function p($a)
    {
        return ($a / p2m) * m2p;
    }

    // spul van DB
    $dpi = 200;
    $canvasSize = explode('x', '40x40');
    $editor['size'] = [347, 347]; // size inside gray blocks, in this example a 40x40cm;

    // vars nodig voor convert
    $m2p = (0.03937007874 * $dpi);  // mm to pixel conversion variable;
    $c2p = $m2p * 10;               // cm to pixel conversion variable;
    $p2m = $editor['size'][0] / ($canvasSize[0] * 10); // 347/400, also, canvas size converted to mm

    // get the size in pixels for the canvas.
    $canvas['size'] = [$canvasSize[0] * $c2p, $canvasSize[1] * $c2p];

    $img['sze'] = [p($imd['sze'][0]), p($imd['sze'][1])];