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DVANCED IMAGE PROCESSING
Hue, saturation, and lightness palette
This palette adjusts the image in reference to the HSB color model. These controls can be used to
manipulate the color image rather than producing a realistic representation.
The HSB color model defines color based upon human perception rather than photographic process-
es. Hue refers to each separate color in the model. Saturation is how vivid each colors is. Lightness
describes how bright or dark a color is in the color space.
The hue control is not a color balancing tool. It is a creative tool. When changing hue in the palette,
each colour is assigned a new hue depending on the degree of rotation through the color space. For
example, a very simple color space could have three colors: red, green, and blue. I have a red barn
next to a green tree with a blue sky. Now I rotate the image in the color space; the colors are reas-
signed a new hue based on the position – the barn is green, the tree is blue, and the sky is red. The
HSB color space is similar, but with many more hues; see the color example on the following page.
Unlike the brightness control in the brightness, contrast, color balance palette, the lightness control
does not change the apparent density of the colors equally. For example, with an extreme increase in
lightness, blue will not appear as light as yellow.
Original color space
New color space
Auto-setting button
Clicking the auto-setting button adjusts the saturation automatically without affecting the hue or light-
ness.
• Click the reset button to cancel any changes.
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Click the hue, saturation, and lightness button to
open the palette.
Drag the hue, saturation, or lightness slider, or enter
specific values in the corresponding text box to make
corrections.
• Dragging each slider to the right or inputting a
positive number in the text box increases the
saturation, and lightness. The hue slider rotates the
colors in the image through the color space; the
maximum position to the right (180°) is the same as
the maximum position to the left (–180°).
• Two color spaces are displayed at the bottom of the
palette. The top bar indicates the color space of the
original image. The bottom bar displays the relative
changes to the color space.
• Click the reset button to cancel any changes.
• Changes will be reflected in the displayed image.
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