An imaging system for providing high resolution ratio of images under a low cost includes a visible light image module, an infrared image module, and a processor. The visible light image module generates a visible light image. The infrared image module generates an infrared image. The processor executes following processes: acquiring a visible light image and an infrared image; transforming the visible light image and the infrared image into visible light image spectrum information and infrared image spectrum information respectively; acquiring high frequency information from the visible light image spectrum information; merging the high frequency information and the infrared image spectrum information to obtain merged image spectrum information; and transforming the merged image spectrum information into a merged image. An imaging method and a computer readable storage medium are also disclosed.