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Histogram Test

Self administered test on histograms


Question 1.  In Figure 1 are two histograms labeled A and B.  Assume the two photographs that produced these histograms are of a general landscape scene.  After taking each photograph, the photographer stayed in the area and lounged around.  In which location, A or B, do you think the photographer would most likely wear sunglasses while relaxing outside?

  1. Answer
    1. 1B is the correct answer.  In histogram 1A, the pixels are clustered to the left.  Since the left part of a histogram represents dark tones, then it is likely that the photograph is of a dark or dimly lit landscape.  In histogram 1B, the pixels are clustered to the right.  Since the right part of a histogram represents light tones, then it is likely that the photograph is of a well lit or bright landscape.

Biased left histogram Figure 1A.

Biased right histogram Figure 1B.

Question 2.  In Figure 2 are two histograms labeled A and B.  One is of a color RGB image.  The other is of a black and white RGB image.  State which histogram is of which image.

  1. Answer
    1. Histogram A is of the black and white RGB image.  When an RGB image is converted to black and white, each pixel's individual channel values are recalculated to be the same.  This is how the color is removed from an image.  When the individual channel values are different, as in 2B, we have color.

All channels same Figure 2A.

Channels different Figure 2B.