Press Ctrl + + (Windows) or Command + + (Mac)
Press Ctrl + – (Windows) or Command + – (Mac)
Hold Alt and scroll the mouse wheel up or down (Windows)
Hold Option and scroll the mouse wheel up or down (Mac)
Select the Zoom Tool by pressing Z
Click the image to zoom in
Alt-click (Windows) or Option-click (Mac) to zoom out
Hold Spacebar and drag to pan while zoomed
Press Ctrl + 0 (Windows) or Command + 0 (Mac) to fit the image on screen
Press Ctrl + 1 (Windows) or Command + 1 (Mac) for 100% view