psp is used by photoshop.
mp4 or PSP Video format
Is this an image from a digital camera? If its a JPG, its probably larger than 2048x1536 isn't it. Any image larger than that will throw an "Unsupported Format Error". If its a BMP it has to be less than 150KB in size for the PSP, but based on your question I bet its a JPG.
Mpeg-4
One possible answer could be that you didn't save the pictures into a file format that the psp can read, try looking at the file format and then look at the psp compatible files.
any format.....but the resolutin is 480 x 272
Your video has to be MP4 format. You have to connect PSP and computer then you drag and drop the video file in the PSP VIDEO folder.
You can go onto the internet with the PSP and then click file and save image
The image file you used as the wallpaper for your psp may not be recognised by the software on the psp, the exact software in question is called a codec (most think these are just for videos but are used for music and image files), computers have a larger range of image software and therefore more likely to have the codec needed to read the file.
There is a free program for Windows, worths a try: http://www.processtext.com/abcpaintshop I renamed xxxxxx.pspimage to xxxxx.psp and this tool converted it to the format I choosed from the many on the list. However the app opens only .pspimage, and there is no way to change this, so you have to rename the file. Hopes it helps.
'MP4' is a 'container' format, combining both audio and video information into one file. These separate 'streams' are themselves encoded, and there are many forms of compression they can use. The PSP can't always decode these streams - in short, not all files with the extension 'mp4' are made the same way. A file may play perfectly on a PC, but not the PSP because of this. What you need to do is use a program such as Super or PSP Video 9. You can run the mp4 file through it, and it can create another version of it specifically to work on the PSP.
you go to the pic you want then you hit triangle the you go to the file then you click save this image To transfer files you hit send. The other psp should hit receive. (both on menu) NOTE: if your psp has the I.R. port mod then you can use that.