In this lesson, we learned about tracker.
2D tracker that allows you to extract animation data from the position, rotation, and size of an image. Using expressions, you can apply the data directly to transform and match-move another element. Or you can invert the values of the data and apply them to the original element – again through expressions – to stabilize the image.

Combine alpha
Channelmerge
The ChannelMerge node lets you merge together one channel from each input and save the result in the selected output channel. All other channels are copied unchanged from the B input.
If no A input is connected, both channels to merge are taken from the B input.
By default, ChannelMerge combines the inputs’ alphas.

Grade (pressing G on Node Graph)
Lets you define white and black points by sampling pixels from the Viewer. Setting the brightest parts of the image to pure white and the darkest to pure black in this manner can help you add punch to overexposed images, for example. You can also use this node for matching foreground plates to background plates.
To sample pixels from the Viewer, click on a color swatch to the right of the control you want to set. The eye dropper icon appears. In the Viewer:

- Ctrl/Cmd+click to sample a single pixel from the node’s output.
- Ctrl/Cmd+Shift+drag to sample a region of pixels from the node’s output.
- Ctrl/Cmd+Alt+click to sample a single pixel from the node’s input while viewing its output.
- Ctrl/Cmd+Alt+Shift+drag to sample a region of pixels from the node’s input while viewing its output.
- Crtl/Cmd+ right-click cancels pixel selections.
Clamps
This node constrains, or clamps, values in the selected channels to a specified range. By default, it clamps all channels to values between 0 and 1. This can be useful for ensuring that the input’s blackest blacks and whitest whites will be visible on an intended display device, or for restricting data fed to a subsequent node that does not support numbers outside this range.

Reformat

Keymix
Keymix for green screen key:IBKcolor(A)+primatte(B)+roto(Mask)
