An image processing apparatus, an image processing method, and an image processing program which are provided with a robustness capable of dealing with differences in environment where images are captured and a high-speed performance capable of processing a large number of images for a short time are provided. For this purpose, with respect to a body cavity image captured inside a living body, a pixel value change amount of a pixel of interest with a plurality of surrounding pixels located around the pixel of interest and a surrounding pixel value change amount between the plurality of surrounding pixels are calculated a candidate lesion region in the body cavity image is detected based on a calculation result by a change amount calculator and on a calculation result by an inter-surrounding-pixel change amount calculator then a feature of the detected candidate lesion region is extracted and a lesion region is detected from the candidate lesion region based on the extraction result.
