Colors -> Brightness and Contrast -> (Brightness: 0; Contrast: 20)
Colors -> Hue Saturation -> (Hue: -10; Lightness: 0; Saturation: 20)
Colors -> Curves -> Select Red Channel -> and make changes to curves. Similarly make changes to green and blue channels.
Colors -> Hue Saturation -> (Hue: -10; Saturation: -20)
