thanks for your ansewr.
say I want to have an output layer that has the half size of the original (pretrained) one. does not this allow me to tweak the stride value to 2 instead of the oraginally value 1 ?
you also mentioned that pretrained layers are trained to deal with specific spatial size. does this mean if vgg16 for example was trained on 224 by 224 images then we can input only this image size?