1. An image display device comprising: a display circuitry configured to display pathological slide images having different resolutions, pathological index layers and index lists for the pathological index layers; a display combining circuitry configured to receive one of the pathological index layers that has a related pathological slide image and overlay said one of the pathological index layers over the related pathological slide image based on a resolution of the related pathological slide image to form a combined pathological slide image.