An image processing apparatus includes a probability conversion unit, a processor, and a threshold conversion unit. The probability conversion unit receives an initial pattern and converts it into a probability distribution space. The processor performs weighting on a density distribution space indicating a density of pixels determined to be dotted using the probability distribution space, determines pixels to be dotted and an order of the dotting in the weighted density distribution space, updates the probability distribution space until the order for all pixels in the initial pattern is determined, and repeats the determination using the updated probability distribution space. The threshold conversion unit converts the order of dotting into thresholds to obtain a threshold matrix. The probability conversion unit uses a threshold matrix preliminarily created to form a halftone dot as the initial pattern.