Adobe Photoshop CS4 - Manual (Page 529)

522 USING PHOTOSHOP CS4
Web graphics
Last updated 1/10/2010
Examples of transparency and matting
A. Original image B. Transparency selected with a matte color C. Transparency selected with no matting D. Transparency deselected with a
matte color
Transparency Dithering When the Transparency option is selected, you can choose a method for dithering partially
transparent pixels:
• No Transparency Dither applies no dither to partially transparent pixels in the image.
• Diffusion Transparency Dither applies a random pattern that is usually less noticeable than Pattern dither. The
dither effects are diffused across adjacent pixels. If you select this algorithm, specify a Dither percentage to control
the amount of dithering that is applied to the image.
• Pattern Transparency Dither applies a halftone-like square pattern to partially transparent pixels.
• Noise Transparency Dither applies a random pattern similar to the Diffusion algorithm, but without diffusing the
pattern across adjacent pixels. No seams appear with the Noise algorithm.
Example of Pattern Transparency dithering (left) and applied to a web page background (right)
Interlace Displays a low-resolution version of the image in a browser while the full image file is downloading.
Interlacing can make downloading time seem shorter and can assure viewers that downloading is in progress.
However, interlacing also increases file size.
A B
C D