Re: B/W Image

Ulrik Witschass wrote:

Hello List, I browses the PHP Manual for some time now but didn't find exactly what I was looking for. I need to turn images uploaded by a user to b/w images to use them in pdflib, the resulting PDF has to be black and white. Now my question: a) is this possible? yes, it is.

if(a) b) do I do this with PHP Image functions (maybe colorallicate and stuff like that) or is it possible to actually do that in PDFLib? I don't think it's doable using PDFLib, but you could write an implementation yourself. Here's one I just wipped up (so it might not work correctly).

<?php $im = imagecreatefromWHATEVER($path); $size = getimagesize($path); $width = $size[0]; $height = $size[1]; $greyScaled = imagecreate($width, $height); $pallet = array(); for($y=0;$y<$height;$y++) { for($x=0;$x<$width;$x++) { $index = imagecolorat($im, $x, $y); $rgba = imagecolorsforindex($im, $index); $newC = (($rgba['red']+$rgba['green']+$rgba['blue'])/3) if(!isset($pallet[$newC])) { $color = imagecolorallocate($greyScaled, $newC, $newC, $newC); } else { $color = $pallet[$newC]; } imagesetpixel($greyScaled, $x, $y, $color); } } header('Content-type: image/png'); imagepng($greyScaled); imagedestroy($im); imagedestroy($greyScaled); ?>

thanks in advance for any help Ulrik