Image Arithmetic
Add Example - Reflection

I hope that the preceding examples gave you a little bit of a feel for how addition works, and how the divisor and bias influence the results. Now let's try to do something a little more useful.

This is a really nice picture. Kinda hard to see how a person could improve on Mother Nature. But nothing says we can't have fun with her.

What I wanted to do here was to leave the top portion of the picture untouched, but to experiment with the reflections on the water. Since black is (0,0,0), adding black has no effect when your divisor is 1 and your bias is zero. What I needed was a picture that was black on top and some sort of texture on the bottom.

I had a background image that I thought might be used for some interesting effects. After resizing it to the same size as the scenery picture, it looked like this.

I placed the background image next to the scenery one, and used the rectangular select tool to select the top portion above the water. Then I set the background to black and hit the delete key. Voila!

Now let's experiment a bit.

Add — divisor 1 bias 0

Original #1
Original #2
Add — d=1, bias 0

As I expected, this result is much too light. But I couldn't use either of the methods normally used to improve the result (divisor=2 or negative bias) without affecting the top part.

Darkened 2nd Image

Original #1
Original #2 (darkened)
1st result
New result

So what I did was darken the 2nd image. I used Color | Brightness to darken the texture considerably.

Much better! It's beginning to look interesting. But I don't care much for the transition area.

Smudge

Before smudge
After smudge

I used the smudge brush to try to improve the transition.

Gamma Correction

Original
Before smudge
After smudge
After gamma

The reflection area was still a bit too light, so I applied some gamma correction to that area.

Other Effects

Now I'm just experimenting with various PSP effects. Here, I've applied Image | Edge | Enhance.


Undoing the edge enhance, I've now applied Image | Edge | Find all.


Undoing the edge find, I've now applied a hot wax coating using a pale yellow foreground color.


Undoing the hot wax, I've now applied the Pool Shadow filter from Filter Factory A.