Autotek autocad raster design 2010 用户手册

Vertical searches for vertical lines in a noisy image.

You can use these filters to clean up bitonal images.

Bitonal filters can be used in conjunction with other clean up commands,
such as despeckle and deskew. For more information, see 

 (page 84) and 

 (page 83).

You can use bitonal filters on an entire image, or on a portion of an image
called a sub-region. You can define a sub-region using one of four methods:

■

Use an existing closed vector entity to define the region.

■

Use an existing image clip.

■

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

■

Define a polygonal sub-region by clicking several points.

The smooth filter removes unnecessary pixels from the edges of raster objects,
fills holes in raster lines, and removes speckles from the raster image.

NOTE The smooth filter can eliminate small details in the image.

112 | Chapter 6   Modifying Images