Optimize multiple crops

[paulnovo]

Update CroppedProjectiveTranform to optimize projective transforms followed by multiple crops, not just one crop. For instance:

Rotate(10) |> CenterCrop((100, 100)) |> RandomCrop((50, 50))

Is now optimized to warp only into the 50x50 region, instead of to the 100x100 region.

One caveat of this implementation is that crops that enlarge the region after a smaller crop will be different due to extrapolation of the smaller crop being skipped. ie this will give different results now:

Rotate(10) |> CenterCrop((50, 50)) |> RandomCrop((100, 100))

I wonder if enlarging crops should be disallowed anyways, since offsetcropbounds doesn't appear to be written with it in mind (ie sz>bounds), unless I am missing something. Thoughts?

PR Checklist

• Tests are added
• Documentation, if applicable