When working with Layers in Photoshop, one of the most powerful tools for lossless editing is the use of adjustment layers. Rather than actually changing the pixels in the content layer (i.e. altering the original image), you can use an adjustment layer to virtually put a filter over the layer and make the layer hold the adjustment for you. Turn off the adjustment layer and you’ll see your original image remains untouched below.
Adjustment layers, by default, modify every layer below them. Unless you know this one trick. No, it won’t give you great abs or help you lose ten pounds in ten days, but it will absolutely make you think Adjustment Layers are even better and more useful than you ever knew they could be. Along the bottom edge of the Adjustment Layer panel, there’s a series of icons that do various things. The icon on the far left, which looks like a box with an arrow emerging from it, making a 90-degree turn and pointing at the layer below, does something called “Clip To Layer Below.”
This button does exactly what its icon and name both imply: it applies the adjustment layer’s modifications exclusively to the layer directly below, and doesn’t affect any other layers at all. This simple checkbox can make adjustment layers infinitely more powerful and customizable, because instead of making wholesale changes to the entire image, subtle adjustments to individual layered elements are much easier to make without losing the lossless versatility of adjustment layers. If you’ve never bothered to investigate all those little icons you might not have any idea this great tool exists. But now that you know, and you’re sure to love your layered workflow even more.