Photoshop Tutorials |

I have three layers. The first one is my image through a filter. The second is the actual image with a "reveal all" layer mask. The third and bottom layer is an image that I want a partly revealed in my 2nd layer. How do I get my second layer to "reveal" the third image without the third image being affected by the first layer (the filter).

Do I lock the third layer so that it's not affected by the first layer? Or do I restack the layers?

Hm, by "through a filter" do you mean an Adjustment Layer with a Photo Filter? If that's the case, select the adjustment layer, right click on it and select Create Clipping Mask. You'll see the layer icon indent indicating that it is only applying to the layer directly below it.

If it isn't what you mean, I'm missing something in your question.