How to create a color difference key

- [Teacher] In the previous video,…we saw strategies for pulling a key from a single channel.…Here, we'll kick it up a notch…and make more discriminating keys…by using the difference between two-color channels…such as green minus red, for example.…This is a surprisingly powerful technique…that can produce some very nice keys…with just a few minutes of work.…Now this is a basic color difference key setup.…The idea is, you can just walk through here…and see all the different channel arithmetic operations.…

The idea is we always start with a de-noise node…to get rid of the noise to make for cleaner keys.…These are just shuffle nodes where I have shuffled…the entire red channel into this data stream.…So I now have a red image, a green image, and a blue image…so that I can use merge nodes instead of the channel merge.…This just makes it easier to follow the process.…At the end, we'll redo it with channel merge nodes.…So we have all possible combinations.…

Here is what red minus blue looks like, red minus green,…green minus red, green minus blue,…