Merge pull request #427 from ferdnyc/optimized-hue

Hue: Optimize and parallelize

Author: jonoomph

src/effects/Hue.cpp

@@ -66,36 +66,35 @@ std::shared_ptr<Frame> Hue::GetFrame(std::shared_ptr<Frame> frame, int64_t frame
 	// Get the frame's image
 	std::shared_ptr<QImage> frame_image = frame->GetImage();
 
+	int pixel_count = frame_image->width() * frame_image->height();
+
 	// Get the current hue percentage shift amount, and convert to degrees
 	double degrees = 360.0 * hue.GetValue(frame_number);
 	float cosA = cos(degrees*3.14159265f/180);
 	float sinA = sin(degrees*3.14159265f/180);
 
 	// Calculate a rotation matrix for the RGB colorspace (based on the current hue shift keyframe value)
-	float matrix[3][3] = {{cosA + (1.0f - cosA) / 3.0f, 1.0f/3.0f * (1.0f - cosA) - sqrtf(1.0f/3.0f) * sinA, 1.0f/3.0f * (1.0f - cosA) + sqrtf(1.0f/3.0f) * sinA},
-						  {1.0f/3.0f * (1.0f - cosA) + sqrtf(1.0f/3.0f) * sinA, cosA + 1.0f/3.0f*(1.0f - cosA), 1.0f/3.0f * (1.0f - cosA) - sqrtf(1.0f/3.0f) * sinA},
-						  {1.0f/3.0f * (1.0f - cosA) - sqrtf(1.0f/3.0f) * sinA, 1.0f/3.0f * (1.0f - cosA) + sqrtf(1.0f/3.0f) * sinA, cosA + 1.0f/3.0f * (1.0f - cosA)}};
+	float matrix[3] = {
+		cosA + (1.0f - cosA) / 3.0f,
+		1.0f/3.0f * (1.0f - cosA) - sqrtf(1.0f/3.0f) * sinA,
+		1.0f/3.0f * (1.0f - cosA) + sqrtf(1.0f/3.0f) * sinA
+	};
 
 	// Loop through pixels
 	unsigned char *pixels = (unsigned char *) frame_image->bits();
-	for (int pixel = 0, byte_index=0; pixel < frame_image->width() * frame_image->height(); pixel++, byte_index+=4)
+
+	#pragma omp parallel for shared (pixels)
+	for (int pixel = 0; pixel < pixel_count; ++pixel)
 	{
-		// Get the RGB values from the pixel
-		int R = pixels[byte_index];
-		int G = pixels[byte_index + 1];
-		int B = pixels[byte_index + 2];
-		int A = pixels[byte_index + 3];
+		// Get the RGB values from the pixel (ignore the alpha channel)
+		int R = pixels[pixel * 4];
+		int G = pixels[pixel * 4 + 1];
+		int B = pixels[pixel * 4 + 2];
 
 		// Multiply each color by the hue rotation matrix
-		float rx = constrain(R * matrix[0][0] + G * matrix[0][1] + B * matrix[0][2]);
-		float gx = constrain(R * matrix[1][0] + G * matrix[1][1] + B * matrix[1][2]);
-		float bx = constrain(R * matrix[2][0] + G * matrix[2][1] + B * matrix[2][2]);
-
-		// Set all pixels to new value
-		pixels[byte_index] = rx;
-		pixels[byte_index + 1] = gx;
-		pixels[byte_index + 2] = bx;
-		pixels[byte_index + 3] = A; // leave the alpha value alone
+		pixels[pixel * 4] = constrain(R * matrix[0] + G * matrix[1] + B * matrix[2]);
+		pixels[pixel * 4 + 1] = constrain(R * matrix[2] + G * matrix[0] + B * matrix[1]);
+		pixels[pixel * 4 + 2] = constrain(R * matrix[1] + G * matrix[2] + B * matrix[0]);
 	}
 
 	// return the modified frame