An image processing apparatus for reshaping a threshold matrix defining halftone dots, the apparatus comprising: a probability conversion unit that receives an initial pattern and converts the initial pattern into a probability distribution space that indicates the probability of dotting for each pixel in a screen process using a threshold matrix; a processor having a weighting calculation unit, a dotting unit and an updating unit, the processor configured to perform weighting on a density distribution space by the probability distribution space, the density distribution space defined as an image space with m × n pixels showing the density of pixels determined to be dotted, with the initial value for each pixel being "1", determining, in the weighted density distribution space, pixels with the highest value as the pixels to be dotted and forming a dotting space (Ig) with m x n pixels indicating that the pixels determined to be dotted have been dotted, such that if a pixel has the highest value in the density distribution space and the pixel is already dotted in a preceding step, the dotting unit excludes the dotted pixel in the dotting space (Ig) and determines pixels to be dotted and the dotting unit forms a dotting-order space (Num) with m x n pixels indicating an order of dotting of the pixels to be dotted, and updating by the updating unit the probability distribution space by performing a weighting calculation on the probability distribution space in accordance with the position of the latest dotted pixel in the dotting space (Ig) and providing an inverted and low-pass filtered dotting space (Ig) as a density distribution space for use in the second repeating process, and repeating the determination of the pixels to be dotted and the order of dotting using the updated probability distribution space until all the pixels are dotted in the dotting space (Ig), and the dotting-order space (Num) indicating the order of dotting for all the pixels is obtained; and a threshold conversion unit that converts the order of dotting of the pixels (Num) determined by the processor into respective thresholds to obtain a threshold matrix (THnew), wherein the probability conversion unit uses a threshold matrix (THdef) preliminarily created to form a halftone dot as the initial pattern. a probability conversion unit that receives an initial pattern and converts the initial pattern into a probability distribution space that indicates the probability of dotting for each pixel in a screen process using a threshold matrix; a processor having a weighting calculation unit, a dotting unit and an updating unit, the processor configured to perform weighting on a density distribution space by the probability distribution space, the density distribution space defined as an image space with m × n pixels showing the density of pixels determined to be dotted, with the initial value for each pixel being "1", determining, in the weighted density distribution space, pixels with the highest value as the pixels to be dotted and forming a dotting space (Ig) with m x n pixels indicating that the pixels determined to be dotted have been dotted, such that if a pixel has the highest value in the density distribution space and the pixel is already dotted in a preceding step, the dotting unit excludes the dotted pixel in the dotting space (Ig) and determines pixels to be dotted and the dotting unit forms a dotting-order space (Num) with m x n pixels indicating an order of dotting of the pixels to be dotted, and updating by the updating unit the probability distribution space by performing a weighting calculation on the probability distribution space in accordance with the position of the latest dotted pixel in the dotting space (Ig) and providing an inverted and low-pass filtered dotting space (Ig) as a density distribution space for use in the second repeating process, and repeating the determination of the pixels to be dotted and the order of dotting using the updated probability distribution space until all the pixels are dotted in the dotting space (Ig), and the dotting-order space (Num) indicating the order of dotting for all the pixels is obtained; and a threshold conversion unit that converts the order of dotting of the pixels (Num) determined by the processor into respective thresholds to obtain a threshold matrix (THnew), wherein the probability conversion unit uses a threshold matrix (THdef) preliminarily created to form a halftone dot as the initial pattern.