Conversion of the image to mode Indexed Color

1. Be convinced that the image is in mode RGB.
   
2. Execute commands Image> Mode> Indexed Color (the Image> the Mode> Indexed color) and click by the button APPRX.
   
   • At desire install flag Preview (Print preview), then select one of following points in the field Palette (Palette) - fig. 23.2 see:
     
   • Exact (Exact) if the image contains 256 or less colors. Thus any color will not be remote;
     
   • System (Mac OS) (System (Mac OS)) if be going to export a file to application which perceives only a palette May OS, installed by default;
     
   • System (Windows) (System (Windows)) if be going to export the image to applications on platform Windows;
     

Fig. 23.2. Pop up menu Palette

• Web (Network) if intend to load a file in a network. This option restricts image color set to that set which is accessible in the majority of web browsers;
  
• Uniform (Uniform) to create the color lookup table, uniformly arranged on a spectrum. Thus prevailing colors of the image are not considered;
  
• Local (Local) (Perceptual (Considering perception), Selective (Selective) or Adaptive (Adaptive)), чтобычюздать the color lookup table on a basis only those colors which are included into the image;
  
• Master (Special) uses the special color lookup table created in advance on the basis of group of images.
  

  Select variant Perceptual, Selective or Adaptive depending on what colors are desirable for saving at conversion of the image to mode Indexed Color. More in detail Optimization of images is told about these three palettes for a network in program ImageReady »this chapter in section«;
  

• Custom (For choice the user) to create own palette. At desire edit the color lookup table and click by the button APPRX. (Click by button Save (to Save) if you want and to use the color lookup table further. Click by button Load (to Load) allows to load earlier saved table.) click by button OK and pass following steps;
  
• Previous (Previous) to use a palette applied in the previous conversion if it was fulfilled.
  

4. If one of options Local or Master (Perceptual, Selective or Adaptive) has been activated or variant Uniform it is necessary to enter an amount of colors in the table (fig. 23.3) is selected. The less than colors in the image, the it is less file size, but the quality of a picture is worse.
   
5. Select one of following points of pop up menu Forced (Forcedly) to add certain colors in the table:
   
   • Black and White (Black and white) adds purely black and purely white colors;
     
   • Primaries (Basic colors) adds red, green, dark blue, cyanic, fuchsin, yellow, black and white;
     
   • Web adds 216 Web-colors (remaining colors correspond to palette Selective);
     
   • Custom (For choice the user) adds the colors defined by the user.
     
6. Install flag Transparency (About-. зрачность) to save the transparent areas of the image. Or remove this flag, in that case the transparent areas will be flooded by the color set in the field Matte (Border), or white if point None is selected from this field (is not present).
   

If the image contains the transparent areas, select suitable color in the field Matte (Border) to fill partially transparent areas on image edge.

Fig. 23.3. Input of an amount of colors in the field Colors

Drawing in mode Indexed Color

In mode Indexed Color by means of tools Pencil (Pencil) and Brush (Paintbrush) it is possible to put only completely opaque dabs. For these tools leave slider Opacity (Opacity) on a mark of 100 %. The unique mode of mixing at which it is possible to reduce opacity, is Dissolve to (Dissolve).

Option Forced

If it is necessary to check, what colors will be selected for a color box besides what are offered by option Forced (Forcedly), select area (or some areas), containing those colors, which should be placed on a palette before to translate the image in mode Indexed Color, and then in the field Palette on a step 3 select one of points Local (Perceptual), Local (Selective) or Local (Adaptive).

Also it is possible to use option Master to supervise colors of the image (more in detail about it Creation of a special palette in program ImageReady for images in mode Indexed Color »the present chapter is written in section«).

7. Select one of menu items Dither (Blur): None (is not present), Diffusion (Diffusion), Pattern (Pattern) or Noise (Noise) to imitate additional shades which are not present in the color lookup table. If variant None images with color sharp transitions will look, as posters so use this option only in a case when such sharp transitions of color are not present is selected. Option Diffusion (Diffusion) leads to changeover of color by the nearest shade, but can sometimes make noticeable separate points. Variant Pattern imitates missing shades, using repeating pattern. Option Noise creates almost inaudible effect of appearance of separate points in that place where there transits boundary between colors.
   
8. If in menu Dither (Blur) point Diffusion has been selected, it is possible to enter value in the field Amount (Amount) to regulate percent of colors which will be affected by the given operation. Selecting this option, install flag Preserve Exact Colors (to Save exact colors), thus blur will not be applied to those areas where color of the image completely correspond to any color from a palette. Do not try to view beforehand the gained effect as, most likely, you do not see any difference.
   
9. Click by the button APPRX.