1. A halftone image generation device that, by partially selecting and blending a first halftone image obtained by halftone processing a specific image using a first method and a second halftone image obtained by halftone processing the specific image using a second method that differs from the first method, generates a third halftone image of the specific image, comprising: a detector configured to detect from the first halftone image, a pixel of interest in which a dot is disposed; and a blender configured to blend the first halftone image and the second halftone image by, in a case where dots are not disposed in neighboring pixels of the pixel of interest in the first halftone image, employing, as binary values of isolated-point related pixels in the third halftone image that are in a same position as the pixel of interest and the neighboring pixels, binary values of the pixel of interest in the first halftone image and the neighboring pixels in the first halftone image.