Press L to load one or more images.
Press DEL to remove the current image.
Use left and right arrows to cycle through images.
Press F11 to enter full screen mode.
Press R to rotate the image 90 degrees counter clockwise.
Press X to reset the transformation.
Press W to toggle a blank white screen.
Press B to toggle a blank black screen.
Press D to toggle a demo mode.
Press S to load a sample image.

Click here for an overview of MasterCopy.