Your last images is a bit underexposed. Analysing this image shows that only 14556 different colors are used. A "real photo" (randomly picked from my collection) with a nacked person in front of a white background and scaled to the same imagesize shows more than 40000 different colors. The colorspace histogram of your image covers only 70% from the available bandwidth.
"Normalizing" HSV distribution gives a better, but not a perfect result, even if color-saturation is lowered.

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