Why is the Input image not resized to same size ?

[Susiehub]

After loosely cropping the input images, I see that the cropped images have different sizes. And they are not resized to the same size. Am i correct?

If yes, Is there any particular reason for the input images not being the same size ? and is it okay to give the Resnet50 different image sizes ? I ask this Question because I assumed Input for Resent50 should be of size 224x224x3.