Real-Time Adaptive Radiometric Compensation

Our new radiometric compensation algorithm considers the human visual perception properties to reduce visible artefacts resulting from the limited dynamic range and brightness of projectors. It preserves a maximum of luminance and contrast and is implemented entirely on the GPU. Real-time frame rates are achieved for supporting animated and interactive content. Initially our algorithm performs an off-line analysis of the projection surface's geomety and reflectance. The image content is then analyzed to determine the average luminance values, the amount of high spatial frequencies, and a luminance threshold map. The threshold map stores information about the maximum non-perceivable luminance differences for each pixel. The radiometric compensation is carried out in two passes: In the first pass the intensity values are translated and scaled globally depending on the surface reflectance and the image content itself. The result is analyzed for clipping errors. These errors are then blurred with a Gaussian kernel. The applied sigma is inverse proportional to the amount of high spatial frequencies in the local image areas. In the final pass the image intensities are translated and scaled globally, but the luminance values are also adjusted locally depending on the defocused clipping errors. Time dependent adaptation factors are used for global and local transformations to avoid popping artifacts in animated and interactive content.

Grundhöfer, A. and Bimber, O.
Real-Time Adaptive Radiometric Compensation
Bauhaus-University Weimar, Technical Report #823, 2006
To appear in IEEE Transactions on Visualization and Computer Graphics (TVCG), vol. 14, no. 1, pp. 97-108, 2008, (submitted: August 2006, accepted: February 2007, electronic version published: March 2007)

Category:

Science & Technology

Tags:

• computer
• augmented
• reality
• electronics
• environment
• projection
• compensation
• radiometric