Turn the color black if its r + b> 150

Question

I looked at SO, but I could not find a single similar question.

After opening the image in PHP, I want to check every pixel, and if their red + green values ​​are below 150, I would turn that pixel to white, instead, if the sum is above 150, I would turn it from a pixel to black.

Is it possible?

I tried with imagefilter() , but I can't get it to work properly. Perhaps there are more suitable features.

Answer 1

sort of

 $image = imagecreatefrompng($img); $xdim = imagesx($image); $ydim = imagesy($image); for ($x = 1; $x <= $xdim-1; $x++) { for ($y = 1; $y <= $ydim-1; $y++) { $rgb = imagecolorat($image, $x, $y); if($rgb>150) $color = 0x00; else $color = 0xFF; } } 

Answer 2

Look at using the imagecolorat function (I think it might be part of the GD library). You can get RGB from this. Then use imagecolorset to set the new RGB.