Changing bitmaps to the paletted color mode

The paletted color mode, also called indexed color mode, is sometimes used for images on the World Wide Web. When you convert an image to the paletted color mode, a fixed color value is assigned to each pixel. These values are stored in a compact color table, or palette containing up to 256 colors. As a result, the paletted color mode image contains less data than a 24 bit color mode image, and it has a smaller file size. Conversion to paletted color mode works best on images that have a limited range of colors.


Choosing, editing, and saving a color palette

When you change an image to the paletted color mode, you can use a predefined palette, or you can customize a color palette by replacing individual colors.


Saving conversion settings

After you choose a color palette and set the dithering and range sensitivity for changing an image to the paletted color mode, you can save the settings as a conversion preset that you can use with other images. You can add as many conversion presets as you want.

The color palette you use is called the processed color palette. It can be saved for use with other images.

For more information about the predefined color palettes available for the paletted color mode, see “Palette types.” For more information about creating and opening custom color palettes, see “Creating custom color palettes.”


Dithering

Changing images to the paletted color mode lets you use dithering to enhance color information. Dithering places pixels with specific colors or values relative to other pixels of a specific color. The relationship of one colored pixel to another creates the appearance of additional colors that do not exist in the color palette.

You can use two types of dithering: ordered dithering and error diffusion. Ordered dithering approximates color blends using fixed dot patterns; as a result, solid colors are emphasized and edges appear harder. Error diffusion scatters pixels irregularly, making edges and colors softer. Jarvis, Stucki, and Floyd-Steinberg are conversion options that provide error diffusion.

The Ordered dithering option applies more quickly than the error diffusion options (Jarvis, Stucki, and Floyd-Steinberg) but is less accurate.


Specifying a range-sensitivity color

You can change an image to the paletted color mode and specify a focus color and a range sensitivity for the focus color, so that the focus color and colors that fall within the range settings are included in the processed color palette. You can also specify how much emphasis to place on the range sensitivity. Because the palette has a maximum of 256 colors, emphasizing a focus color reduces the number of colors that fall outside the range sensitivity.


Palette types

CorelDRAW btnbacktotop Changing bitmaps to the paletted color mode

The table below outlines available palette types.

Palette type
Description
Uniform
Provides a range of 256 colors with equal parts of red, green, and blue
Standard VGA
Provides the Standard VGA 16-color palette
Adaptive
Provides colors original to the image and preserves the individual colors (the entire color spectrum) in the image
Optimized
Creates a color palette based on the highest percentage of colors in the image. You can also specify a range-sensitivity color for the color palette. This is the most common color palette for photographic images.
Black Body
Contains colors that are based on temperature. For example, black may represent cold temperatures, while red, orange, yellow, and white may represent hot temperatures.
Grayscale
Provides 256 shades of gray, ranging from black to white
System
Provides the predefined palette of colors used by the operating system
Web-safe
Provides a predefined palette of 216 non-dithered colors that will display the same on the Microsoft Internet Explorer and Netscape Navigator browsers. This palette is not recommended for use with photographs and only benefits users with older computers.
Custom
Lets you add colors to create a customized color palette


To change an image to the paletted color mode

CorelDRAW btnbacktotop Changing bitmaps to the paletted color mode
1.
 
Click a bitmap.
2.
 
Click Bitmaps CorelDRAW onestep Changing bitmaps to the paletted color mode Mode CorelDRAW onestep Changing bitmaps to the paletted color mode Paletted (8-bit).
3.
 
Click the Options tab.
4.
 
Choose a color palette type from the Palette list box.
5.
 
Choose an option from the Dithering list box.
6.
 
Move the Dithering intensity slider.
If you want to save the conversion settings as a preset, click the Add preset button, and type a name in the Save preset box.

CorelDRAW note Changing bitmaps to the paletted color mode

 
You can achieve better color fidelity by choosing the palette you want to use when you change an image to a paletted bitmap or when you export a GIF or PNG. For example, the standard color palette provides more colors than necessary for an image with a limited range of colors, but you can choose an optimized palette to ensure that color representation is accurate.

CorelDRAW tip Changing bitmaps to the paletted color mode

 
You can choose a custom color palette by clicking Open, locating the color palette file you want, and double-clicking the filename.
 
You can load preset conversion settings by choosing a preset from the Preset list box.

To create a custom processed color palette

CorelDRAW btnbacktotop Changing bitmaps to the paletted color mode
1.
 
Click a bitmap.
2.
 
Click Bitmaps CorelDRAW onestep Changing bitmaps to the paletted color mode Mode CorelDRAW onestep Changing bitmaps to the paletted color mode Paletted (8-bit).
3.
 
Click the Processed palette tab.
4.
 
Click a color, and click the Edit button.
5.
 
In the Color table, specify the color you want, and click Edit color.
6.
 
Edit the color, and click OK.
7.
 
Click the Save palette as button CorelDRAW pgx palsaveas button Changing bitmaps to the paletted color mode to save a new palette.
8.
 
Choose the disk and folder where you want to store the color palette.
9.
 
Type a name in the Name box, and click Save.

To change a bitmap by setting range sensitivity

CorelDRAW btnbacktotop Changing bitmaps to the paletted color mode
1.
 
Click a bitmap.
2.
 
Click Bitmaps CorelDRAW onestep Changing bitmaps to the paletted color mode Mode CorelDRAW onestep Changing bitmaps to the paletted color mode Paletted (8-bit).
3.
 
Click the Options tab.
4.
 
Choose Optimized from the Palette list box.
5.
 
Enable the Color range sensitivity to check box.
6.
 
Click the Eyedropper tool CorelDRAW pgx eyedropper tool Changing bitmaps to the paletted color mode , and click a color in the image.
7.
 
Click the Range sensitivity tab.
8.
 
Move the range sensitivity sliders.
If you want to preview the color palette, click the Processed palette tab.

Changing bitmaps to the paletted color mode