+}
+
 float luminance(rgb input) {
     return 0.2126f * input.r + 0.7152f * input.g + 0.0722f * input.b;
 }
@@ -26,18 +46,43 @@ void ColorScale::CalcLUT() const {
     const std::vector<rgb>* map = nullptr;
     switch (current) {
         case ColorScaleEnum::Viridis: map = &viridis_colormap; break;
-        case ColorScaleEnum::Heat:    map = &heat_colormap; break;
-        case ColorScaleEnum::Indigo:  map = &white_to_indigo_colormap; break;
-        case ColorScaleEnum::BW:      map = &white_to_black_colormap; break;
+        case ColorScaleEnum::Heat: map = &heat_colormap;
+            break;
+        case ColorScaleEnum::Indigo: map = &white_to_indigo_colormap;
+            break;
+        case ColorScaleEnum::BW: map = &white_to_black_colormap;
+            break;
+        case ColorScaleEnum::WB: map = &black_to_white_colormap;
+            break;
+        case ColorScaleEnum::Green1:
+        case ColorScaleEnum::Green2:
+            map = nullptr;
+            break; // handled below
+        case ColorScaleEnum::Green3:
+            map = &green_colormap;
+            break;
         default:
             throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
                                   "Color scale unknown");
     }
 
-    for (size_t i = 0; i < kLutSize; ++i) {
-        const float f = static_cast<float>(i) / static_cast<float>(kLutSize - 1);
-        lut_[i] = Apply(f, *map);
+    if (current == ColorScaleEnum::Green1) {
+        for (size_t i = 0; i < kLutSize; ++i) {
+            const float f = static_cast<float>(i) / static_cast<float>(kLutSize - 1);
+            lut_[i] = GreenGamma(f, 0.7f);
+        }
+    } else if (current == ColorScaleEnum::Green2) {
+        for (size_t i = 0; i < kLutSize; ++i) {
+            const float f = static_cast<float>(i) / static_cast<float>(kLutSize - 1);
+            lut_[i] = GreenAsinh(f, 8.0f);
+        }
+    } else {
+        for (size_t i = 0; i < kLutSize; ++i) {
+            const float f = static_cast<float>(i) / static_cast<float>(kLutSize - 1);
+            lut_[i] = Apply(f, *map);
+        }
     }
+
 }
 
 rgb ColorScale::Apply(float input, const std::vector<rgb> &map) {