PURPOSE: To decrease as a whole the storage capacity of a storage means, and also, to efficiently execute a read-out processing by storing binarization image information being color information and variable density image information being brightness information, in a lump as one image data.

CONSTITUTION: A red signal and a blue signal of color signals separated by an NTSC decoder 2 are brought to a subtraction processing by a color separating circuit 3, and also, binary-coded by a binarization circuit 4, and converted to binarization image information S4 which has extracted a specific color area corresponding to only a color of a fruit to be recognized. On the other hand, a luminance signal is quantized by an A/D converter 5 and converted to variable density image information S5, synthesized with the information S4 at every quantized picture element unit by a data buffer 6 and stored as image information of one screen portion. In such case, an image data S6 per one picture element is expressed by 8 bit length, and its lowest bit position and the remaining 7 bit portion are used as a value of the information S4 and a value of the information S5, respectively. Accordingly, binarization color information and brightness information corresponding to every quantized picture element shown by 8 bit length are stored as the data S6 in the same address position in the memory 7.