An image processing device includes a multiplier 1 for multiplying a pixel signal P(x) by a weighting factor α0 (0≦α0≦1), a delay element 2 for delaying the pixel signal P(x) which has not been multiplied yet by the weighting factor α0 by the multiplier 1 by one pixel, and a multiplier 3 for multiplying the pixel signal P(x−1) delayed by the delay element 2 by a weighting factor α1 (0≦α1≦1), the total sum of the weighting factors α0 and α1 being larger than 1 and smaller than an upper limit αmax. An adder 4 adds the multiplication result α0·P(x) of the multiplier 1 and the multiplication result α1·P(x−1) of the multiplier 3, and a limiter 5 limits the addition result P′(x) of the adder 4 in such a way that P′(x) falls within a maximum density value Pmax.