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To appear in the ACM SIGGRAPH conference proceedings Removing Photography Artifacts using Gradient Projection and
 

Summary: To appear in the ACM SIGGRAPH conference proceedings
Removing Photography Artifacts using Gradient Projection and
Flash-Exposure Sampling
Amit Agrawal Ramesh Raskar Shree K. Nayar Yuanzhen Li
Mitsubishi Electric Research Labs (MERL), Cambridge, MA Columbia University
Figure 1: Undesirable artifacts in photography can be reduced by comparing image gradients at corresponding locations in a pair of flash
and ambient images. (Left) Removing flash hot spot. Flash and ambient images of a museum scene, where the flash image reveals more of
the scene but includes a strong highlight. We combine gradients in flash and ambient images to produce an enhanced flash image with the
highlight removed. (Right) Removing self reflections. Flash and ambient images of a painting, where the ambient image includes annoying
reflections of the photographer. The low-exposure flash image avoids reflections, but has a hot spot. We remove the reflections in the ambient
image by removing the component of the ambient image gradients perpendicular to the flash image gradients. For visual verification, we
show the computed reflection layer.
Abstract
Flash images are known to suffer from several problems: saturation
of nearby objects, poor illumination of distant objects, reflections
of objects strongly lit by the flash and strong highlights due to the
reflection of flash itself by glossy surfaces. We propose to use a
flash and no-flash (ambient) image pair to produce better flash im-
ages. We present a novel gradient projection scheme based on a
gradient coherence model that allows removal of reflections and

  

Source: Agrawal, Amit - Mitsubishi Electric Research Labs
Majumder, Aditi - School of Information and Computer Science, University of California, Irvine

 

Collections: Computer Technologies and Information Sciences; Engineering