-compare

Function
This command loads a second image into a Viewer buffer so you can compare two images. When the image is loaded in, you drag the left button with Alt to reveal the second image.

Command Line

shake image1 -compare [zoom] image2

Example

This loads an image, flops it over and then compares it to the original image:

shake lisa.iff -flop -compare lisa.iff
Keyboard Keys Function
Alt+drag Scrubs between the two images
H Sets a horizontal reveal of the images
V Sets a vertical reveal of the images
F Fades between the two image, SGI only
S Switches the buffer locations.