ImageMagick (convert) tool could be used for different image manipulation tasks. Here I will mention some of them I have used it for.

Get verbose information about image

# convert some_test_image.jpg -verbose info:

 

Change JPEG image quality

# convert original_image.jpg -quality 50 new_image_with_50_quality.jpg

 

Convert/Resize image to 1600×1600 to fit ebay requirements

I need this conversion in order my images to fit the Ebay image size limits, which are also 1600×1600 pixels. Here is the the deal:

convert IMAGE_ORIG.jpeg -resize 1600×1600  IMAGE_RESIZED.jpeg