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/* Shader for conversion of RGB textures into Grayscale textures.
* Uses standard formula for conversion:
* (w)2006 by Mario Kleiner. Licensed under MIT license.
*/
#extension GL_ARB_texture_rectangle : enable
const mat3 rgb2ycbcrMatrix = mat3(0.299, -0.168736, 0.5, 0.587, -0.331264, -0.418688, 0.114, 0.5, -0.081312);
const vec3 rgb2y = vec3(0.299, 0.587, 0.114);
const vec3 rgb2cb = vec3(-0.168736, -0.331264, 0.5);
const vec3 rgb2cr = vec3(0.5, -0.418688, -0.081312);
uniform sampler2DRect Image;
uniform vec4 Roi;
uniform vec4 ColorRoi;
uniform float GrayThreshold;
void main()
{
float accept = 0.0;
vec3 ycbcr;
vec4 incolor = texture2DRect(Image, gl_TexCoord[0].st);
ycbcr.r = dot(rgb2y, incolor.rgb);
ycbcr.g = dot(rgb2cb, incolor.rgb);
ycbcr.b = dot(rgb2cr, incolor.rgb);
ycbcr+= vec3(0.0, 0.5, 0.5);
accept = step(0.00, ycbcr.r) * step(ycbcr.r, GrayThreshold);
accept = accept * step(ColorRoi.x, ycbcr.g) * step(ycbcr.g, ColorRoi.y);
accept = accept * step(ColorRoi.z, ycbcr.b) * step(ycbcr.b, ColorRoi.w);
gl_FragColor.a = accept;
gl_FragColor.rgb = incolor.rgb * (0.5 + accept);
}
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