PURPOSE: To ensure free selection of the scanning direction and to facilitate the easy electric processing for picture of an optical image, by providing horizontal and vertical reading circuits which are set backward to each other for free selection of the reading direction.

CONSTITUTION: A horizontal clock pulse 7, a horizontl transfer clock pulse 8 and a horizontal start pulse 9 are applied to a horizontal shift register 19 as well as a horizontal shift register 4. However the register 19 has its transfer direction adverse to the register 4 for scanning to obtain a signal output 6. Therefore the signal of each photodetecting diode is read out and scanned backward for the output signal 6. This obtains a picture which is adverse symmetrically to the image of a object. In the same way, a vertical shift register 24 has its transfer direction opposite to a vertical shift register 5 for scanning. Thus a picture which is adverse vertically to the object image. These pictures are selected with a switch among input control signals 17, 18, 21 and 25 respectively.