8.5

• The Trace Contour filter thinly outlines the transitions of major brightness areas for each
color channel, producing a black-and-white outline of the picture. You have the option
to invert the results as well.
• The Add Noise filter applies random pixels to a picture to simulate pictures shot using
high-speed film. The filter applies an even pattern to shadow tones and midtones while
adding a smoother, more saturated pattern to the picture's lighter areas.
• The Median filter reduces or eliminates the look of motion on a specified region of a
picture. The effect searches pixels of similar brightness, and replaces the central pixel with
the median brightness value of the searched pixels; pixels that differ significantly from
adjacent pixels remain unaffected.
Picture Effects: Adjustments
Adjustments analyze pixels throughout a picture and map them to different values. If
you're familiar with an adjustment or effect from another application, you'll be comfortable
with adjustment controls in QuarkXPress as well.
• If an image is too light or too dark, you can use the Levels effect to brighten highlights,
compress shadows, and adjust midtones individually.
• To lighten or darken a picture, you can make precision tonal adjustments using the Curves
effect. Instead of limiting adjustments to shadows, highlights, and midtones, you can
adjust any point along a scale of 0% to 100% (for CMYK and grayscale) or 0 to 255 (for
RGB). The precise nature of this tool requires more experience and knowledge than using
the Levels effect.
• To make simple changes to the tonal range of a picture, you can use the
Brightness/Contrast effect to adjust the tonality of every pixel instead of individual
channels.
• Use the Color Balance effect to remove unwanted color casts or correct oversaturated or
undersaturated colors. This effect changes the overall mixture of colors in a picture for
generalized color correction.
• The Hue/Saturation effect is designed to adjust the overall color intensity and light in a
washed-out or muted picture, but is generally used as a special effect. The picture's current
hue (color cast), saturation (intensity), and lightness (degree of white light) are expressed
as zeros by default.
• To mimic an old printer's method for correcting specific colors, you can use the Selective
Color effect. This increases or decreases the amount of process color in each of the primary
colors in a picture. For example, if an apple is too purple, you can take cyan out of the
areas that affect red.
• For pictures intended for on-screen display (in Web layouts), you can adjust the white
point using the Gamma Correction effect. Adjusting the white point controls the brightness
of the picture's display on screen. To use the Gamma Correction dialog box, adjust the
midtones by entering a new value in the Gamma field or by dragging the slider. A higher
value produces a darker picture, overall.
174 | A GUIDE TO QUARKXPRESS 8.5: PLUS EDITION
PICTURES