Adobe Photoshop CC 2014 v.14.xx - Manual (Page 213)

Exact
System (Mac OS)
System (Windows)
Web
Uniform
Local (Perceptual)
Local (Selective)
Local (Adaptive)
Master (Perceptual)
Master (Selective)
Master (Adaptive)
Custom
Previous
Number Of Colors
Color Inclusion And Transparency
Forced
options, you can choose using a local palette based on the current image’s colors. These are the available palette types:
Creates a palette using the exact colors appearing in the RGB image—an option available only if the image uses 256 or fewer
colors. Because the image’s palette contains all colors in the image, there is no dithering.
Uses the Mac OS default 8-bit palette, which is based on a uniform sampling of RGB colors.
Uses the Windows system’s default 8-bit palette, which is based on a uniform sampling of RGB colors.
Uses the 216-color palette that web browsers, regardless of platform, use to display images on a monitor limited to 256 colors. This
palette is a subset of the Mac OS 8-bit palette. Use this option to avoid browser dither when viewing images on a monitor display limited to
256 colors.
Creates a palette by uniformly sampling colors from the RGB color cube. For example, if Photoshop takes six evenly-spaced
color levels each of red, green, and blue, the combination produces a uniform palette of 216 colors (6 cubed = 6 x 6 x 6 = 216). The total
number of colors displayed in an image corresponds to the nearest perfect cube (8, 27, 64, 125, or 216) that is less than the value in the
Colors text box.
Creates a custom palette by giving priority to colors for which the human eye has greater sensitivity.
Creates a color table similar to the Perceptual color table, but favoring broad areas of color and the preservation of web
colors. This option usually produces images with the greatest color integrity.
Creates a palette by sampling the colors from the spectrum appearing most commonly in the image. For example, an
RGB image with only the colors green and blue produces a palette made primarily of greens and blues. Most images concentrate colors in
particular areas of the spectrum. To control a palette more precisely, first select a part of the image containing the colors you want to
emphasize. Photoshop weights the conversion toward these colors.
Creates a custom palette by giving priority to colors for which the human eye has greater sensitivity. Applies when
you have multiple documents open; takes all open documents into account.
Creates a color table similar to the Perceptual color table, but favoring broad areas of color and the preservation of
web colors. This option usually produces images with the greatest color integrity. Applies when you have multiple documents open; takes
all open documents into account.
Creates a palette by sampling the colors from the spectrum appearing most commonly in the image. For example, an
RGB image with only the colors green and blue produces a palette made primarily of greens and blues. Most images concentrate colors in
particular areas of the spectrum. To control a palette more precisely, first select a part of the image containing the colors you want to
emphasize. Photoshop weights the conversion toward these colors. Applies when you have multiple documents open; takes all open
documents into account.
Creates a custom palette using the Color Table dialog box. Either edit the color table and save it for later use or click Load to
load a previously created color table. This option also displays the current Adaptive palette, which is useful for previewing the colors most
often used in the image.
Uses the custom palette from the previous conversion, making it easy to convert several images with the same custom palette.
For the Uniform, Perceptual, Selective, or Adaptive palette, you can specify the exact number of colors to be displayed (up to
256) by entering a value for Colors. The Colors text box controls only how the indexed color table is created. Adobe Photoshop still treats the
image as an 8-bit, 256-color image.
To specify colors to be included in the indexed color table or to specify transparency in the image, choose
from the following options:
Provides options to force the inclusion of certain colors in the color table. Black And White adds a pure black and a pure white to
206