You’ll be amazed at what you can do when using the Blend If sliders. You can blend based off of information from the Layer you are on, or based off of information from the rest of the image. You can also target highlights or shadows which will definitely come in handy when you are using the Dodge & Burn technique.
We create a layer with the Colors: Black, White, Red, Green and Blue. We then pull up our Blend If dialog. We pay attention to the two sliders. The top slider uses information from the Layer you’re currently on. The bottom slider uses information from the rest of the image. We start with our top slider and as we slide from left to right we are left with only the White Color remaining. If we use the top slider and slide from right to left, the Colors disappear in the opposite order. Something else that’s awesome about Blend If sliders is that you can choose your default Colors.
The bottom slider uses the information from the rest of the image to see what’s going to be visible and invisible. As we drag our slider from left to right, the information is pulled based off of what we have on the Underlying Layer. When we drag from right to left, the Lights in the image disappear first and then the darks.
The last helpful tip with Blend If is the feathering option. Hold Alt or Option which will separate our sliders and allow us to feather our blending. The same effect still applies when moving the slider from one side to another, the Difference is it isn’t as choppy as it was before. When using Blend If, we do advise that you use feathering. That’ll help give a more realistic approach.
We create a New Layer on top of our image and paint white over the area we want to add highlights. We pull up our Blend If dialog box and drag our bottom slider from left to right to start defining where our white Highlights will be visible. (Remember to Feather!) We now change the Blend Mode in our dialog box from Normal to Soft Light. This really helps us add definition to our image.
We use a similar technique when adding Shadows to our image. We create a New Layer and paint black over the areas we want Shadows. We adjust our sliders to our liking and also bring down our Opacity a bit. We are now able to see how the dark areas of the image are affected in comparison to the Highlighted areas.