Adobe PHOTOSHOP ELEMENTS 2 User Manual page 225

• Browser dither occurs when a Web browser
using an 8-bit color display (256-color mode)
attempts to simulate colors that aren't in the 8-
bit color palette. Browser dither can occur with
GIF, PNG, or JPEG images. In Photoshop
Elements, you can control the amount of
browser dither by shifting selected colors in the
image to Web-safe colors. You can also specify
Web-safe colors when choosing a color in the
Adobe Color Picker.
Previewing and controlling application
dither
You can preview application dither in GIF and
PNG-8 images. The Dither Algorithm pop-up
menu lets you choose a dithering method for the
image. Images with primarily solid colors may
work well without dithering. Conversely, images
with continuous-tone color (especially color
gradients) may require dithering to prevent color
banding.
GIF image without dithering produces banding, GIF image
with Diffusion dither set to 100% dither simulates continuous
tones
ADOBE PHOTOSHOP ELEMENTS 2.0
To control application dither:
Choose an option from the Dither Algorithm
1
pop-up menu:
No Dither to apply no application dither to
•
the image.
Diffusion to apply a random pattern that is
•
usually less noticeable than Pattern dither. The
dither effects are diffused across adjacent pixels.
Pattern to apply a halftone-like square pattern
•
to simulate any colors not in the color table.
Noise to apply a random pattern similar to the
•
Diffusion dither method, but without diffusing
the pattern across adjacent pixels. Unlike the
Diffusion method, no seams appear with the
Noise dither method.
If you chose Diffusion as the dithering algorithm,
drag the Dither slider, or enter a value to select a
dithering percentage.
The Dither percentage controls the amount of
dithering that is applied to the image. A higher
dithering percentage creates the appearance of
more colors and more detail in an image, but can
also increase the file size. For optimal compression
and display quality, use the lowest percentage of
application dither that provides the color detail
you require.
Previewing browser dither
You can preview browser dither directly in
Photoshop Elements or in a browser that uses an
8-bit color display (256-color mode).
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User Guide