Patent ID: 8237991

Claim:
An image processing apparatus comprising: an acquiring unit configured to acquire a print characteristic based on at least one of information indicating the type of a print medium used to print and information indicating the type of ink used to print; a region setting unit configured to set a region configured by a plurality of pixels in image data, the plurality of pixels including a pixel of interest, and each of the plurality of pixels having signal values corresponding to a plurality of colors; a brightness value derivation unit configured to derive, for each of the plurality of pixels, a brightness value from the signal values corresponding to the plurality of colors; a first determination unit configured to determine an edge direction of the set region based on the brightness values for the plurality of pixels within the set region, wherein the first determination unit determines the edge direction by: deriving a first derivative of the brightness value at the pixel of interest in each of predetermined directions based on the brightness values for the plurality of pixels within the set region; selecting a direction which has a maximum first derivative from among the predetermined directions; a second determination unit configured to determine a replacement candidate pixel from among the plurality of pixels which include the pixel of interest and line up in the edge direction based on the brightness values for the plurality of pixels and the print characteristic, wherein the second determination unit determines the replacement candidate pixel by: deriving a second derivative of the brightness value at the pixel of interest based on the first derivative; and correcting the second derivative based on the print characteristic; and a replacement unit configured to replace the signal values of the pixel of interest by a replacement signal value calculated based on at least one of the signal values of the replacement candidate pixel and the signal values of the pixel of interest.