Color-separated Saturation

include/effects/Saturation.h

@@ -64,15 +64,21 @@ namespace openshot
 		void init_effect_details();
 
 	public:
-		Keyframe saturation;	///< The color saturation: 0.0 = black and white, 1.0 = normal, 2.0 = double saturation
+		Keyframe saturation;	///< Overall color saturation: 0.0 = greyscale, 1.0 = normal, 2.0 = double saturation
+		Keyframe saturation_R;	///< Red color saturation
+		Keyframe saturation_G;	///< Green color saturation
+		Keyframe saturation_B;	///< Blue color saturation
 
 		/// Blank constructor, useful when using Json to load the effect properties
 		Saturation();
 
-		/// Default constructor, which takes 1 curve, to adjust the color saturation over time.
+		/// Default constructor, which takes four curves (one common curve and one curve per color), to adjust the color saturation over time.
 		///
-		/// @param new_saturation The curve to adjust the saturation of the frame's image (0.0 = black and white, 1.0 = normal, 2.0 = double saturation)
-		Saturation(Keyframe new_saturation);
+		/// @param saturation The curve to adjust the saturation of the frame's image (0.0 = greyscale, 1.0 = normal, 2.0 = double saturation)
+		/// @param saturation_R The curve to adjust red saturation of the frame's image (0.0 = greyscale, 1.0 = normal, 2.0 = double saturation)
+		/// @param saturation_G The curve to adjust green saturation of the frame's image (0.0 = greyscale, 1.0 = normal, 2.0 = double saturation)
+		/// @param saturation_B The curve to adjust blue saturation of the frame's image (0.0 = greyscale, 1.0 = normal, 2.0 = double saturation)
+		Saturation(Keyframe saturation, Keyframe saturation_R, Keyframe saturation_G, Keyframe saturation_B);
 
 		/// @brief This method is required for all derived classes of EffectBase, and returns a
 		/// modified openshot::Frame object

src/effects/Saturation.cpp

@@ -33,13 +33,14 @@
 using namespace openshot;
 
 /// Blank constructor, useful when using Json to load the effect properties
-Saturation::Saturation() : saturation(1.0) {
+Saturation::Saturation() : saturation(1.0), saturation_R(1.0), saturation_G(1.0), saturation_B(1.0) {
 	// Init effect properties
 	init_effect_details();
 }
 
 // Default constructor
-Saturation::Saturation(Keyframe new_saturation) : saturation(new_saturation)
+Saturation::Saturation(Keyframe saturation, Keyframe saturation_R, Keyframe saturation_G, Keyframe saturation_B) :
+		saturation(saturation), saturation_R(saturation_R), saturation_G(saturation_G), saturation_B(saturation_B)
 {
 	// Init effect properties
 	init_effect_details();
@@ -73,6 +74,9 @@ std::shared_ptr<Frame> Saturation::GetFrame(std::shared_ptr<Frame> frame, int64_
 
 	// Get keyframe values for this frame
 	float saturation_value = saturation.GetValue(frame_number);
+	float saturation_value_R = saturation_R.GetValue(frame_number);
+	float saturation_value_G = saturation_G.GetValue(frame_number);
+	float saturation_value_B = saturation_B.GetValue(frame_number);
 
 	// Constants used for color saturation formula
 	const double pR = .299;
@@ -90,15 +94,66 @@ std::shared_ptr<Frame> Saturation::GetFrame(std::shared_ptr<Frame> frame, int64_
 		int G = pixels[pixel * 4 + 1];
 		int B = pixels[pixel * 4 + 2];
 
+		/*
+		 * Common saturation adjustment
+		 */
+
 		// Calculate the saturation multiplier
 		double p = sqrt( (R * R * pR) +
-		                 (G * G * pG) +
-		                 (B * B * pB) );
-
-		// Apply adjusted and constrained saturation
-		pixels[pixel * 4]     = constrain(p + (R - p) * saturation_value);
-		pixels[pixel * 4 + 1] = constrain(p + (G - p) * saturation_value);
-		pixels[pixel * 4 + 2] = constrain(p + (B - p) * saturation_value);
+						 (G * G * pG) +
+						 (B * B * pB) );
+
+		// Adjust the saturation
+		R = p + (R - p) * saturation_value;
+		G = p + (G - p) * saturation_value;
+		B = p + (B - p) * saturation_value;
+
+		// Constrain the value from 0 to 255
+		R = constrain(R);
+		G = constrain(G);
+		B = constrain(B);
+
+		/*
+		 * Color-separated saturation adjustment
+		 *
+		 * Splitting each of the three subpixels (R, G and B) into three distincs sub-subpixels (R, G and B in turn)
+		 * which in their optical sum reproduce the original subpixel's color OR produce white light in the brightness
+		 * of the original subpixel (dependening on the color channel's slider value).
+		 */
+
+		// Compute the brightness ("saturation multiplier") of the replaced subpixels
+		// Actually mathematical no-ops mostly, verbosity is kept just for clarification
+		const double p_r = sqrt(R * R * pR);
+		const double p_g = sqrt(G * G * pG);
+		const double p_b = sqrt(B * B * pB);
+
+		// Adjust the saturation
+		const int Rr = p_r + (R - p_r) * saturation_value_R;
+		const int Gr = p_r + (0 - p_r) * saturation_value_R;
+		const int Br = p_r + (0 - p_r) * saturation_value_R;
+
+		const int Rg = p_g + (0 - p_g) * saturation_value_G;
+		const int Gg = p_g + (G - p_g) * saturation_value_G;
+		const int Bg = p_g + (0 - p_g) * saturation_value_G;
+
+		const int Rb = p_b + (0 - p_b) * saturation_value_B;
+		const int Gb = p_b + (0 - p_b) * saturation_value_B;
+		const int Bb = p_b + (B - p_b) * saturation_value_B;
+
+		// Recombine brightness of sub-subpixels (Rx, Gx and Bx) into sub-pixels (R, G and B) again
+		R = Rr + Rg + Rb;
+		G = Gr + Gg + Gb;
+		B = Br + Bg + Bb;
+
+		// Constrain the value from 0 to 255
+		R = constrain(R);
+		G = constrain(G);
+		B = constrain(B);
+
+		// Set all pixels to new value
+		pixels[pixel * 4]     = R;
+		pixels[pixel * 4 + 1] = G;
+		pixels[pixel * 4 + 2] = B;
 	}
 
 	// return the modified frame
@@ -119,6 +174,9 @@ Json::Value Saturation::JsonValue() const {
 	Json::Value root = EffectBase::JsonValue(); // get parent properties
 	root["type"] = info.class_name;
 	root["saturation"] = saturation.JsonValue();
+	root["saturation_R"] = saturation_R.JsonValue();
+	root["saturation_G"] = saturation_G.JsonValue();
+	root["saturation_B"] = saturation_B.JsonValue();
 
 	// return JsonValue
 	return root;
@@ -150,6 +208,12 @@ void Saturation::SetJsonValue(const Json::Value root) {
 	// Set data from Json (if key is found)
 	if (!root["saturation"].isNull())
 		saturation.SetJsonValue(root["saturation"]);
+	if (!root["saturation_R"].isNull())
+		saturation_R.SetJsonValue(root["saturation_R"]);
+	if (!root["saturation_G"].isNull())
+		saturation_G.SetJsonValue(root["saturation_G"]);
+	if (!root["saturation_B"].isNull())
+		saturation_B.SetJsonValue(root["saturation_B"]);
 }
 
 // Get all properties for a specific frame
@@ -166,6 +230,9 @@ std::string Saturation::PropertiesJSON(int64_t requested_frame) const {
 
 	// Keyframes
 	root["saturation"] = add_property_json("Saturation", saturation.GetValue(requested_frame), "float", "", &saturation, 0.0, 4.0, false, requested_frame);
+	root["saturation_R"] = add_property_json("Saturation (Red)", saturation_R.GetValue(requested_frame), "float", "", &saturation_R, 0.0, 4.0, false, requested_frame);
+	root["saturation_G"] = add_property_json("Saturation (Green)", saturation_G.GetValue(requested_frame), "float", "", &saturation_G, 0.0, 4.0, false, requested_frame);
+	root["saturation_B"] = add_property_json("Saturation (Blue)", saturation_B.GetValue(requested_frame), "float", "", &saturation_B, 0.0, 4.0, false, requested_frame);
 
 	// Return formatted string
 	return root.toStyledString();