Adobe photoshop elements User Manual

CHAPTER 11

Choose a color reduction algorithm for gener-

ating the color lookup table: 

Perceptual to create a custom color table by 

giving priority to colors for which the human eye 
has greater sensitivity. 

Selective to create a color table similar to the 

Perceptual color table, but favoring broad areas 
of color and the preservation of Web colors. 
This color table usually produces images with 
the greatest color integrity. Selective is the 
default option.

Adaptive to create a custom color table by 

sampling colors from the spectrum appearing 
most commonly in the image. For example, an 
image with only the colors green and blue 
produces a color table made primarily of greens 
and blues. Most images concentrate colors in 
particular areas of the spectrum. 

Web to use the standard 216-color color table 

common to the Windows and Mac OS 8-bit 
(256-color) palettes. This option ensures that no 
browser dither is applied to colors when the image 
is displayed using 8-bit color. (This palette is also 
called the Web-safe palette.) If your image has 
fewer colors than the total number specified in the 
color palette, unused colors are removed. Using 
the Web palette can create larger files, and is 
recommended only when avoiding browser dither 
is a high priority. (See “Previewing and controlling 
dithering” on page 235.) 

Custom to preserve the current color table as a 

fixed palette that does not update with changes to 
the image.

To specify the maximum number of colors in 

the color palette, select a number from the Colors 
pop-up menu, enter a value in the text box, or use 
the arrows to change the number of colors. If the 
image contains fewer colors than the number 
specified, the color table will contain only the 
number of colors in the image. 

You can choose the Auto option when working 
with a fixed color palette. This option determines 
the number of colors in the color table based on 
the frequency of colors in the image. Choose Auto 
if you want Photoshop Elements to determine the 
optimal number of colors in the color table.

Choose a dithering algorithm option, and 

specify a percentage for Dither. (See “Previewing 
and controlling dithering” on page 235.)

If the image contains transparency, select 

Transparency to preserve transparent pixels as 
transparent; deselect Transparency to fill fully and 
partially transparent pixels with the Matte color. 
(See “Making transparent and matted images” on 
page 233.)

Select Interlaced to create an image that displays 

as low-resolution versions in a browser while the 
full image file is downloading. Interlacing can 
make downloading time seem shorter and assures 
viewers that downloading is in progress.