Fix preview color

data/debayer.frag

@@ -22,7 +22,7 @@ void main() {
 
 	// Assume BGGR for now. Currently this just takes 3 of the four samples
 	// for each pixel, there's room here to do some better debayering.
-	vec3 color = vec3(samples.w, (samples.y + samples.w) / 2.0, samples.x);
+	vec3 color = vec3(samples.w, (samples.y + samples.z) / 2.0, samples.x);
 
 	// Fast SRGB estimate. See https://mimosa-pudica.net/fast-gamma/
 	vec3 srgb_color = (vec3(1.138) * inversesqrt(color) - vec3(0.138)) * color;