An image processing device and method for convert multi-value image data having light and dark information per pixel into binary data for pseudo half-tone representation. A binarization results delay unit holds binarized data near the pixel of interest obtained by a binarizing unit, a slice value control unit calculates the amount of change in the slice value based on the concentration of the image or the binarized data pattern thereof, and determines the binarized slice value S based on the amount of change in slice value. The binarizing unit binarizing input image signals using the binarized slice value S. Thus, control of the amount of dot concentration in an arbitrary concentration area, and accurate control of texture can be realized.