SAMPLE: QameraWaffleMatrix.qtzThis kernel desaturates the image and inverts it. Very useful as pre-filter for msBlackMergeAlphaFromGrey.

kernel vec4 msBlackInvertRGBLeaveAlpha(sampler input_image)
{
vec4 pixel = sample(input_image, samplerCoord(input_image));
float average = 1.0-clamp((pixel.x+ pixel.y+ pixel.z)/3.0,0.0,1.0);
pixel.r = average;
pixel.g = average;
pixel.b = average;
return pixel;
}

Labels: chroma, color

SAMPLE: QameraYUVMunge.qtzThis kernel distorts the color in the image using two source image "maps". Each image map is evaluated as a greyscale value. This results in an average brightness from 0.0 ... 1.0. Using 0.5 as the center, the source pixel is adjusted in the U and V color axes by the displacements from the maps. The effect is blended back into the source pixel according to amount_normal.

kernel vec4 msBlackColorDisplaceYUV(sampler image, sampler distort_u_map, sampler distort_v_map, float amount_normal)
{
float input_amount = clamp(amount_normal,0.0,1.0);
float inverse_amount = 1.0-input_amount;
const vec3 rgb_y = vec3(0.257, 0.504, 0.098);
const vec3 rgb_u = vec3(-0.148, -0.291, 0.439);
const vec3 rgb_v = vec3(0.439, -0.368, -0.071);
const vec3 yuv_r = vec3(1.0000, 0.0000, 1.4022 );
const vec3 yuv_g = vec3( 1.0000, -0.3457, -0.7145);
const vec3 yuv_b = vec3(1.0000, 1.7710, 0.0000);

vec4 pixel = sample(image, samplerCoord(image));
vec3 pel = pixel;
vec3 distort_u = sample(distort_u_map, samplerCoord(distort_u_map));
vec3 distort_v = sample(distort_v_map, samplerCoord(distort_v_map));

float delta_u = clamp((distort_u.x+distort_u.y+distort_u.z)/3.0,0.0,1.0)-0.5;
float delta_v = clamp((distort_v.x+distort_v.y+distort_v.z)/3.0,0.0,1.0)-0.5;
vec3 pixel_yuv;
pixel_yuv.x = dot(pel,rgb_y);
pixel_yuv.y = dot(pel,rgb_u);
pixel_yuv.z = dot(pel,rgb_v);

pixel_yuv.y = clamp(pixel_yuv.y + delta_u,0.0,1.0);
pixel_yuv.z = clamp(pixel_yuv.z + delta_v,0.0,1.0);

pel.r = dot(pixel_yuv,yuv_r);
pel.g = dot(pixel_yuv,yuv_g);
pel.b = dot(pixel_yuv,yuv_b);

vec3 result = (input_amount*pel) + inverse_amount*vec3(pixel);

return vec4(result.r, result.g, result.b,pixel.a);
}

Labels: chroma

SAMPLE: QameraSinCityRed.qtzThis kernel simulates a Sin City 1-color only type camera effect. It takes a "find_color" and a "replace_color". It samples each pixel in the source image and calculates the distance (in the RGB cube) from find_color. If the source pixel is within the threshold distance from the find_color, the kernel replaces the pixel in the output image with the replace_color; otherwise, it desaturates the pixel. In the sample, we've mapped the find_color and replace_color to the same color. But if you watch Robert Rodriquez's 15min film school, you will see they used YELLOW as the find_color and RED as the replace color in many situations. Also the sample QTZ has the sensitivity on a LFO to handle different lighting conditions.

kernel vec4 msBlackSinCityColorReplacement(sampler image, float input_threshold_normal, float threshold_sensitivity, __color find_color, __color replace_color)
{
float input_threshold_sensitivity = 2.*(1.0-clamp(threshold_sensitivity,0.0,1.0));
float input_threshold = clamp(pow(input_threshold_normal, input_threshold_sensitivity),0.0,1.0);
vec3 pel_rgb = unpremultiply(sample(image, samplerCoord(image)));
vec3 find_pel = vec3(find_color.r,find_color.g,find_color.b);
vec4 replace_pel = vec3(replace_color.r, replace_color.g, replace_color.b);
replace_pel.a = 1.0;
float distance_in_rgb_cube = distance(find_pel,pel_rgb);
float distance_abs = sqrt(distance_in_rgb_cube*distance_in_rgb_cube);
vec4 pel_avg = (pel_rgb.r + pel_rgb.g + pel_rgb.b)/3.0;
vec4 result = (distance_abs <input_threshold) ? replace_pel : pel_avg;
return result;
}

Labels: chroma