Using the Variations command

The Variations command lets you adjust the color balance, contrast, and saturation of an image by showing you thumbnails of alternatives.

This command is most useful for average-key images that don’t require precise color adjustments. It does not work on indexed-color images (Photoshop).

To use the Variations command:

1 Open the Variations dialog box. (See “Making color adjustments” on page 132.)

Note: If the Variations command does not appear in the Adjustments submenu, the Variations plug-in module may not have been installed. (See “Using plug-in modules” on

page 58.)

The two thumbnails at the top of the dialog box show the original selection (Original) and the selection with its currently selected adjustments (Current Pick). When you first open the dialog box, these two images are the same. As you make adjustments, the Current Pick image changes to reflect your choices.

2 Select Show Clipping if you want to display a neon preview of areas in the image that will be clipped by the adjustment—that is, converted to pure white or pure black. Clipping can result in undesirable color shifts, as distinct colors in the original image are mapped to the same color. Clipping does not occur when you adjust midtones.

Note: Clipped colors are not the same as out-of-gamut colors.

3 Select what to adjust in the image:

•Shadows, Midtones, or Highlights to indicate whether you want to adjust the dark, middle, or light areas.

•Saturation to change the degree of hue in the image. If you exceed the maximum saturation for a color, it may be clipped.

4Drag the Fine/Coarse slider to determine the amount of each adjustment. Moving the slider one tick mark doubles the adjustment amount.

5Adjust the color and brightness:

•To add a color to the image, click the appropriate color thumbnail.

•To subtract a color, click the thumbnail for its opposite color. (See “About the color wheel” on page 146.) For example, to subtract cyan, click the More Red thumbnail.

•To adjust brightness, click a thumbnail on the right side of the dialog box.

Each time you click a thumbnail, other thumbnails change. The center thumbnail always reflects the current choices.

Applying special color effects to images

The Desaturate, Invert, Equalize (Photoshop), Threshold (Photoshop), and Posterize (Photoshop) commands change colors or brightness values in an image but are typically used for enhancing color and producing special effects, rather than for correcting color.

Note: You can also make color adjustments by blending colors from different channels. (See “Mixing color channels (Photoshop)” on page 271.)

Using the Desaturate command

The Desaturate command converts a color image to a grayscale image in the same color mode. For example, it assigns equal red, green, and blue values to each pixel in an RGB image to make it appear grayscale. The lightness value of each pixel does not change.

This command has the same effect as setting Saturation to –100 in the Hue/Saturation dialog box.

Note: If you are working with a multilayer image, Desaturate converts the selected layer only.

To use the Desaturate command:

Choose Image > Adjustments > Desaturate.

Using the Invert command

The Invert command inverts the colors in an image.You might use this command to make a positive black-and-white image negative or to make a positive from a scanned black- and-white negative.

Note: Because color print film contains an orange mask in its base, the Invert command cannot make accurate positive images from scanned color negatives. Be sure to use the proper settings for color negatives when scanning film on slide scanners.

When you invert an image, the brightness value of each pixel in the channels is converted to the inverse value on the 256-step color-values scale. For example, a pixel in a positive image with a value of 255 is changed to 0, and a pixel with a value of 5 to 250.

To use the Invert command:

Choose Image > Adjustments > Invert, or choose Layer > New Adjustment Layer > Invert (Photoshop).

Using the Equalize command (Photoshop)

The Equalize command redistributes the brightness values of the pixels in an image so that they more evenly represent the entire range of brightness levels.When you apply this command, Photoshop finds the brightest and darkest values in the composite image and remaps them so that the brightest value represents white and the darkest value represents black. Photoshop then attempts to equalize the brightness—that is, to distribute the intermediate pixel values evenly throughout the grayscale.

You might use the Equalize command when a scanned image appears darker than the original and you want to balance the values to produce a lighter image. Using Equalize together with the Histogram command lets you see before-and-after brightness comparisons.

To use the Equalize command:

1Choose Image > Adjustments > Equalize.

2If you selected an area of the image, select what to equalize in the dialog box, and click OK:

•Equalize Selected Area Only to evenly distribute only the selection’s pixels.

•Equalize Entire Image Based on Selected Area to evenly distribute all image pixels based on those in the selection.

Using the Threshold command (Photoshop)

The Threshold command converts grayscale or color images to high-contrast, black-and- white images. You can specify a certain level as a threshold. All pixels lighter than the threshold are converted to white; all pixels darker are converted to black. The Threshold command is useful for determining the lightest and darkest areas of an image.

To use the Threshold command to convert images to black and white:

1 Open the Threshold dialog box. (See “Making color adjustments” on page 132.)

The Threshold dialog box displays a histogram of the luminance levels of the pixels in the current selection.

2 Drag the slider below the histogram until the threshold level you want appears at the top of the dialog box, and click OK. As you drag, the image changes to reflect the new threshold setting.

To use the Threshold command to identify representative highlights and shadows:

1Open the Threshold dialog box. (See “Making color adjustments” on page 132.)

2Select Preview.

3To identify a representative highlight, drag the slider to the far right until the image becomes pure black. Drag the slider slowly toward the center until some solid white areas appear in the image, and place a color sampler on one of the areas.

4To identify a representative shadow, drag the slider to the far left until the image becomes pure white. Drag the slider slowly toward the center until some solid black areas appear in the image, and place a color sampler on one of the areas.

5Click Cancel to close the Threshold dialog box without applying changes to the image.

You can use the Info palette readouts of the two color samplers to determine your highlight and shadow values.

Using the Posterize command (Photoshop)

The Posterize command lets you specify the number of tonal levels (or brightness values) for each channel in an image and then maps pixels to the closest matching level. For example, choosing two tonal levels in an RGB image gives six colors, two for red, two for green, and two for blue.

This command is useful for creating special effects, such as large, flat areas in a photograph. Its effects are most evident when you reduce the number of gray levels in a grayscale image. But it also produces interesting effects in color images.

If you want a specific number of colors in your image, convert the image to grayscale and specify the number of levels you want. Then convert the image back to the

previous color mode, and replace the various gray tones with the colors you want.

To use the Posterize command:

1Open the Posterize dialog box. (See “Making color adjustments” on page 132.)

2Enter the number of tonal levels you want, and click OK.