1. A diagnosis support apparatus of diagnosing a lesion based on a captured image, comprising: a processing unit configured to process the captured image composed of multivalued image as an original image; and an image-memorizing unit configured to memorize the original image, wherein the processing unit performs: a first generation processing of performing a bottom-hat closing processing in a morphology processing for detecting a dark portion based on the original image memorized in the image-memorazing unit, to generate an image (A); a second generation processing of performing a top-hat opening processing in a morphology processing for detecting a bright portion based on the original image, to generate an image (B); a first extraction processing of performing a smoothing filter processing on the image (A) and subtracting the image (A) from a smoothing filter-processed image (A) to extract a candidate region, when acquiring a shape from a low pixel value of the original image; and a second extraction processing of performing a smoothing filter processing on the image (B) and subtracting a smoothing filter-processed image (B) from the image (B) to extract a likelihood of a region, when acquiring a shape from a high pixel value of the original image.