note 48900 added to function.imagecolortransparent

After much devious mindbending, I have found a way to test any GIF for presence of background transparency. This ability is essential for my application which uploads any of GIF, JPEG or PNG and simultaneously creates a thumbnail of identical image type and identical filename (full size and thumbnail versions being stored in different folders). After uploading and moving the image in the usual way, a switch($image_type) statement ensures that the optimum code is used to generate the thumbnail; regardless of image type. The problem with the GIF type is that those with transparent backgrounds need to be treated differently to those without. When I don't detect GIF transparency, I either end up with all transparent GIF's having black backgrounds, or all GIF's get converted to transparent background - even if they weren't transparent in the original. But how to detect transparency in the original? It finally occurred to me that I could test for transparency programmatically by overlaying a copy of the original image over an all-black image, record the color value at particular pixel locations and then repeat the process by overlaying a copy of the original image over an all-white image, recording the color values at identical pixel locations and comparing these with the first set of values. If the two sets of values correlate exactly, and if sensible sampling points are used, the image can be treated as non-transparent. If the two sets of values show differences, the image should be treated as having a transparent background. ---- Manual Page -- http://www.php.net/manual/en/function.imagecolortransparent.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+48900 Delete -- http://master.php.net/manage/user-notes.php?action=delete+48900&report=yes Reason: bad code -- http://master.php.net/manage/user-notes.php?action=delete+48900&report=yes&reason=bad+code Reason: spam -- http://master.php.net/manage/user-notes.php?action=delete+48900&report=yes&reason=spam Reason: useless example -- http://master.php.net/manage/user-notes.php?action=delete+48900&report=yes&reason=useless+example Reason: contains commercial links -- http://master.php.net/manage/user-notes.php?action=delete+48900&report=yes&reason=contains+commercial+links Reason: useless note -- http://master.php.net/manage/user-notes.php?action=delete+48900&report=yes&reason=useless+note Reject -- http://master.php.net/manage/user-notes.php?action=reject+48900&report=yes Search -- http://master.php.net/manage/user-notes.php