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« on: October 09, 2018, 07:46:44 AM »
I jsut developed a small shader for colorizing, it uses HSL color space which looks much better than HSV. But in the code you can find some useful color conversion functions that you can use for many purposes like desaturation, hue rotation etc.
The shader requires an HSL vector of three values that are used for colorizing, plus a texture mix value if you want to blend (in RGB) the colorized with the default image.
uniform sampler2D texture;
uniform vec3 hsl;
uniform float texmix;
vec3 hsl2rgb( in vec3 c )
{
vec3 rgb = clamp( abs(mod(c.x*6.0+vec3(0.0,4.0,2.0),6.0)-3.0)-1.0, 0.0, 1.0 );
return c.z + c.y * (rgb-0.5)*(1.0-abs(2.0*c.z-1.0));
}
vec3 rgb2hsl( in vec3 c ){
float h = 0.0;
float s = 0.0;
float l = 0.0;
float r = c.r;
float g = c.g;
float b = c.b;
float cMin = min( r, min( g, b ) );
float cMax = max( r, max( g, b ) );
l = ( cMax + cMin ) / 2.0;
if ( cMax > cMin ) {
float cDelta = cMax - cMin;
//s = l < .05 ? cDelta / ( cMax + cMin ) : cDelta / ( 2.0 - ( cMax + cMin ) ); Original
s = l < .0 ? cDelta / ( cMax + cMin ) : cDelta / ( 2.0 - ( cMax + cMin ) );
if ( r == cMax ) {
h = ( g - b ) / cDelta;
} else if ( g == cMax ) {
h = 2.0 + ( b - r ) / cDelta;
} else {
h = 4.0 + ( r - g ) / cDelta;
}
if ( h < 0.0) {
h += 6.0;
}
h = h / 6.0;
}
return vec3( h, s, l );
}
vec3 rgb2hsv(vec3 c)
{
vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
float d = q.x - min(q.w, q.y);
float e = 1.0e-10;
return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
}
vec3 hsv2rgb(vec3 c)
{
vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
}
void main()
{
vec2 uv = gl_TexCoord[0].xy;
vec4 t0 = texture2D(texture, uv);
vec3 hsl0 = rgb2hsl (t0.rgb);
vec3 hsl1 = vec3(hsl.x,hsl.y,hsl0.z);
vec3 tch = hsl2rgb (hsl1);
gl_FragColor = vec4(mix(hsl.z*tch.xyz,t0.xyz,texmix) , gl_Color.a*t0.a);
}
This is a sample layout
local pic1 = fe.add_artwork("snap",0,0,400,400)
pic1.video_flags = Vid.ImagesOnly
pic1.preserve_aspect_ratio = false
local pic2 = fe.add_artwork("snap",400,0,400,400)
pic2.video_flags = Vid.ImagesOnly
pic2.preserve_aspect_ratio = false
local pic3 = fe.add_artwork("snap",800,0,400,400)
pic3.video_flags = Vid.ImagesOnly
pic3.preserve_aspect_ratio = false
local colorshader1 = fe.add_shader(Shader.Fragment,"colorizer.glsl")
colorshader1.set_texture_param("texture")
colorshader1.set_param("hsl",0.6,0.5,1.0)
colorshader1.set_param("texmix",0.0)
pic1.shader = colorshader1
local colorshader2 = fe.add_shader(Shader.Fragment,"colorizer.glsl")
colorshader2.set_texture_param("texture")
colorshader2.set_param("hsl",0.6,1.0,1.0)
colorshader2.set_param("texmix",0.0)
pic2.shader = colorshader2
Show Posts
) work best with a reduced texture size, for example a gaussian blur on a 128x128 pixel image can be smoother with few semples, while the same gaussian blur on a 512 x 512 pixel image requires a lot of samples. In AM I use this trick of adding the 512x512 image on a 128x128 surface, then apply the shader on the surface and rescale it to the desired size. 