PURPOSE: To reduce the cost, to decrease an input processing time and to facilitate the discrimination of pattern borders by selecting data in a range close to a brightness of a position in response to color designation of data and applying file processing to hue patterns.

CONSTITUTION: The operator uses a mouse 16 to point an intermediate gray part (actually in red color) on a cursor indicated on a display screen of a monitor 14 and sets a value of picture data at that point to be, e.g. 150. Then the entire data stored in a picture memory 13 are sequentially read and when the data are within the range of ±10 (140-160) of the inputted value, the data are recognized to be red and it is replaced with the value 150. Then a color sample is displayed on one corner of the display screen of the monitor 14, the same color as that of an original is pointed by a cursor on the monitor 14 and the pattern data together with the color number are filed, then red color data are formed. In this case, a difference of brightness is emphasized by using a color filter to facilitate the discrimination of borders of the patterns.