Convolutional Neural Network – Towards Data Science

Convolutional Layer is the first layer in a CNN. It gets as input a matrix of the dimensions [h1 * w1 * d1], which is the blue matrix in the above image. Next, we have kernels (filters). A kernel is a matrix with the dimensions [h2 * w2 * d1], which is one yellow cuboid of the multiple cuboid (kernels) stacked on top of each other (in the kernels layer) in the above image. For each convolutional layer, there are multiple kernels stacked on top of each other, this is what forms the yellow 3-dimensional matrix in Fig 2, which is of dimensions [h2 * w2 * d2], where d2 is the number of kernels.