Experiment with Different Looks By Using Virtual Copies?

To make a virtual copy (an image that looks like the original and acts like the original, but doesn’t take up any space, so you can make as many virtual copies as you like and experiment to your heart’s content), click on an image then press Command-’ (apostrophe; PC: Ctrl-’). Your virtual copy appears right next to your original in the Develop module’s Filmstrip and in the Library module’s Grid view (that curled-page icon in the bottom-left corner of its thumbnail lets you know it’s a virtual copy). Now, you can mess with this copy all you want (I use this for trying out different white balances on the same image: I make five virtual copies, try a different white balance for each one, and then display them all onscreen at the same time by selecting them all, then pressing the letter N to enter Survey mode).