Two methods for display of high contrast images

High contrast images are common in night scenes and other scenes that inclu de dark shadows and bright light sources. These scenes are difficult to dis play because their contrasts greatly exceed the range of most display devic es for images. As a result, the image contrasts are compressed or truncated , obscuring subtle textures and details. Humans view and understand high co ntrast scenes easily, "adapting" their visual response to avoid compression or truncation with no apparent loss of detail. By imitating some of these visual adaptation processes, we developed methods for the improved display of high-contrast images. The first builds a display image from several laye rs of lighting and surface properties. Only the lighting layers are compres sed, drastically reducing contrast while preserving much of the image detai l. This method is practical only for synthetic images where the layers can be retained from the rendering process. The second method interactively adj usts the displayed image to preserve local contrasts in a small "foveal" ne ighborhood. Unlike the first method, this technique is usable on any image and includes a new tone reproduction operator. Both methods use a sigmoid f unction for contrast compression. This function has no effect when applied to small signals but compresses large signals to fit within an asymptotic l imit. We demonstrate the effectiveness of these approaches by comparing pro cessed and unprocessed images.