How to resize an image in ubuntu

Warning (insert Bourbaki dangerous bend sign here): This process overrides the original file. So if the original image is at all important, it must first be copied.
 

Step 1: Right-click and select Open With GIMP Image Editor

Step 2: File -> Save.

Step 3: Click “Show preview in image window”

Step 4: Slide the quality to get the desired file size. 

and we’re done.