Peceptual rendering of HDR in painting and photography

Pictures can be drawn by hand, or imaged by optical means. Over time, pictures have changed from being rare and unique to ubiquitous and common. They have changed from treasures to transients. This paper summarizes many picture technologies, and discusses their dynamic range, their color and tone-scale rendering and their spatial image processing. High Dynamic Range (HDR) image capture and display has long been an interest for artists and photographers. The discipline of reproducing scenes with a high range of luminances has a 5-century history that includes painting, photography, electronic imaging and image processing. HDR images render high-range scene information into lowrange reproductions. This paper studies the artistic techniques and scientific issues that control HDR image capture and reproduction. Both the artist and the scientist synthesize HDR reproductions with spatial image processing. The artists paints, or dodges and burns, the image he visualizes based on his human visual processing. The scientist, using algorithms that mimic vision, calculates perceptually correct renditions with inaccurate reproductions of scene radiances. The paper will discuss artists’ techniques used in both painting and photography for HDR compression. It will also describe how optical veiling glare severely limits the range of luminance that can be captured and seen. The improvement in quality in digital HDR reproductions, as in HDR in art, depends on the spatial rendering of details in the highlights and shadows.