Loupe (` key) is a very powerful feature in Aperture and Lightroom is missing. You can use it in any scenario of your working space no matter in viewer pane, grid view pane or full screen. It can show you the actual size of pixels of the area you’re pointing to. But I just know you can have more fun with it!
Try to right-click or ctrl-click on the loupe, it will popup context menu with some loupe customization items. I want to show is Use Centered Loupe, I feel it’s more handy and easy to control than the default loupe style because that will rotate sometimes.
For Color Value, you can see the RGB value of the pixel in the center of the loupe. Also you can select 100%, 200%, 400%, 800% 1600% as the loupe magnification ratio.
