Color-separated Saturation

Signed-off-by: Markus KARG <markus@headcrashing.eu>

include/effects/Saturation.h

@@ -65,14 +65,17 @@ namespace openshot
 
 	public:
 		Keyframe saturation;	///< The color saturation: 0.0 = black and white, 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.
 		///
 		/// @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);
+		Saturation(Keyframe new_saturation, Keyframe new_saturation_R, Keyframe new_saturation_G, Keyframe new_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 +33,13 @@
 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 new_saturation, Keyframe new_saturation_R, Keyframe new_saturation_G, Keyframe new_saturation_B) : saturation(new_saturation), saturation_R(new_saturation_R), saturation_G(new_saturation_G), saturation_B(new_saturation_B)
 {
 	// Init effect properties
 	init_effect_details();
@@ -71,6 +71,9 @@ 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
 	double pR = .299;
@@ -87,6 +90,10 @@ std::shared_ptr<Frame> Saturation::GetFrame(std::shared_ptr<Frame> frame, int64_
 		int B = pixels[byte_index + 2];
 		int A = pixels[byte_index + 3];
 
+		/*
+		 * Common saturation adjustment
+		 */
+
 		// Calculate the saturation multiplier
 		double p = sqrt( (R * R * pR) +
 						 (G * G * pG) +
@@ -102,6 +109,58 @@ std::shared_ptr<Frame> Saturation::GetFrame(std::shared_ptr<Frame> frame, int64_
 		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).
+		 */
+
+		// Three subpixels producing either R or white with brightness of R
+		int Rr = R;
+		int Gr = 0;
+		int Br = 0;
+
+		// Three subpixels producing either G or white with brightness of G
+		int Rg = 0;
+		int Gg = G;
+		int Bg = 0;
+
+		// Three subpixels producing either B or white with brightness of B
+		int Rb = 0;
+		int Gb = 0;
+		int Bb = B;
+
+		// 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( (Rr * Rr * pR) + (Gr * Gr * pG) + (Br * Br * pB) );
+		const double p_g = sqrt( (Rg * Rg * pR) + (Gg * Gg * pG) + (Bg * Bg * pB) );
+		const double p_b = sqrt( (Rb * Rb * pR) + (Gb * Gb * pG) + (Bb * Bb * pB) );
+
+		// Adjust the saturation
+		Rr = p_r + (Rr - p_r) * saturation_value_R;
+		Gr = p_r + (Gr - p_r) * saturation_value_R;
+		Br = p_r + (Br - p_r) * saturation_value_R;
+
+		Rg = p_g + (Rg - p_g) * saturation_value_G;
+		Gg = p_g + (Gg - p_g) * saturation_value_G;
+		Bg = p_g + (Bg - p_g) * saturation_value_G;
+
+		Rb = p_b + (Rb - p_b) * saturation_value_B;
+		Gb = p_b + (Gb - p_b) * saturation_value_B;
+		Bb = p_b + (Bb - 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[byte_index] = R;
 		pixels[byte_index + 1] = G;
@@ -127,6 +186,9 @@ Json::Value Saturation::JsonValue() {
 	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;
@@ -170,6 +232,12 @@ void Saturation::SetJsonValue(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
@@ -186,6 +254,9 @@ std::string Saturation::PropertiesJSON(int64_t requested_frame) {
 
 	// 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();