Note: Since all GIF support was removed from the GD library in version 1.6, this function is not available if you are using that version of the GD library. Support is expected to return in a version subsequent to the rerelease of GIF support in the GD library in mid 2004. For more information, see the GD Project site.

The following code snippet allows you to write more portable PHP applications by auto-detecting the type of GD support which is available. Replace the sequence header ("Content-type: image/gif"); imagegif ($im); by the more flexible sequence:

<?php if (function_exists("imagegif")) {     header("Content-type: image/gif");     imagegif($im); } elseif (function_exists("imagejpeg")) {     header("Content-type: image/jpeg");     imagejpeg($im, "", 0.5); } elseif (function_exists("imagepng")) {     header("Content-type: image/png");     imagepng($im); } elseif (function_exists("imagewbmp")) {     header("Content-type: image/vnd.wap.wbmp");     imagewbmp($im); } else {     die("No image support in this PHP server"); } ?>

Note: As of version 3.0.18 and 4.0.2 you can use the function imagetypes() in place of function_exists() for checking the presence of the various supported image formats:

<?php if (imagetypes() & IMG_GIF) {     header ("Content-type: image/gif");     imagegif ($im); } elseif (imagetypes() & IMG_JPG) {     /* ... etc. */ } ?>