PURPOSE: To make a pattern accurately and quickly by altering the contents of a frame memory with the addition or elimination of indication dots specified at points assigned as requiring correction.

CONSTITUTION: A dot structure of a pattern is assigned with a key board 6. A pictured image signal PS from a TV camera 2 is converted into a digital signal DP corresponding to black and white on an original pattern so as to be memorized and indicated on a CRT display device 7. When a correction is needed in the observation of the pattern displayed on the display device, a light pen contacts a point MP requiring correction and the addition or elimination of dots 73 and 74 are specified on the pattern with a correction button 12. The addition or the elimination of the data indicated is performed for the data stored in a frame memory 4 through a CPU5. When the output is assigned on the keyboard 6, the data displayed is formatted in an output in a format and stored in a storage device 8.