一些颜色相关的算法

RBG转灰度

//rgba(grey,grey,grey,1)
function rgb2Grey(r,g,b)
{
	var grey=Math.round((r*299 + g*587 + b*114 + 500) / 1000)
	return grey
}

判断两种颜色相似程度

//rbg
function isSimilarColorRBG(r1, g1, b1, r2, g2, b2, offset)
{
	if (Math.sqrt((r1 - r2) * (r1 - r2) + (g1 - g2) * (g1 - g2) + (b1 - b2) * (b1 - b2)) < offset)
	{
		return true;
	}
	else
	{
		return false;
	}
}

//hex
function isSimilarColorHEX(sHexColorA, sHexColorB, nOffset)
{
	this.offsetNum = Math.abs(nOffset);
	this.offsetNum > 255 ? this.offsetNum = this.offsetNum - 256 : "";
	var arrNumA = [parseInt(sHexColorA.substring(0, 2), 16),
		parseInt(sHexColorA.substring(2, 4), 16),
		parseInt(sHexColorA.substring(4, 6), 16)
	];
	var arrNumB = [parseInt(sHexColorB.substring(0, 2), 16),
		parseInt(sHexColorB.substring(2, 4), 16),
		parseInt(sHexColorB.substring(4, 6), 16)
	];
	for (var i = 0; i < arrNumA.length; i++)
	{
		if (Math.abs(arrNumA[i] - arrNumB[i]) > this.offsetNum)
		{
			return false;//不相似
		};
	}
	return true;//相似
}

　　

RGB转HEX

//rgb2Hex("rbg(r,g,b)")

function rgb2Hex(rgb)
{
	var color = rgb.toString().match(/d+/g); 
	var hex = "#";
	for (var i = 0; i < 3; i++)
	{
		hex += ("0" + Number(color[i]).toString(16)).slice(-2);
	}
	return hex;
}

　

HEX转RGB

//hex2Rgb("#ff00ff")
function hex2Rgb(a)
{
    if (a.substr(0, 1) == "#") a = a.substring(1);
    var len = a.length;
    a = a.toLowerCase();
    var b = new Array();
    for (x = 0; x < 3; x++)
    {
        b[0] = len == 6 ? a.substr(x * 2, 2) : a.substr(x * 1, 1) + a.substr(x * 1, 1);
        b[3] = "0123456789abcdef";
        b[1] = b[0].substr(0, 1);
        b[2] = b[0].substr(1, 1);
        b[20 + x] = b[3].indexOf(b[1]) * 16 + b[3].indexOf(b[2])
    }
    console.log(b[20] + "," + b[21] + "," + b[22]);
}