Initial implementation of improved image sizes algorithm

[mukeshpanchal27]

Summary

Fixes #1187

[joemcgill]

Good start! I think it would be good to add some tests for these early on so we can make sure we're getting the output we expect.

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[joemcgill]

This looks like a good first implementation and tests well. I've left a few suggestions about improving the tests, but I think this is pretty close to merge so we have a base in the feature branch to work against.

[joemcgill]

One minor suggestion, but I think this is good. Pre-approving.