A composite imaging method has been developed that enables the user to directly capture a composite image by one-image capturing. It was experimentally verified that the composite images of bright-field, dark-field, and phase-contrast images can be captured with an arbitrary composition ratio. The difference in pixel values between the captured composite image and the computer composite image was small. This imaging method is realized only by placing below the condenser a masking plate, which can easily be made using Neutral Density filters. Therefore, little additional time and cost are needed. The composite imaging method was applied for extracting Helicobacter pylori in microscopic images of HE-stained gastric histological sections. H pylori is difficult to extract because the colors in H pylori are similar to those in other areas. It is experimentally shown that a composite image of phase-contrast and dark-field images captured using the proposed method improves the accuracy for extracting H pylori.