Using the Aliasing/Anti-aliasing Tool to Enhance Display of Your Images

This Tech Tip appeared in Imaging News May 2005.

Snowbound Software’s FlexSnap web viewer and SnowView have several features that allow you to change the appearance of an image. One of these tools is the Alias/Anti-alias tool. This tech tip describes how to use the Alias/Anti-alias tool to improve the appearance of an image.

Aliasing is a process by which smooth curves and other lines become jagged because the resolution of the display or the graphic file is not high enough to represent a smooth curve.
Anti-aliasing is a software technique used to diminish 'step-like' lines that should be smooth. Anti-aliasing surrounds stair steps with intermediate shades of gray, or gray scaling, for 1-bit images or color for color images.

The image below shows an example of aliasing and anti-aliasing:

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FlexSnap’s Alias/Anti-alias Tool

In Snowbound Software's FlexSnap Applet, you can anti-alias images by using the Anti-alias feature. To turn aliasing on, select Preferences>Anti-alias>Scale to Gray or Preserve Black from the menu. This feature only works for black and white 1-bit images.

To turn aliasing off, select Preferences>Anti-alias>Off from the menu. This feature only works for black and white 1-bit images.

SnowView’s Alias/Anti-alias Tool

In Snowbound's SnowView application, aliasing can be turned on or off by doing the following:

1. Choose View > Aliasing (This displays the Alias dialog.)
2. In the Type field, select None, Preserve Black, Scale to Gray, or Quality. (See the table below for a description of each alias type.)

Alias Type	Description
None	Aliasing is not turned on.
Preserve Black	Checks neighboring pixels for any black so that any small black lines are not removed when scaling a large black and white image. The Preserve Black option is typically recommended for large schematics and engineering drawings.
Scale to Gray	Converts the image to gray scale values when displaying a large image. The Scale to Gray option is typically recommended for documents.
Quality	Higher quality setting improves the quality of 1-bit (B&W) images.

3. Click OK to accept the changes, or click Cancel to avoid making any changes.