public static function convertRGBToXY($red, $green, $blue)
{
// Normalize the values to 1
$normalizedToOne['red'] = $red / 255;
$normalizedToOne['green'] = $green / 255;
$normalizedToOne['blue'] = $blue / 255;
// Make colors more vivid
foreach ($normalizedToOne as $key => $normalized) {
if ($normalized > 0.04045) {
$color[$key] = pow(($normalized + 0.055) / (1.0 + 0.055), 2.4);
} else {
$color[$key] = $normalized / 12.92;
}
}
// Convert to XYZ using the Wide RGB D65 formula
$xyz['x'] = $color['red'] * 0.664511 + $color['green'] * 0.154324 + $color['blue'] * 0.162028;
$xyz['y'] = $color['red'] * 0.283881 + $color['green'] * 0.6684330000000001 + $color['blue'] * 0.047685;
$xyz['z'] = $color['red'] * 0.0 + $color['green'] * 0.07231 + $color['blue'] * 0.986039;
// Calculate the x/y values
if (array_sum($xyz) == 0) {
$x = 0;
$y = 0;
} else {
$x = $xyz['x'] / array_sum($xyz);
$y = $xyz['y'] / array_sum($xyz);
}
return array('x' => $x, 'y' => $y, 'bri' => round($xyz['y'] * 255));
} /**
* Test: convert RGB to XY and brightness
*
* @covers \Phue\Helper\ColorConversion::convertRGBToXY
*/
public function testConvertRGBToXY()
{
// Values from: http://www.developers.meethue.com/documentation/hue-xy-values
// Alice Blue
$xy = ColorConversion::convertRGBToXY(239, 247, 255);
$this->assertEquals(0.3088, $xy['x'], '', 0.0001);
$this->assertEquals(0.3212, $xy['y'], '', 0.0001);
$this->assertEquals(233, $xy['bri']);
// Firebrick
$xy = ColorConversion::convertRGBToXY(178, 33, 33);
$this->assertEquals(0.6622, $xy['x'], '', 0.0001);
$this->assertEquals(0.3024, $xy['y'], '', 0.0001);
$this->assertEquals(35, $xy['bri']);
// Medium Sea Green
$xy = ColorConversion::convertRGBToXY(61, 178, 112);
$this->assertEquals(0.1979, $xy['x'], '', 0.0001);
$this->assertEquals(0.5004999999999999, $xy['y'], '', 0.0001);
$this->assertEquals(81, $xy['bri']);
}
