I'm attempting to create a script that accepts  bmp and jpg files uploaded by a user and converts them into jpg or bmp files as requested by the user, using the ImageCreateFromWBMP, and ImageJPEG functions. But, each time I upload a BMP or JPEG image, I get the message:

"Warning: imagecreatefromwbmp: 'image.bmp' is not a valid WBMP file in /script/location/here.php on line#"

These BMP and jpeg images are created in photoshop 5.5, and windows paint program on win 2000, and 98 platforms and according to thos programs, the file-types are valid.

But, if I use the imagecreate function to generate a  jpeg image (from a string of text), save, and upload that jpeg file to my server, then run the same script on it to convert it to another file format, no error/warning messages are generated.... So apparantly, php can work on images generated by a php script, but no others.

What makes it even more odd, is that upon uploading an image (one made in photoshop or paint) using my script, I have it setup such that a confirmation screen is generated where the users are provided with the size and format/type of the uploaded file, and theyre always reported as being:
image/jpg
or image/bmp
yet they are flagged as invalid when another php script attempts to manipulate them.

is the problem on my end, am I doing something wrong? Is it that php can't handle images created by photoshop  and paint?  or is that the criteria used to validate the image format in php is flawed?

Thanx.