The Galaxy S uses the default wallpaper resolution of 980 x 800 pixels. This is for the sliding home screen with multiple screens.
In order to make a decent high resolution image and not all blurry do the following:
- Using a paint program like paint in windows or Paint Shop Pro etc. Make a new image with 980 x 800 as the dimensions.
- Re-size the image you want to use to fit into this more or less.
- Then paste the photo or image you want into the new image. And move to fit.
- Save the image as a PNG for maximum quality (The image will be around 1mb in size)
Here's an example I made (This photo was actually taken on the Galaxy S)
Now last step, transfer wallpaper over to your SGS. And on your Galaxy S, select the gallery as the wallpaper.
Find your image and then make sure you crop the whole image and not just the middle of it for maximum sharpness.
(See below image)
Save and enjoy your high resolution wallpaper.