Hue, Saturation, and Luminance Adjustments
The three sets of color adjustments in the HSL panel look a bit overwhelming at first glance, with all the different slider controls for hue, saturation, and luminance (see Figure 10). You'll feel more comfortable using these adjustments when you understand what hue, saturation, and luminance are.
Figure 10 The HSL sliders in this example were positioned to improve colors. Predominantly the blue sky was enhanced, and the red saturation was reduced along with the luminance.
Every color consists of three fundamental elements to describe its physical characteristics:
- Hue is identified by the name of the color, such as red, green, or blue. You can adjust the hue to a different color value by moving its adjustment slider to the left or right. For example, if you move the yellow slider to the right under the Hue adjustment, it becomes greener; move it to the left for more orange. Hue represents a shift in the color.
- Saturation can be described as the intensity of color. Other words used to describe saturation include heat or vividness. Saturation adjustments should be handled with care. Too much color saturation can produce cartoon-like results that might look great onscreen, but will be difficult to reproduce in the print process. My advice is to stay within the colors of nature and not adjust the saturation level to an extreme. When saturation adjustments become extreme, the image information starts to degrade as well. By developing an approach that bumps the saturation intensity levels in small increments, you can create visually pleasing image-rendering results. Desaturating an image color is the process of introducing gray to the color. When an image is completely desaturated, it lacks color and is therefore just a grayscale rendering.
- Luminance is the brightness or darkness of the color. Using the luminance adjustment on specific colors makes that color lighter or darker.
Experiment with the HSL control sliders to get comfortable with these image adjustments. They can be quite helpful at improving color intensity. Just remember not to go overboard with these adjustments, especially saturation.
The Color Adjustment panel is a separate but combined adjustment that contains all the hue, saturation and luminance adjustments for a specific color (see Figure 11). You can select a color such as red and have the adjustments for hue, saturation, and luminance together, rather than spread out separately in the panel. When you choose a specific color, all three elements of that color are presented together for adjustment.
Figure 11 Color adjustment is a combination of the hue, saturation, and luminance for a specific color selected—in this case, the color red.
The Grayscale Mix (see Figure 12) is a wonderful adjustment tool that can control the color content of the image to create grayscale values. Clicking the Grayscale header renders your image in black-and-white. Start moving the control sliders for each color to produce the desired black and white values within the image.
Figure 12 The Grayscale Mix uses color information to adjust the gray values within the image.
Selecting the Before and After view option in the Develop toolbar lets you monitor the color and black-and-white images side by side (see Figure 13). This helps target a specific color and lets you easily compare how your adjustments affect the grayscale values produced. Each color slider control actually indicates how light or dark a color appears in the black-and-white rendering of the image.
Figure 13 Green walls, red chairs, and orange trim can be rendered in a variety of ways in black-and-white.