Value (also referred to as luminance or tone) is independent of hue and refers to the relative light or dark character of the color. If you change a color image to black and white, you remove its hue but retain its tonal qualities. When you adjust the tint, you are adding more white to the hue, thereby making it a lighter value. When you adjust the shade, you are adding more black to the hue, making it a darker value.
