1. A method of improving image quality of an image obtained by imaging a sample with a scanning charged particle microscope, the method comprising: a scan step of imaging the sample while scanning and irradiating some regions of the sample within an imaging visual field of the scanning charged particle microscope with a focused charged particle beam, so as to sequentially acquire image data of the sample; a region dividing step of dividing a region in which the image data is acquired into two or more regions among regions within the imaging visual field of the scanning charged particle microscope which sequentially acquires the image data in the scan step, on the basis of a distance from a region in which the image data is not acquired; a processing method and processing parameter determining step of determining an image quality improvement processing method and a processing parameter for image quality improvement according to the regions obtained through the division in the region dividing step for the image data in each of the separate regions; an image quality improvement step of performing an image quality improvement process on the image data in each region obtained through the division in the region dividing step by using the processing method and the processing parameter corresponding to the separate region, determined in the processing method and processing parameter determining step; and an image quality improvement result display step of displaying an image having undergone the image quality improvement process in the image quality improvement step, wherein steps from the scan step to the image quality improvement result display step are iterated until scanning of a region of the sample within the visual field of the scanning charged particle microscope is completed.