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SUMMARY:Find and Replace Color Gradients - Mark Grundland
DTSTART:20050512T131500Z
DTEND:20050512T141500Z
UID:TALK4432@talks.cam.ac.uk
CONTACT:Alan Blackwell
DESCRIPTION:In this talk\, I propose a simple interactive technique for ad
 justing the global color balance of an image by finding and replacing colo
 r gradients. The aim is to make it easier to control interactive color cor
 rection\, a common user task in digital photography and video processing. 
 For instance\, the technique can assist in compensating for scene illumina
 tion\, selectively emphasizing scene details\, and applying a color scheme
  to impart a particular mood or theme. It may also prove useful in calibra
 ting the mapping between the disparate color gamuts of different capture a
 nd display devices. In information visualization\, color adjustment plays 
 an important role in post-processing\, where color distinctions are used t
 o direct the viewers attention to the relevant structure of the data. The 
 technique enables the user to improve the color composition of an image by
  choosing a harmonious combination of colors and adjusting their contrasts
  to highlight the key elements of the picture. \n\nThe user designates a s
 et of source color gradients and a matching set of target color gradients 
 to guide the algorithm in performing a continuous transformation of the im
 age colors. Compared with previous work\, this approach benefits from oper
 ating on color spans rather than individual colors. While a mapping betwee
 n colors suffices only to define a translation in color space\, a mapping 
 between color gradients defines a more general affine transformation. The 
 method works by applying a feature-based warping technique to calculate a 
 nonlinear volumetric deformation of the color space. In effect\, the resul
 ting image can be seen as a composite of the original image and its color 
 gradient transformations\, with the mask of each layer determined by the r
 egion of influence of its color gradient. \n\nThe results of this techniqu
 e will be discussed with a view towards the aesthetic considerations of co
 lor and contrast in graphic design. I will also briefly introduce other wo
 rk in interactive image enhancement developed at the Computer Laboratory o
 f the University of Cambridge\, including contrast brushes for local contr
 ast enhancement and histogram warping for global contrast enhancement.
LOCATION:Rainbow Room\, Computer Laboratory
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