In order to realize a neural network for image processing by an inexpensive hardware arrangement, a neural network arranged in an image processing apparatus is constituted by an input layer having neurons for receiving information from picture elements in a 7.times.7 area including an interesting picture element in an image, an intermediate layer having one neuron connected to all the 49 neurons in the input layer and five groups of nine neurons, the nine neurons in each group being connected to nine neurons in the input layer, which receive information from picture elements in at least one of five 3.times.3 areas (1a to 1e), and an output layer having one neuron, which is connected to all the neurons in the intermediate layer and outputs information corresponding to the interesting picture element.