For cases where we want to batch process an image into multiple versions, it's fairly straightforward if only changing the scale. But if we want to vary the cropping things get complicated. This is because using the Scale node's Crop mode on either Render Size or Scene Size. Neither of these values can have multiple instances or be key-framed to change over time.
In the screen shot above, the resizing (cropping) only works correctly because the Render Size is set correctly.
But this can only be done once. Even if we create another scene with different render dimensions, only the current scene gets used by the Scale node.
Using the Scale node in Absolute mode causes stretching instead of cropping.
It seems like there should be a way to do this. Am I overlooking something?
Update: I've made some progress with the size by using a Translate node followed by a Crop node, but the crop is off-center.