A class activation heatmap is a spatial grid showing which image locations support a model’s prediction for a chosen class. It helps interpret classification decisions, debug mistakes, and locate objects. section 10.3
Grad-CAM builds the heatmap from a convolutional layer’s output: it weights each feature-map channel by the class gradient, then combines the weighted channels into a spatial activation map. section 10.3
African elephants
For an image containing two African elephants, the model predicts African elephant with high probability. The resulting heatmap highlights elephant regions; strong activation around the calf’s ears suggests a feature supporting the distinction from Indian elephants. section 10.3.4

