PURPOSE: To improve speed for random scan by providing a storing order storing means to store a storing order in advance corresponding to the scanning direction of a picture and a picture signal storing means to store the digital signal of the picture based on the storing order.

CONSTITUTION: A table memory 6 is provided to store the storing order in advance corresponding to the scanning direction of the picture, and a scan data memory 8 is provided to store the digital signal of the picture to be obtained from a binary circuit 3 based on the storing order to be stored in the table memory 6. Then, a feature extraction circuit 11 is provided to extract a prescribed feature amount based on the digital signal of the picture to be stored in the scan data memory 8. Accordingly, when the picture is scanned at random, it is not necessary to calculate an address for storing the signal of the picture to be scanned. Thus, the random scan of the picture can be executed at high speed.