Adjusting hue and saturation

Saturation is the purity or vividness of a color, expressed as the absence of white. A color with 100% saturation contains no white. A color with 0% saturation corresponds to a shade of gray. A hue is the property that defines a particular color. For example, blue, green, and red are all hues.

Hue refers to the actual color (such as red or yellow). Saturation is the vividness of the color. Imagine bright orange, which is a highly saturated color. As the saturation is reduced (keeping the hue and lightness unchanged), the orange color becomes brownish, then taupe, and finally a middle neutral gray (after the saturation has been reduced to zero). Reducing the saturation drains the color away, leaving just the grayscale component. Taupe and mauve are low-saturation colors because they are quite neutral, with just a touch of color. Apple red and banana yellow are high-saturation colors. Saturation is a measure of how different a color is from a neutral gray of the same brightness.

In digital images, increasing the saturation can give the image brilliant color and “punch,” but too much saturation distorts colors and causes problems such as unnatural-looking skin tones. You can use the Vibrancy control to target only those areas that are low on saturation without affecting the rest of the image. For example, you can boost color in less saturated parts of an image without significantly altering skin tone.

Corel PaintShop Pro gives you four ways to alter the hue and saturation of a selection or of an entire image:

• You can replace all colors with a single color and saturation while leaving the lightness values unchanged. You can create sepia tones, like the brownish tones seen in old photographs, and other single-color effects.

• You can shift all colors and change their strength and lightness. Changing the hue shifts all pixels in an image to a different point on the color wheel. For example, if you change the red pixels to green, the green pixels turn to blue, and the yellow pixels turn to cyan. Adjusting the saturation changes the amount of gray in a color. (The level of gray increases as the saturation decreases.) Adjusting the lightness changes color brightness.

• You can replace one or more colors. For example, you can shift all greens to blues. You can also change the saturation or the lightness. When you adjust these values, all colors (both original and shifted colors) are adjusted.

• You can adjust only the least saturated colors in the image using the Vibrancy control and thus leave unaltered those pixels that are already relatively saturated. The result is that you will get a general improvement in the saturation in the colors of an image but not to the extent where colors become unrealistically bright. The Vibrancy control is recommended for adding saturation to portraits as it offers some protection for skin tones and is less likely to oversaturate and destroy the subject’s skin color.

Note: To create a duotone with more subtle color changes, do the following before choosing the Colorize command: Choose Image  Greyscale, and then choose Image  Increase Color Depth  RGB - 8 bits/channel.

• The Hue/Saturation/Lightness dialog box appears. The outer color ring in the dialog box represents the original values of colors in the image. The adjusted values will appear on the inner color ring.

If you choose to edit a color range, you can use the control ring that appears between the inner and outer color rings to modify the range to be edited. To change the range width, drag the two outer points on the control ring. To change the area in which the adjustment builds to full effect, drag the two inner bars (the full effect will be applied between the bars). To move the adjustment area, drag the white circles.

The Hue value represents the change from the original pixel color as the number of degrees of rotation around the 360-degree color wheel. A positive value indicates a clockwise rotation, and a negative value indicates a counterclockwise rotation. For example, when the Hue value is 180, blue becomes yellow, and green becomes magenta.

Dragging the slider up increases the saturation; dragging it down decreases the saturation. Values range from –100 to 100. A value of 0 preserves the original setting.

Dragging the slider up increases the lightness; dragging it down decreases the lightness. Values range from –100 to 100. A value of 0 preserves the original setting.

You can turn an image into a duotone (two-color) image by marking the Colorize check box, which converts the image to grayscale. To colorize the image, you can select a hue and adjust the saturation and lightness values.

Note: In the Hue Shift group box, the top row of color boxes shows 10 original colors, and the bottom row of color boxes shows the shifted colors. Each color is represented as degrees of rotation around the 360-degree color wheel.

You can also
Change the saturation of all colors	Type or set a value from –100 to 100 in the Saturation shift control.
Change the lightness of all colors	Type or set a value from –100 to 100 in the Lightness shift control.
Reset the colors to their default settings	In the Load Preset drop-list, choose Default.

Dragging the slider to the right increases the saturation of the least saturated colors while leaving highly saturated colors unaltered; dragging it to the left decreases the saturation.