Photoshop Tutorials - Color Balance. Hue/Saturation
Hue/Saturation window lets you set the Hue, Saturation and Lightness for any color component of the image, based on the color scheme above. In the Edit dropdown menu you can choose between full color range (Master) and six color ranges of the additive (RGB) and subtractive (CMYK) models: Reds, Yellows, Greens, Cyans, Blues, and Magentas.
Hue option sets the needed hue with the slider or by entering the numerical value into the field (from -180 to +180 degrees in the color circle radius, where 0 is the current color).
Saturation option works similar to the Hue option, but its numerical value range is from -100 to +100.
Lightness is used to increase/decrease the brightness with the range from -100 to +100. It is rarely used as commands like Brightness/Contrast or Levels let you set up the brightness in a more precise and effective manner.
In the bottom part of the dialogue window, there are two spectrums. The top spectrum is the default image spectrum and the bottom spectrum is the spectrum of the image with the settings applied.
The Colorize checkbox allows you to do monochromatic rendering of the image. In other words, it transforms the image into a set of hues of the single color. When this box is checked, the Hue is set to the zero value from the color scheme (red color). Moving the Hue slider, you can choose any color (the color is displayed in the bottom spectrum line). The image will be drawn with gradations of selected color.
Such method is good for color rendering (coloring) the black-and-white photos (if they are scanned as grayscale and need to be converted to RGB).