1. A still image generation method of generating a relatively high-resolution second image from multiple relatively low-resolution first images, the still image generation method comprising the steps of: (a) estimating a correction rate for elimination of a positional shift between the multiple first images; and (b) executing correction with the estimated correction rate to eliminate the positional shift between the multiple first images and combining the multiple corrected first images to generate the second image, the step (b) comprising the steps of: (b1) selecting a target pixel among pixels included in the second image; (b2) detecting multiple adjacent pixels respectively in the multiple first images, which adjoin to the selected target pixel; and (b3) selecting a composition object image with regard to the target pixel among the multiple first images according to the multiple adjacent pixels, and calculating a pixel value of the target pixel based on the composition object image, wherein the step (b3) selects one base image from among the multiple first images when selecting the composition object image among the multiple first images, determines whether or not the multiple adjacent pixels in the multiple first images other than the base image have a motion relative to the base image, and if it determines that a certain adjacent pixel out of the multiple adjacent pixels has a motion, the step (b3) excludes the first images including the certain adjacent pixel from the composition object image with regard to the target pixel, wherein the step (b3) comprises the steps of: (b31) when the first image including a nearest pixel having a shortest distance to the target pixel among the multiple adjacent pixels is the base image, calculating the pixel value of the target pixel based on the base image, and (b32) sequentially selecting an adjacent pixel that is not included in the base image among the multiple adjacent pixels in an order closer to the target pixel and detecting motion or no motion of the selected pixel relative to the base image, the step (b31) calculating the pixel value of the target pixel based on the first image including the selected pixel detected as a pixel with no motion, while calculating the pixel value of the target pixel based on the base image when every selected adjacent pixel is detected as a pixel with motion, and wherein each of the steps of the still image generation method is executed by a processor.