In my case we allow up to 10mb file upload. For example just testing something right now from my iPhone I selected a 3.7mb image which was uploaded and resized to the "frame" it will go into in the UI and its now 288kb in S3. We have a few "frame" sizes which are consistent throughout our application. Now, my cloudfront is serving 288kb file instead of 3.7mb, which is good for me because I want to avoid the bandwidth costs and users honestly can't tell the difference, and then also we aren't a photo gallery app.

So in my case I need the lambda to resize the image to our "frame" sizes. I wonder if I didn't explain right. I'm ESL so just want to make sure since I'm confused about the your last sentence.