The convert program is a member of the ImageMagick suite of tools. Use it to convert between image formats as well as resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more.
Getting the convert tool
The ImageMagick suite should be inside your extra packages. It might not be installed by default depending on your distribution. If it is not the case, simply install it with the following command.
On a Debian base distributions, do the following.
apt-get install imagemagick
On ArchLinux based distributions, do the following.
pacman -S imagemagick
How to use
Convert an image file to an other format
The following formats are supported: .jpg, .bmp, .pcx, .gif, .png, .tiff, .xpm, and .xwd
convert car.jpg car.png convert cake.gif cake.bmp convert icon.tiff icon.pcx
Resize an image
To resize to a specific pixel width and height, use the -resize flag.
convert -resize 800x600 wolf.jpg wolf-small.jpg
To resize to a specific percentage, use the -sample flag.
convert -sample 50%x50% beach.png beach-small.png
Rotate an image
You can rotate an images from 0 to 360 degrees. You can also use negative degree values. To rotate, use the -rotate flag.
These two will create the same image since 270 and -90 degree are the same.
convert -rotate 270 RWBY.png RWBY_270.png convert -rotate -90 RWBY.png RWBY_-90.png
This example rotates the image by 29 degrees (to the right).
convert -rotate 29 boat.jpg boat_29.jpg
Flip and image horizontally and vertically
Use -flip to flip an image horizontally.
convert -flip house.jpg house-vertical.jpg
Use -flop to flip an image vertically.
convert -flop spaceship.bmp spaceship-horizontal.bmp
Combine the flags
Bonus: you can append those flags inside the same command. You could change the file type as you are using the -resize and -flip flags.
Sources
- Negus, Christopher, and François Caen.Ubuntu Linux toolbox: 1000+ commands for Ubuntu and Debian power user. John Wiley & Sons, 2008.