Autotek autocad raster design 2010 用户手册

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Convolve. Use 

 (page 398) and 

 (page 396)

to improve the appearance of your image. Smoothing filters reduce
harshness and noise in your image. Sharpening filters make differences in
shading more distinct.

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Bitonal Filters. Smooth the appearance of raster lines or separate partially
merged raster lines.

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Change Density. Increase or decrease the resolution of an image.

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Change Color Depth. Increase or decrease the color depth of an image.
For instance, you can change an 8-bit grayscale image to a bitonal image.

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Palette Manager. Change colors or shades of gray in an 8-bit image, import
and export palettes.

NOTE Raster Design uses 

 (page 396) to speed up the

editing commands.

You can use the Histogram to adjust the brightness and contrast of an image,
to maximize detail, to convert color or grayscale images to bitonal, and to
convert color images to grayscale.

The Histogram changes the image data definition, so all future insertions of
the image include these changes. If you want to just change brightness and
contrast of a particular insertion, you can change the color map. For more
information, see 

 (page 68).

You can adjust a whole image or a sub-region. You can define a sub-region
using one of four methods:

■

Use an existing closed vector entity to define the sub-region.

■

Use an existing image clip.

■

Define a rectangular sub-region by clicking two-points.

■

Define a polygonal sub-region by clicking several points.

You can permanently change the tone and visibility of images.

92 | Chapter 6   Modifying Images