Color Channel

hue(@color) Extracts the hue channel of a color object in the HSL color space.
saturation(@color) Extracts the saturation channel of a color object in the HSL color space.
lightness(@color) Extracts the lightness channel of a color object in the HSL color space.
hsvhue(@color) Extracts the hue channel of a color object in the HSV color space.
hsvsaturation(@color) Extracts the saturation channel of a color object in the HSV color space.
hsvvalue(@color) Extracts the value channel of a color object in the HSV color space.
red(@color) Extracts the red channel of a color object.
green(@color) Extracts the green channel of a color object.
blue(@color) Extracts the blue channel of a color object.
alpha(@color) Extracts the alpha channel of a color object.
luma(@color) Calculates the luma (perceptual brightness) of a color object.
luminance(@color) Calculates the value of the luma without gamma correction.
The functions above take in a color value.
@h: hue(hsl(90, 100%, 50%));
@s: hsvsaturation(rgb(100,100,200));
@l: 50%;

@c:hsl(@h,@s,@l);
.a { color: @c;
     width: luma(@c);
     height: luminance(@c);
}

.a {
  color: #80bf40;
  width: 42%;
  height: 66%;
}