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Photoshop-like Contrast, Brightness and Levels for Filtrr2.js
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var rgba2hsla = function(rgba) { | |
var r = rgba.r/255, | |
g = rgba.g/255, | |
b = rgba.b/255, | |
max = Math.max(r,g,b), | |
min = Math.min(r,g,b), | |
h, s, l = (max + min)/2; | |
if(max==min){ | |
h = s = 0; | |
} else { | |
var d = max - min; | |
s = l > 0.5 ? d / (2 - max - min) : d / (max + min); | |
switch(max){ | |
case r: h = (g - b) / d + (g < b ? 6 : 0); break; | |
case g: h = (b - r) / d + 2; break; | |
case b: h = (r - g) / d + 4; break; | |
} | |
h /= 6; | |
} | |
return {h:h,s:s,l:l,a:rgba.a}; | |
}; | |
var hsla2rgba = function(hsla) { | |
var h = hsla.h, | |
s = hsla.s, | |
l = hsla.l, | |
r, g, b; | |
if(s == 0){ | |
r = g = b = l; | |
}else{ | |
function hue2rgb(p, q, t){ | |
if(t < 0) t += 1; | |
if(t > 1) t -= 1; | |
if(t < 1/6) return p + (q - p) * 6 * t; | |
if(t < 1/2) return q; | |
if(t < 2/3) return p + (q - p) * (2/3 - t) * 6; | |
return p; | |
} | |
var q = l < 0.5 ? l * (1 + s) : l + s - l * s; | |
var p = 2 * l - q; | |
r = hue2rgb(p, q, h + 1/3); | |
g = hue2rgb(p, q, h); | |
b = hue2rgb(p, q, h - 1/3); | |
} | |
return {r:r * 255, g:g * 255, b: b * 255, a: hsla.a}; | |
}; | |
// #### hue | |
Filtrr2.fx("hsl", function(h, s, l) { | |
h = Filtrr2.Util.clamp(h, -100, 100); | |
s = Filtrr2.Util.clamp(s, -100, 100); | |
l = Filtrr2.Util.clamp(l, -100, 100); | |
this.process(function(rgba) { | |
hsla = rgba2hsla(rgba); | |
hsla.h += h/100 * hsla.h; | |
hsla.s += s/100 * hsla.s; | |
hsla.l += l/100 * hsla.l; | |
newRgba = hsla2rgba(hsla); | |
rgba.r = newRgba.r; | |
rgba.b = newRgba.b; | |
rgba.g = newRgba.g; | |
}); | |
}); | |
// #### Contrast [-50, 100] | |
Filtrr2.fx("contrast", function(p) { | |
var p = Filtrr2.Util.normalize(p, -20, 40, -50, 100), | |
c1 = {x: 128 + p,y: 128 - p}, | |
c2 = {x: 128 - p,y: 128 + p}; | |
this.curves( | |
{x: 0, y: 0}, | |
c1, | |
c2, | |
{x: 255, y: 255} | |
); | |
}); | |
// #### Brightness [-150, 150] | |
Filtrr2.fx("brightness", function(p) { | |
var p = Filtrr2.Util.normalize(p, -70, 70, -150, 150), | |
c1 = {x: 185 - p, y: 185 + p}, | |
c2 = {x: 185 - p, y: 185 + p }; | |
this.curves( | |
{x: 0, y: 0}, | |
c1, | |
c2, | |
{x: 255, y: 255} | |
); | |
}); | |
// #### Levels | |
// channel [{rgb,r,g,b}] | |
// input black [0,255] | |
// input white [0,255] | |
// gamma [0.01, 9.99] | |
// output black [0,255] | |
// output white [0,255] | |
Filtrr2.fx("levels", function(channel, ib, iw, gm, ob, ow) { | |
var r = 0, | |
g = 0, | |
b = 0; | |
switch(channel){ | |
case "rgb" : r=1; g=1; b=1; break; | |
case "r" : r=1; break; | |
case "g" : g=1; break; | |
case "b" : b=1; break; | |
} | |
ib = Filtrr2.Util.clamp(ib, 0, 255); | |
iw = Filtrr2.Util.clamp(iw, 0, 255); | |
gm = typeof gm !== 'undefined' ? Filtrr2.Util.clamp(gm, 0.01, 9.99) : 1; | |
ob = typeof ob !== 'undefined' ? Filtrr2.Util.clamp(ob, 0, 255) : 0; | |
ow = typeof ow !== 'undefined' ? Filtrr2.Util.clamp(ow, 0, 255) : 255; | |
this.process(function(rgba) { | |
if(r){rgba.r = Filtrr2.Util.normalize(255 * Math.pow(Filtrr2.Util.normalize(rgba.r, 0, 255, ib, iw)/255, 1/gm), ob, ow, 0, 255);} | |
if(g){rgba.g = Filtrr2.Util.normalize(255 * Math.pow(Filtrr2.Util.normalize(rgba.g, 0, 255, ib, iw)/255, 1/gm), ob, ow, 0, 255);} | |
if(b){rgba.b = Filtrr2.Util.normalize(255 * Math.pow(Filtrr2.Util.normalize(rgba.b, 0, 255, ib, iw)/255, 1/gm), ob, ow, 0, 255);} | |
}); | |
}); |
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