To provide an image processing apparatus, an image processing program, an image processing method, and a microscopic system that are capable of acquiring a high-resolution image that is suitable for scientific verification.An image processing apparatus according to the present technology includes an image conversion unit and an image generation unit. The image conversion unit converts a first picked-up image and a second picked-up image into frequency components, the first picked-up image being obtained by picking up an image of an observation target object with first illumination light via a microscope optical system, the second picked-up image being obtained by picking up an image of the observation target object with second illumination light via the microscope optical system, the second picked-up image having a contrast in a low frequency band lower than that of the first picked-up image and a contrast in a high frequency band higher than that of the first picked-up image. The image generation unit combines a low frequency component of the first picked-up image and a high frequency component of the second picked-up image with each other to generate a composite image.