In a case where a dot forming condition is not satisfied, whether to form a dot for a target pixel is determined according to a predetermined method and dependently on a colorant-corresponding gradation value for the target pixel. The colorant-corresponding gradation value for each pixel is defined for a color component corresponding to colorant and representing density of the color component in color of the each pixel. The dot forming condition includes that the target pixel is an edge pixel and that a density index value for the target pixel, which is related to density of the color component in the color of the target pixel that is represented by the colorant-corresponding gradation value, is greater than a threshold value. In a case where a dot forming condition is satisfied, it is determined that a dot is to be formed for the target pixel, irrespective of the colorant-corresponding gradation value.