ok, here is the thing, if you don't want to rescale or crop. then you won't be able to do the batch processing.
you can scale your input image to one size. just make sure that all your training images are of the same size and similar transformations needs to be done to your ground truth (bound box).
Big problem: I don't wanna apply the transformation to the bounding box and it's complex to do?
Here is a simple library Albumentations that can do all that for you. you need not to worry about the maths-
Library - https://github.com/albumentations-team/albumentations
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…