pixlomatic's amber in php

<?php

$im=imagecreatefromjpeg("filename.JPG");

$w=imagesx($im);
$h=imagesy($im);

$red=array();
$green=array();
$blue=array();

$nred= [0,2,3,5,7,8,10,12,13,15,17,18,20,22,24,25,27,29,30,32,34,35,37,38,40,42,43,45,47,48,50,52,53,55,57,58,60,61,63,65,66,68,69,71,73,74,76,77,79,80,82,83,85,87,88,90,91,93,94,96,97,99,100,102,103,105,106,107,109,110,112,113,115,116,117,119,120,121,123,124,126,127,128,130,131,132,133,135,136,137,139,140,141,142,143,145,146,147,148,149,151,152,153,154,155,156,157,158,159,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,179,180,181,182,183,184,185,186,187,187,188,189,190,191,192,192,193,194,195,196,196,197,198,199,199,200,201,202,202,203,204,205,205,206,207,207,208,209,209,210,211,211,212,213,213,214,215,215,216,216,217,218,218,219,219,220,221,221,222,222,223,224,224,225,225,226,226,227,227,228,228,229,230,230,231,231,232,232,233,233,234,234,235,235,236,236,237,237,238,238,238,239,239,240,240,241,241,242,242,243,243,244,244,244,245,245,246,246,247,247,248,248,248,249,249,250,250,251,251,252,252,252,253,253,254,254,255,255];


$ngreen= [0,1,1,2,3,3,4,4,5,6,6,7,8,8,9,10,10,11,11,12,13,13,14,15,15,16,17,17,18,19,19,20,20,21,22,22,23,24,24,25,26,26,27,28,28,29,30,30,31,32,33,33,34,35,35,36,37,37,38,39,40,40,41,42,42,43,44,45,45,46,47,47,48,49,50,50,51,52,53,53,54,55,56,57,57,58,59,60,60,61,62,63,64,65,65,66,67,68,69,69,70,71,72,73,74,75,75,76,77,78,79,80,81,82,83,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,118,119,120,121,122,123,124,125,127,128,129,130,131,132,133,135,136,137,138,139,141,142,143,144,145,147,148,149,150,152,153,154,155,157,158,159,160,162,163,164,165,167,168,169,171,172,173,174,176,177,178,180,181,182,184,185,186,188,189,190,192,193,194,196,197,198,200,201,202,204,205,207,208,209,211,212,213,215,216,217,219,220,222,223,224,226,227,229,230,231,233,234,235,237,238,240,241,242,244,245,247,248,249,251,252,254,255];


$nblue= [127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128];



for($x=0; $x<$w; $x++){
    for($y=0; $y<$h; $y++){
        $idx=imageColorAt($im,$x,$y);
        list($r,$g,$b)=array_values(imageColorsForIndex($im,$idx));
        $nr=$nred[$r];
        $ng=$ngreen[$g];
        $nb=$nblue[$b];

        $col=imageColorAllocate($im,$nr,$ng,$nb);
        imageSetPixel($im,$x,$y,$col);
    }
}
imagepng($im,'./experiment.png');



?>