here are some official SNK sprites, they still have amazing internal artists.  A lot of these were first shown as the achivement sprites for he console version of the game but with the release of KOFI2012 they have shown the sprites as cards. The new sprites are Oswald, Geese, Shroom, Rimelo, Shion, Magaki, Heidern, Orochi, Adel, Rose, Botan, Mukai, Shingo, Momoko, Igniz, and Whip.

The Magic Number is Seven:

One of the first things that caught my eye regarding these sprites is that there seems to be one specific rule that gets enforced a lot. This rule is that if there is a prominent color used for a character, there are going to be seven tones to it with rare exception.This applies to skin, hair, and clothing alike regardless of the material.

I've picked out 3 random samples from the sprites at my disposal to help illustrate things a bit better. The first image covers Terry's denim jeans, the next has Joe's skin tone, and the last has Mai's hair. Despite being fairly different subjects, each have the same number of tones, and they each behave in the same way. Here's the breakdown from lightest to darkest:

    Tones 1 and 2 will act as the primary highlights. Although the amount of tone 1 used will depend on the nature of the surface, tone 2 will be used as an outline for it that is consistently 1-2 pixels wide.
    Tone 3 will be the flat tone used for non highlighted areas that still receive light source. There is no predetermined width for this section, just what visually makes sense.
    Tones 4 and 5 are the transition colors between the lit portion of the sprite and the part in shadow. In the examples here, the colors used for these 2 tones tend to lean towards become warmer tones which come off as reddish purple variants of the lit colors before it. While the width depends on the nature of the curves involved, the two will have some level of anti-aliasing done when the change from light to dark is a sharp one. Joe's skin serves as a good example of that.
    Tone 6 is the primary dark tone that is used in shadowed areas. Basically, if the area is obscured somehow, this will be the color you would be seeing.
    Tone 7 is the outline color for the dark areas. Although Joe's chest and Terry's jeans show it fairly clearly in action, it still is present within Mai's hair tones although the change is very subtle in her default colors.