Special Konversatorium on Monday, September 22, 2003 - 15:00

The status of the current output devices as: display and printers, limit to visualize or print correctly High Dynamic Range images. Tone mapping helps to resolve this problem, but when accurate visualization is requested local operators are required. Local operators are able to capture this goal, but they require high computational costs that reduce their use in real applications. In this talk we propose a speed-up technique in order to reduce the computational costs of an existing local operator derived by retinex. It consists to extract both: global and local information from the existing operator and to extrapolate it on the whole image. We show how to extract the global information sampling the input image and using singular value decomposition (SVD). On the other hand, the local information is extracted selecting a small number of samples for each pixel of the input image and applying directly the local operator. We show the efficiency of our method on several images, and the time performances comparing it with the original local operator.