I can't figure out what preprocessing of the image is needed before feeding it into the convolutional neural network. For example, I want to recognize circles on a 1000 by 1000 px photo. The learning process of a neural network occurs on 100 by 100 px (https://www.kaggle.com/smeschke/four-shapes/data). I'm having a little difficulty wrapping my head around the situation when the circle in the input image is much larger (or smaller) than 100x100 px. How then the convolution neural network determines that circle if it was learned on a dataset of a different picture's size.
For clarity, I want to submit a 454 by 430 px image to the network input:
Example of the dataset for the learning process (100 by 100 px):
Finally, I want to recognize all the circles on the input image: