Problematic Images

Here are some examples of problematic images. All images were assumed to have a gamma of 2.2 and we de-gamma'd before histogramming.

The first column is the original image.

The second column is the histogram in log (r/b) and log (g/b) space.

All pixel values less than 10 were clipped to 10.
The coordinates (0,0) are at the center of the image, (+,+) at the lower right, and (-,-) at the upper left.
Pixels where r+g+b < 32 were not counted.
The vertical axis is red, the horizontal axis is green.
White is at 0,0. Pure red is at the lower left. Pure green is at the upper right. Pure blue is at the upper left. Yellow is at the lower right.

The third column is the histogram in r/(r+g+b) and g/(r+g+b) space.

Pixels where r+g+b < 32 were not counted.
The vertical axis is red, the horizontal axis is green.
The coordinates (0,0) are at the upper right.
White is 1/3 from the left and 1/3 from the top.
Values in the lower right triangle of the histogram represent infeasible colors.

Note that the histograms are displayed with a gamma of 3.0 to enhance the visibility of low occupancy bins.

Lena Image
Histogram
Histogram