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Welcome to this lesson on Image Arithmetic, which is a not-often used option I think in the Image Menu. Let's open up a couple of images here; flag and then a sunset. And I'm going to choose the Image Menu and Arithmetic to get started. Image Arithmetic basically is one way of affecting images. It works sort of like the Blend Modes. What you do is select your images to work with, Image 1 and 2 here. Now, I can select from those that I have open. By default, it selects the two that I have open right now and loads them up into those menu selections. They are both the same size so my Alpha size is 1280 by 870, which is the same. Now, I can choose from different functions and different channels and then select different modifiers and so forth. It kind of can get complicated, but basically play around with it and see what you think. Functions are Adding, Subtract, Anding, Average, Multiply, Difference or Darkest, Lightest or X Or. And those are mathematical, hence the term arithmetic, mathematical operations on the color values or the brightness values of the pixels and it basically, it starts at one corner and goes through every pixel of the image and says OK, I'm going to add these to together. What is the color value of Image 1 and I'm going to add it to the value of Image 2 and it goes from each channel here. I can choose All Channels or specify a specific channel. So let's select All Channels so every pixel is going to be added together. I'm going to select OK and then we can see the result on a third image which essentially added the pixel values together. So I've got the flag overlaid on this sunset, which is very interesting. I don't know if you'd ever want to use that, but let's choose Image Arithmetic and choose something else. Now we're going to Subtract. OK. There; completely different effect. Instead of adding the values together, it subtracted them and that looks pretty interesting. And in continuing on down the line, you can choose to affect one channel of one versus a different channel in the other or the same channel. Let's say I want to take Image 1's green channel and multiply it by Image 2's blue channel. And select OK and that's what I get. Now, I wouldn't have predicted that's what would happen. In fact, in Arithmetic, it's almost impossible to do that really beforehand, but it's an interesting effect nonetheless. And I think that's probably why a lot of people, you know, don't use it or wouldn't use it because sometimes it's hard to predict. It's hard to guess what you're going to get. You can kind of try to reason it out in your head but it's actually far easier and simpler just to keep going through these. OK. So that's, those are those two images. So let's open up two different ones; grasshopper and a P-51. Image Arithmetic; notice that the images are loaded here, Image 1 and 2. I'm going to choose Darkest this time, All Channels. OK. You see the grasshopper loaded up there. It might actually be better to close the grasshopper and put the flag up here and see if we can overlay these together. Image Arithmetic, I'm going to do X Or just to be unique, press OK, kind of a very psychedelic approach. Got the flag and you can clearly see the outlines of the flag and then the aircraft. That's pretty neat. Might be able to put that on a web page or post it as just a pure, purely artistic creation. Average, let's look at that. That's more like a transparent overlay of just averaging those pixels together. That's pretty interesting too. Each time I'm closing out the image that was created, OK? So that's basically, the mechanics are very simple. You choose your two images, you select the function that you would like to implement, you decide the channels that you want to affect between Image 1 and 2 or All Channels and now the, kind of the harder things, Divisor or a Bias, we can set those 45 and minus 107 and try averaging all channels again and see what we get. Well, we get black. OK, that one didn't work. These settings, going to have to, let's change Bias to 0 and Divisor 45 and see what we get. We get more black. OK. So you can see that those are kind of hit or miss. Let me try something else here. Twelve and twenty-six. That's more of a dark gray. Very muted. You can still see the colors of the flag but the aircraft was black and white or grayscale pretty much anyway. Alright. I hope, I hope this lesson was valuable to you. Don't forget about this. It's very creative. It's somewhat unpredictable but experiment with it and add it to your bag of tricks or things to try when you want something really unique and different. There may be other practical purposes to it as well. Averaging or selecting the lightest pixel of images to try to darken or lighten certain areas, you could enter different exposure values of the same image and mess around with it like that. But basically this should be enough to get you started playing around with it.