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 that detects, from the first halftone image, a dot pixel in which a dot is disposed; and a blender that blends the first halftone image and the second halftone image by, in a case where a dot is not disposed in any of neighboring pixels in the first halftone image that neighbor the dot pixel, employing, as binary values of isolated-point related pixels in the third halftone image that are in a same position as the dot pixel and the neighboring pixels, binary values of the dot pixel and the neighboring pixels.