1. A pathological diagnosis assisting apparatus for providing diagnosis assisting information from an image of a stained sample, comprising: an image reading unit configured to read the image of the stained sample; and an image processing unit configured to process the image of the stained sample, wherein the image processing unit includes: an image classification unit configured to, based on a pixel value of the image of the stained sample, classify at least one type of a specific substance serving as an index for detection of a lesion in the image of the stained sample, a tissue area extraction unit configured to extract a tissue area in the image of the stained sample, an image dividing unit configured to divide the tissue area into a plurality of equally sized sections, a specific substance occupancy rate calculation unit configured to, based on a result of classification of the image, calculate an occupancy rate of the at least one type of the specific substance in each of the plurality of sections, and a diagnosis assisting information providing unit configured to, based on the calculated occupancy rates in the plurality of sections, determine an intermediate value of the occupancy rate of the specific substance in the image of the sample and to provide the intermediate value as the diagnosis assisting information, wherein the determination of the intermediate value of the occupancy rate of the specific substance in the image of the sample comprises calculating the intermediate value by weighting the occupancy rate of the specific substance in each of the plurality of sections based on an area occupancy rate of the tissue area in each respective section where an occupancy rate of glass is less than a predetermined value, wherein the at least one type of the specific substance is a collagenous fiber.