If you took one of those, and read the signals in a location that you photographed, could you then convert the oscilloscope signals into a color representation, then layer that image over the top of the visual photo layer?

Yes. You can do ANYTHING in photoshop. It's just a matter of setting your mind to it, and learning the program. I'm a big believer in "learn by doing." Don't go and sit and do 40 hours of photoshop because you want to learn. Go and learn the exact skills in order to accomplish at hand and you will learn 4 times as much in those 40 hours.

So here's your background landscape, whatever:

Now to add a layer, you can add another photo, or a shape, or a graphic or whatever you want.

I made a circle.

Here's the circle with a 50% opacity and a variety of "blending modes"

You change those in the little boxes above the layer panel.

Now if you want to play with the levels you go to the adjustments layer and you can edit the whites, grays, and blacks. And the reds, greens, and blues, individually. This is how you color correct images. You want the whites to be true white (255,255,255) and blacks to be true black (0,0,0)

You can use color sampler to look at the individual numbers of red/green/blue - look in the upper right at the numbers.

Using the levels adjustment layer to edit the levels.

You can also fuck with them to do all sorts of crazy things, like making something really blue or red.

Those levels are a new layer that affect all layers below it. Or you can set it to only affect a certain area. Same goes for all the adjustment layers in photoshop: photo filters, hue, saturation, lightness, etc.

So you can have essentially an unlimited number of layers. These layers can be photos, shapes, graphics, anything! And you can edit the color, blend and other things like shadow, glow, texture, etc. all individually.

This is super super basic and doesn't go into much at all. Let me know what you want me to elaborate on - I could write an essay about any of these things.