fix(image): color drift on copy&paste / save&load

Author: Tom94

include/tev/Common.h

@@ -600,6 +600,10 @@ inline float toSRGB(float val, float gamma = 2.4f) {
     }
 }
 
+inline nanogui::Vector3f toSRGB(nanogui::Vector3f val, float gamma = 2.4f) {
+    return {toSRGB(val.x(), gamma), toSRGB(val.y(), gamma), toSRGB(val.z(), gamma)};
+}
+
 inline float toLinear(float val, float gamma = 2.4f) {
     static constexpr float a = 0.055f;
     static constexpr float threshold = 0.04045f;
@@ -612,6 +616,16 @@ inline float toLinear(float val, float gamma = 2.4f) {
     }
 }
 
+inline nanogui::Vector3f toLinear(nanogui::Vector3f val, float gamma = 2.4f) {
+    return {toLinear(val.x(), gamma), toLinear(val.y(), gamma), toLinear(val.z(), gamma)};
+}
+
+inline float applyGamma(float val, float gamma) { return std::copysign(std::pow(std::abs(val), gamma), val); }
+
+inline nanogui::Vector3f applyGamma(nanogui::Vector3f val, float gamma) {
+    return {applyGamma(val.x(), gamma), applyGamma(val.y(), gamma), applyGamma(val.z(), gamma)};
+}
+
 int lastError();
 int lastSocketError();
 std::string errorString(int errorId);
@@ -696,7 +710,7 @@ inline nanogui::Vector3f applyTonemap(nanogui::Vector3f value, float gamma, ETon
     nanogui::Vector3f result;
     switch (tonemap) {
         case ETonemap::Gamma: {
-            result = {std::pow(value.x(), 1 / gamma), std::pow(value.y(), 1 / gamma), std::pow(value.z(), 1 / gamma)};
+            result = applyGamma(value, 1.0f / gamma);
             break;
         }
         case ETonemap::FalseColor: {

src/Image.cpp

@@ -1241,15 +1241,18 @@ Task<HeapArray<uint8_t>> Image::getRgbaLdrImageData(
         rgbaHdrData.size(),
         [&](const size_t i) {
             const size_t start = 4 * i;
-            const Vector3f rgb = applyTonemap(
-                {
-                    applyExposureAndOffset(rgbaHdrData[start + 0], exposure, offset),
-                    applyExposureAndOffset(rgbaHdrData[start + 1], exposure, offset),
-                    applyExposureAndOffset(rgbaHdrData[start + 2], exposure, offset),
-                },
-                gamma,
-                tonemap
-            );
+            const Vector3f rgb = toSRGB(applyGamma(
+                applyTonemap(
+                    {
+                        applyExposureAndOffset(rgbaHdrData[start + 0], exposure, offset),
+                        applyExposureAndOffset(rgbaHdrData[start + 1], exposure, offset),
+                        applyExposureAndOffset(rgbaHdrData[start + 2], exposure, offset),
+                    },
+                    gamma,
+                    tonemap
+                ),
+                2.2f
+            ));
 
             const auto rgba = Vector4f{rgb.x(), rgb.y(), rgb.z(), rgbaHdrData[start + 3]};