Convolutional neural networks can be used for image recognition on mobile devices. The document discusses using Keras and TensorFlow to train a CNN model for digit recognition, then deploying it to iOS using CoreML. It also covers improvements to CNN models like VGGNet, Inception, ResNet, and MobileNets which use techniques like convolutions, max pooling, parallel execution and depthwise separable convolutions to improve accuracy while reducing model size and complexity. The document provides examples and code links for demos of these CNN models running image recognition tasks on mobile.