PHP - Find the closest RGB to predefined RGB from list

Question

My goal is to find the closest match of RGB compared to the RGB from the array. I have already created a function that loops trough every pixel in a picture. The only thing I need now is to find closest color of each pixel in the picture to the color from the array.

$colors = array(
    array(221,221,221),
    array(219,125,62),
    array(179,80,188),
    array(107,138,201),
    array(177,166,39),
    array(65,174,56),
    array(208,132,153),
    array(64,64,64),
    array(154,161,161),
    array(46,110,137),
    array(126,61,181),
    array(46,56,141),
    array(79,50,31),
    array(53,70,27),
    array(150,52,48),
    array(25,22,22)
);

I tried converting picture to 8bits to reduce number of colors and compare them later in database but that just doesn't seem to be a good idea.

Answer 1

Try it like this:

$inputColor = array(20,40,80);

function compareColors($colorA, $colorB) {
    return abs($colorA[0] - $colorB[0]) + abs($colorA[1] - $colorB[1]) + abs($colorA[2] - $colorB[2]);
}

$selectedColor = $colors[0];
$deviation = PHP_INT_MAX;

foreach ($colors as $color) {
    $curDev = compareColors($inputColor, $color);
    if ($curDev < $deviation) {
        $deviation = $curDev;
        $selectedColor = $color;
    }
}

var_dump($selectedColor);

The advantage of this solution is that you can easily replace the comparison function. It might also be possible to use

Disclaimer: There might be more elegant ways of implementation, perhaps leveraging map.