PURPOSE: To shorten the time required for test of an image sensor by inputting picture data to a conversion table required for arithmetic processing to obtain data equivalent to the arithmetic processing result.

CONSTITUTION: Picture data read out from a first picture memory 10 is divided to upper bits and lower bits by a register 13, and upper bits are given to a Y address register 22 and lower bits are given to an X address register 21 to access an address position corresponding to the value of picture data. A converted value is read out from the conversion table by this access and is outputted to a register 24. That is, the conversion processing time of one data is very short and picture data of the image sensor having hundreds of thousands of picture elements is subjected to conversion processing in a short time because picture data is converted to a value equivalent to various arithmetic processing results by the conversion table. Thus, the time required for test of one image sensor is shortened, and many image sensors are tested in a short time.