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Remove Shear
Since an angle of 90 degrees is normally retained when an image is skewed,
the image can be deskewed simply by rotating it. However, there are times
when the images are distorted. In cases like this, a process of simple rotation
can align the top and bottom or left and right edges, but it cannot eliminate the
distortion itself. This kind of distortion sometimes arises in a scanner or fax
machine which moves the documents.
Processing the #1 image with the Deskew image filter produces an image
resembling #2. When Remove Shear is enabled, the Deskew image filter
eliminates the distortion in the direction selected under Measurement Direction.
When Remove Shear is not enabled, only rotation is used to adjust the skew.
If an image is skewed by both rotation and distortion, two Deskew image filters
must be used. One is used to remove the skew of the rotation and the other to
remove the distortion. Use an actual document to see which of the two is better
used first.
In order to obtain the best results, select Graphics so that the amount of
distortion can be detected from the ruled lines and other factors. Otherwise, the
results may be adversely affected by the font style or italicized text.
IMPORTANT NOTE:
•
To eliminate distortion rather than rotation, be absolutely sure to select one (not
both) of the Measurement Direction settings and set the [Remove Shear] check
box to on. If the check box is not set to on, only the rotation will be corrected. Use
this check box only when [Graphic] has been selected as the skew criterion.
#1- Image is distorted hori-
zontally and rotated.
#2- Image is distorted hori-
zontally but not rotated.