| 摘要 |
<p>A document reading apparatus includes average output value detecting circuits and random value generating adder/subtractor circuits. The average output value detecting circuits detect and hold the average output values of the pixels of the FO, FE, LO, and LE outputs, respectively. The random value generating adder/subtractor circuits each has a function of randomly generating any value between 0 and 1, and performs an arithmetic operation on all the pixels of the LO outputs, using the following equation: <DF>Dout = ROUND (Din - 0.5 + RAND + a) </DF> where: ROUND represents a round-off function for rounding off a decimal point or below; RAND represents a random number that is renewed for each pixel; and a represents the difference in average value, which is 1.5 in this case. <IMAGE></p> |
