Update to REC.709, not batshit crazy REC.601

Update to use REC.709 coefficients.

effects/shaders/chromakey.frag

@@ -15,17 +15,24 @@ uniform int mode;
  
 float rgb2y (vec3 c) { 
 	/*a utility function to convert colors in RGB into YCbCr*/ 
-	return (0.299*c.r + 0.587*c.g + 0.114*c.b);
+
+// This isn’t colour managed and is a huge mess, but in the
+// short term, using correct weights will give significantly
+// more ideal results. The correct weights for REC.709 are
+// 0.2126 R, 0.7152 G, and 0.722 B. Easy change.
+// The coefficients for YCbCr are calculated off of the
+// REC.709 values.
+	return (0.2126*c.r + 0.7152*c.g + 0.0.722*c.b);
 } 
  
 float rgb2cb (vec3 c) { 
 	/*a utility function to convert colors in RGB into YCbCr*/ 
-	return (0.5 + -0.168736*c.r - 0.331264*c.g + 0.5*c.b);
+	return (0.5 + -0.1145721061*c.r - 0.3854278939*c.g + 0.5*c.b);
 } 
  
 float rgb2cr (vec3 c) { 
 	/*a utility function to convert colors in RGB into YCbCr*/ 
-	return (0.5 + 0.5*c.r - 0.418688*c.g - 0.081312*c.b);
+	return (0.5 + 0.5*c.r - 0.4541529083*c.g - 0.0458470917*c.b);
 } 
  
 float colorclose(float Cb_p,float Cr_p,float Cb_key,float Cr_key,float tola,float tolb) { 
@@ -62,4 +69,4 @@ void main(void) {
 	}
 	
 	gl_FragColor = texture_color;
-}
+}