ERROR DETECTING APPARATUS

A least square calculating circuit receives a plurality of past normal pixel data and class information. The calculating circuit predicts future pixel data corresponding to a linear coupling of the past pixel data and the coefficients for a class. At this time, the calculating circuit determines coefficients where the square of an error becomes minimum. The learnt coefficients are stored in a coefficient memory. An estimation value generating circuit generates an estimated value corresponding to the coefficients and the past pixel data. A subtracting circuit generates a difference value between the estimated value and the real value. The difference value is supplied to an error determining circuit. When the difference value largely deviates from the estimated value and when the number of such pixels that take place in a predetermined time period is larger than a predetermined threshold value, an error is detected.