An image forming apparatus includes a setting unit configured to set an operation mode, and a processing unit configured to perform image processing on image data according to the operation mode. In a case when a first mode is set, the image processing includes determining, in the image data, one or more target pixels having a gradation value equal to or higher than a first threshold value, and one or more adjacent pixels that are different from the one or more target pixels and adjacent to the one or more target pixels, setting a first gradation value lower than the first threshold value as a gradation value of the one or more target pixels, and setting a second gradation value higher than the first gradation value as a gradation value of the one or more adjacent pixels.