Humans are extremely sensitive to color fidelity. Look closely as those processed images.
You can tell that something is "off" about them, because while the algorithm is extremely good, it can't reproduce the true color gamut of reality, or even of a low quality jpeg that is based on a real photograph.
Humans are naturally sensitive to color, but not to hue fidelity, as hue synthesis shows: all hues are synthesized out of 3 basic wavelengths, color displays are based on this. Also, we tolerate B&W and sepia images well, we even love them. We are sensitive to hue saturation and contrast, and the discussed algorithm fulfills these two requirements. Furthermore, we have been desensitized by the heavy use of compression in color images and by uncalibrated displays.
You can tell that something is "off" about them, because while the algorithm is extremely good, it can't reproduce the true color gamut of reality, or even of a low quality jpeg that is based on a real photograph.