PHP: Converting png's and gif's into grayscale

Question

im using the following script to convert jpgs into grayscale-images. http://bubble.ro/How_to_convert_an_image_to_grayscale_using_PHP.html

i want to upgrade it to also co

Answer 1

thank you!

imagefilter($img, IMG_FILTER_GRAYSCALE);

it's almost working. i'm still having problems with transprency. pngs with transparent background get transformed to black (the background is black). The same happens to gifs and moreover gifs with transprency don't get properly grayscaled. There are a few very graytoned colors, however there are pale greentones and redtones in it.