The effect of exposure on MaxRGB color constancy
Funt, B. and Shi, L.,
"The Effect of Exposure on MaxRGB Color Constancy,"
Proc. SPIE Volume 7527 Human Vision and Electronic Imaging XV, San Jose, Jan. 2010.
Abstract:
The performance of the MaxRGB illumination-estimation method for color constancy and automatic
white balancing has been reported in the literature as being mediocre at best; however, MaxRGB
has usually been tested on images of only 8-bits per channel. The question arises as to whether
the method itself is inadequate, or rather whether it has simply been tested on data of
inadequate dynamic range. To address this question, a database of sets of exposure-bracketed
images was created. The image sets include exposures ranging from very underexposed to slightly
overexposed. The color of the scene illumination was determined by taking an extra image of the
scene containing 4 Gretag Macbeth mini Colorcheckers placed at an angle to one another. MaxRGB
was then run on the images of increasing exposure. The results clearly show that its performance
drops dramatically when the 14-bit exposure range of the Nikon D700 camera is exceeded, thereby
resulting in clipping of high values. For those images exposed such that no clipping occurs, the
median error in MaxRGB's estimate of the color of the scene illumination is found to be
relatively small.
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