A tensor is a structured array of values. In image processing, a rank-3 tensor has height, width, and depth (channels), organizing spatial data and learned features. section 8.1.1
From image to feature map
An RGB image can have shape (height, width, 3), because its depth contains red, green, and blue channels. A convolution can transform an MNIST input of shape (28, 28, 1) into (26, 26, 64): the first two axes remain spatial, while 64 output channels represent learned filters. Each channel forms a response map showing where its pattern appears. section 8.1.1
Figure 8.3 The concept of a response map: a 2D map of the presence of a pattern at different locations in an input
Use the response-map figure to visualize a depth channel as a two-dimensional map of a pattern’s presence across image locations. section 8.1.1






