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PhotoTechEDU Day 32 - Art, Science and Reality of High Dynamic Range (HDR) Im...

Google Tech TalksJanuary, 25 2008ABSTRACTHigh Dynamic Range (HDR) image capture and display has become animportant engineering topic. The discipline of reproducing scenes witha high range of luminances has a five-century history that includespainting, photography, electronic imaging and image processing. HDRimages are superior to conventional images. There are two fundamentalscientific issues that control HDR image capture and reproduction. Thefirst is the range of information that can be measured using differenttechniques. The second is the range of image information that can beutilized by humans. Optical veiling glare severely limits the range ofluminance that can be captured and seen.In recent experiments, we measured camera and human responses tocalibrated HDR test targets. We calibrated a 4.3-log-unit test target,with minimal and maximal glare from a changeable surround. Glare is anuncontrolled spread of an image-dependent fraction of scene luminancein cameras and in the eye. We use this standard test target to measurethe range of luminances that can be captured on a camera's imageplane. Further, we measure the appearance of these test luminancepatches. It is the improved quantization of digital data and thepreservation of the scene's spatial information that cause theimprovement in quality in HDR reproductions. HDR is better thanconventional imaging, despite the fact the multiple- exposure-HDRreproduction of luminance is inaccurate. This talk describes thehistory of HDR image processing techniques including painting,photography, and electronic image processing (analog and digital) overthe past 40 years. It reviews the development of Retinex theory, andother spatial-image- processing algorithms, that calculate appearancein images from arrays of radiances.Speaker: John McCannJohn McCann received a B.A. degree in Biology from Harvard Universityin 1964. He worked in, and later managed, the Vision ResearchLaboratory at Polaroid from 1961 to 1996. He has studied human colorvision, digital image processing, large format instant photography andthe reproduction of fine art. He is a Fellow of IS&T. He is a pastPresident of IS&T and the Artists Foundation, Boston. He is currentlyconsulting and continuing his research on color vision. He is theIS&T/OSA 2002 Edwin H. Land Medalist and IS&T 2005 Honorary Member andwill be a 2008 Fellow of the Optical Society of America.
Length: 01:05:11


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