1. A computer-implemented method for displaying a portion of a high-resolution image in the context of a base-resolution image, wherein one or more processors of a client device are programmed to perform the steps comprising: sending a request to a server over a network for an image; receiving the image from the server over the network; generating a base-resolution image from the received image; displaying the base-resolution image on a display; receiving a request to display an area of interest of the base-resolution image in high resolution; sending a request to the server over the network for a high-resolution image that corresponds to at least the area of interest of the base-resolution image; receiving the high-resolution image from the server over the network; displaying at least a portion of the high-resolution image corresponding to the area of interest as an overlay of the base-resolution image at a location that corresponds to the area of interest, wherein the overlay comprises a virtual lens; tracking movements of a cursor controlled by a pointing device over the base-resolution image; moving the virtual lens with respect to the base-resolution image based on a location of the cursor relative to the base-resolution image; and updating the at least a portion of the high-resolution image displayed by the virtual lens based on the location of the cursor relative to the base-resolution image, wherein the base-resolution image and the high-resolution image each comprise one or more images.