function getObject(name) {
		return document.getElementById(name);
}

function checkColors() {
		var brightnessThreshold = 125;
		var colorThreshold = 500;
		var bestBrightnessThreshold = brightnessThreshold * 1.1;
		var bestColorThreshold = colorThreshold * 1.1;
		var br, bg, bb, fr, fg, fb;
		var bY, fY;
		var brightnessDifference, colorDifference;
		var resultStr;

		br = parseInt(getObject('f1').value, 16);
		fr = parseInt(getObject('f2').value, 16);

		if(isNaN(br) || isNaN(fr)) {
				alert('Nesprávně zadané údaje!');
				return false;
		}

		bb = (0x0000ff & br);
		bg = (0x00ff00 & br) >> 8;
		br = (0xff0000 & br) >> 16;

		fb = (0x0000ff & fr);
		fg = (0x00ff00 & fr) >> 8;
		fr = (0xff0000 & fr) >> 16;

		bY=((br * 299) + (bg * 587) + (bb * 114)) / 1000;
		fY=((fr * 299) + (fg * 587) + (fb * 114)) / 1000;
		brightnessDifference = Math.abs(bY-fY);

		colorDifference = Math.max ((fr - br) , (br - fr)) + Math.max ((fg - bg) , (bg - fg)) + Math.max ((fb - bb) , (bb - fb));

		if ((brightnessDifference < brightnessThreshold) || (colorDifference < colorThreshold)) {
				resultStr = "NE";
		} else if ((brightnessDifference < bestBrightnessThreshold) && (colorDifference < bestColorThreshold)) {
				resultStr = "ČÁSTEČNĚ";
		} else {
				resultStr = "ANO";
		}

		getObject('brightness').value = brightnessDifference;
		getObject('color').value = colorDifference;
		getObject('compliant').value = resultStr;
		getObject('test').style.backgroundColor = 'rgb(' + br + ', ' + bg + ', ' + bb + ')';
		getObject('test').style.color = 'rgb(' + fr + ', ' + fg + ', ' + fb + ')';

		return false;
}