Human hair color used in physical anthropology and medicine to determine the shades of hair color. The scale uses the following designations: A (very light blond), B to E (light blond), F to L (blond), M to O (dark blond), P to T (light brown to brown), U to Y (dark brown/black) and Roman numerals I to IV (red) and V to VI (red blond). Brown hair is characterized by higher levels of eumelanin and lower levels of pheomelanin. Of the two types of eumelanin (black and brown), brown-haired people have brown eumelanin; they also usually have medium-thick strands of hair. Brown-haired girls
Shades of gray but are close to each other, which is what makes it a shade of gray. The colors white and black are not usually thought of as shades of gray, but they can be thought of as shades of achromatic gray, as both contain equal amounts of red, blue and green. White is at the extreme upper end of the achromatic value scale and black is at the extreme lower end of the achromatic value scale, with all the colors normally considered tones of achromatic gray colors in between. Since achromatic colors have no hue, the hue code (h code) is