When used for image recognition, convolutional neural networks (CNNs) consist of multiple layers of small neuron collections which look at small portions of the input image, called receptive fields. The results of these collections are then tiled so that they overlap to obtain a better representation of the original image; this is repeated for every such layer. Because of this, they are able to toleratetranslation of the input image.[4] Convolutional networks may include local or global pooling layers, which combine the outputs of neuron clusters.[5][6] They also consist of various combinations of convolutional layers and fully connected layers, with pointwise nonlinearity applied at the end of or after each layer.[7] It is inspired by biological processes. To avoid the situation that there exist billions of parameters if all layers are fully connected, the idea of using a convolution operation on small regions has been introduced. One major advantage of convolutional networks is the use of shared weight in convolutional layers, which means that the same filter (weights bank) is used for each pixel in the layer; this both reduces required memory size and improves performance.[3]