Q: How to convert Wallpaper to Splash Image for GRUB menu?

1. Read General Notes

2. e.g. Assumed that wallpaper.png is the Wallpaper to be converted to Splash Image
        splashimage.xpm.gz is the Splash Image for GRUB menu

3. convert -resize 640x480 -colors 14 wallpaper.png splashimage.xpm && gzip splashimage.xpm

4. Read How to display Splash Image for GRUB menu on boot-up? (use splashimage.xpm.gz instead of ubuntu.xpm.gz)