Color filtering known from Photoshop in JavaScript

colorize.js

var colorize = {
    blendColorValue : function (color1,color2,method){
        if(typeof color1 == 'undefined'){
            color1 = 0;
        }

        if(typeof color2 == 'undefined'){
            color2 = 0;
        }

        if(typeof this[method] == 'undefined'){
            return color1;
        }

        var r1 = color1 >> 16,
            g1 = color1 >> 8 & 0x00FF,
            b1 = color1 & 0x0000FF,

            r2 = color2 >> 16,
            g2 = color2 >> 8 & 0x00FF,
            b2 = color2 & 0x0000FF;

        return parseInt((this[method](r1,r2) << 16) + (this[method](g1,g2) << 8) + (this[method](b1,b2)));
    },
    multiply: function(channel1,channel2){
        return (channel1*channel2)/0xFF;
    },
    screen : function(channel1,channel2){
        return (channel1+channel2-(channel1 * channel2))/0xFF;
    },
    overlay : function (channel1,channel2){
        return (channel2 < 0x80) ? (2 * channel1 * channel2 / 0xFF):(0xFF - 2 * (0xFF - channel1) * (0xFF - channel2) / 0xFF);
    },
    softlight : function(channel1,channel2){
        if (channel1 > 0x7F){
            return channel2 + ((0xFF - channel2) * ((channel1 - 0x7F) / 0x7F) * (Math.abs(channel2-0x7F)/0xFF));
        }else{
            return channel2 - (channel2 * ((0x7F -  channel1) / 0x7F) * (Math.abs(channel2-0x7F)/0xFF));
        }
    },
    hardlight : function(channel1,channel2){
        if (channel1 > 0x7F){
            return channel2 + ((0xFF - channel2) * ((channel1 - 0x7F) / 0x7F));
        }else{
            return channel2 * channel1 / 0x7F;
        }
    },
    colorDodge : function(channel1,channel2){
        return (channel1 === 0xFF)?channel1:Math.min(0xFF,((channel2 << 8 ) / (0xFF - channel1)));
    },
    colorBurn : function(channel1,channel2){
        return (channel1 === 0)?channel1:Math.max(0,(0xFF - ((0xFF - channel2) << 8 ) / channel1));
    },
    linearcolordodge : function(channel1,channel2){
        return min(channel1 + channel2, 0xFF);
    },
    linearcolorburn : function(channel1,channel2){
        return ((channel1 + channel2) < 0xFF)?0:(channel1 + channel2 - 0xFF);
    },
    darken : function(channel1,channel2){
        return Math.min(channel1,channel2);
    },
    lighten : function(channel1,channel2){
        return Math.max(channel1,channel2);
    },
    difference : function(channel1,channel2){
        return Math.abs(channel1-channel2);
    },
    exclusion : function(channel1,channel2){
        return channel1 + channel2 - (channel1 * channel2 / 0x7F);
    },
    reflex : function(channel1,channel2){
        return ((channel1 === 0xFF) ? channel1:Math.min(0xFF, (channel2 * channel2 / (0xFF - channel1))));
    },
    linearlight : function(channel1,channel2){
        return (channel1 < 0x7F) ? this.linearcolorburn(channel2,(2 * channel1)) : this.linearcolordodge(channel2,(2 * (channel1 - 0x7F)));
    },
    pinlight : function(channel1,channel2){
        return (channel1 < 0x7F) ? this.darken(channel2,(2 * channel1)) : this.lighten(channel2,(2 * (channel1 - 0x7F)));
    },
    vividlight : function(channel1,channel2){
        return (channel1 < 0x7F) ? this.colorBurn(channel2,(2 * channel1)) : this.colorDodge(channel2,(2 * (channel1 - 0x7F)));
    },
    hardmix : function(channel1,channel2){
        return this.vividlight(channel1,channel2) > 0x7F ? 0 : 255;
    }
};