Scale an image with no interpolation
convert source.[png|gif|...] -scale 400% target.[png|gif|...]
The scale option can also take integer parameters (without the percent sign) to indicate the target size.
Remove metadata from an image
Useful for preserving Online privacy when publishing images. Pictures taken with smartphones and other modern devices often contain large amounts of data about location, time and date and device type.
Exiftool
`exiftool -all= image.jpg`