generate random color with same colore tone

randcolorhue.js

function randcolorhue(rgb) {	//generate random color with same colore tone
	var hsl = rgb2hsl(rgb);
	var newhsl = [ Math.min(hsl[0]*minmaxrandom(0.95,1.05),1), hsl[1]*minmaxrandom(0.7,1), Math.min(hsl[2]*minmaxrandom(0.8,1.2),1) ];
	//stessa tonalita'
	return hsl2rgb(newhsl);
}

function minmaxrandom(min, max)	//genera numero casuale compreso in un range di valori
{
	return Math.random() * (max - min) + min;
}

function rgb2hsl(rgb) {
	var r,g,b;
	r=rgb[0];g=rgb[1];b=rgb[2];
	
    r /= 255, g /= 255, b /= 255;
    var max = Math.max(r, g, b), min = Math.min(r, g, b);
    var h, s, l = (max + min) / 2;

    if(max == min){
        h = s = 0; // achromatic
    }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, s, l];
}

/**
 * Converts an HSL color value to RGB. Conversion formula
 * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
 * Assumes h, s, and l are contained in the set [0, 1] and
 * returns r, g, and b in the set [0, 255].
 */
function hsl2rgb(hsl) {
	var h,s,l;
	h=hsl[0];s=hsl[1];l=hsl[2];

    var r, g, b;

    if(s == 0){
        r = g = b = l; // achromatic
    }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 [Math.ceil(r * 255), Math.ceil(g * 255), Math.ceil(b * 255)];
}