Example

$color = new \ImagickPixel('rgba(90%, 20%, 20%, 0.75)');
$output =  "Alpha value is " . $color->getColorValue(\Imagick::COLOR_ALPHA) . "<br/>";
$output .=  "" . "<br/>";
$output .=  "Red value is " . $color->getColorValue(\Imagick::COLOR_RED) . "<br/>";
$output .=  "Green value is " . $color->getColorValue(\Imagick::COLOR_GREEN) . "<br/>";
$output .=  "Blue value is " . $color->getColorValue(\Imagick::COLOR_BLUE) . "<br/>";
$output .=  "" . "<br/>";
$output .=  "Cyan value is " . $color->getColorValue(\Imagick::COLOR_CYAN) . "<br/>";
$output .=  "Magenta value is " . $color->getColorValue(\Imagick::COLOR_MAGENTA) . "<br/>";
$output .=  "Yellow value is " . $color->getColorValue(\Imagick::COLOR_YELLOW) . "<br/>";
$output .=  "Black value is " . $color->getColorValue(\Imagick::COLOR_BLACK) . "<br/>";