Adobe 29180155 User Guide - Page 154

ADOBE PHOTOSHOP ELEMENTS 4.0 149 User Guide Dither Specifies whether to use a dither pattern or not. Unless you're using the Exact color table option, the color table may not contain all the colors used in the image. To simulate colors not in the color table, you can dither the colors. Dithering mixes the pixels of the available colors to simulate the missing colors. • None Does not dither colors but instead uses the color closest to the missing color. This tends to result in sharp transitions between shades of color in the image, creating a posterized effect. • Diffusion Uses an error-diffusion method that produces a less structured dither than the Pattern option. To protect colors in the image that contain entries in the color table from being dithered, select Preserve Exact Colors. This is useful for preserving fine lines and text for web images. • Pattern Uses a halftone-like square pattern to simulate any colors not in the color table. • Noise Helps to reduce seam patterns along the edges of image slices. Amount Specifies the percentage of image colors to dither. A higher amount dithers more colors, but may increase file size. Preserve Exact Colors Prevents colors in the image that are in the color table from being dithered. To edit colors in an indexed-color table You can edit colors in the color table to produce special effects, or assign transparency in the image to a single color in the table. 1 Open the indexed-color image in the Editor. 2 Choose Image > Mode > Color Table. 3 Click or drag in the table to choose the color or range of colors you want to change. 4 Choose a color from the Color Picker or sample a color from the image. If you are changing a range of colors, Photoshop Elements creates a gradient in the color table between the starting and ending colors. The first color you choose in the Color Picker is the beginning color for the range. When you click OK, the Color Picker reappears, so that you can choose the last color in the range. The colors you selected in the Color Picker are placed in the range you selected in the Color Table dialog box. 5 Click Preview to view the results of the changes you have made to the image. 6 Click OK in the Color Table dialog box to apply the new colors to the indexed-color image. To assign transparency to a single color in an indexed-color table 1 In the Editor, choose Image > Mode > Color Table. 2 Select the eyedropper, and click the desired color in the table or in the image. The sampled color is replaced with transparency in the image. 3 Click OK to close the color table. To use a predefined indexed-color table 1 In the Editor, choose Image > Mode > Color Table. 2 Select an option from the Table menu: Black Body Displays a palette based on the different colors a black body radiator emits as it is heated-from black to red, orange, yellow, and white.