Autotek autocad raster design 2010 用户手册

Toolspace Shortcut Menu

From color map object  ➤ Edit Color Map

Object Shortcut Menu

Properties, Color

Command Line

properties

You can make one color in each image transparent.

Making a color transparent is helpful if you want to see information that is
displayed behind the image. In a bitonal image, the transparency color is
always the background color of the image. For grayscale and color images,
you can choose the transparency color.

The transparency color is also used to replace data that is removed when you
edit an image using the rub or crop commands. If transparency is turned on
for the image, the rubbed areas (or the slack space in a cropped image) become
transparent. For more information, see 

 (page 144) and

 (page 149).

If you merge two images, the transparency color that is used to fill the space
between the two images depends upon the display order you specify in the

 (page 330).To use the transparency color of the first

image in the list for the fill color, click Image menu  ➤  Merge  ➤  Images.

Sometimes you may want to designate an unused color as the transparency
color. For instance, when merging images, turning on transparency may make
some desirable pixels transparent. The rbackground command allows you to
designate an unused color in a grayscale image as the transparency color.
Pixels with a value of 255 (white) are changed to a value of 254 (near white),
then the transparency color is set to a value of 255. The resulting image will
have no pixels with a value of 255.

NOTE Changing the transparency color does not affect the color of the existing
rubs and crops.

62 | Chapter 4   Changing Image Properties