Correcting Geometric Distortions

Correcting Geometric Distortions

This chapter describes the procedures that allow the user to correct various geometric distortions of monochrome, colour and greyscale raster images. Such operations are recommended, and even necessary, before applying more complicated procedures such as layering or vectorization. For example, if an original raster image is distorted, after vectorization a vector drawing is produced that may be impossible to correct. The calibration procedure can be used to eliminate deformations before applying vectorization.
This chapter describes the procedures that process an entire image.

This chapter describes the procedures that process an entire image.
Use them to:
• Change an image size (this command modifies an image geometry by adding or cropping margins, its contents and resolution are left intact);
• Resample an image (this command modifies an image geometry by changing its resolution or size in pixels);
• Crop an image;
• Mirror an image about vertical or horizontal axis;
• Rotate an image by an arbitrary angle;
• Deskew image manually or automatically;
• Correct trapezoid, parallelogram, and projective image distortions using four-point correction;
• Eliminate arbitrary (both linear and non-linear) deformation using calibration.

The table below shows the more valid targets for raster correcting operations.

A1	Clipped images	Multiple images
Auto Correct
Change Size
Resample
Image Clip
Crop by Clip
Crop
Mirror
Rotate
Deskew
Four Point Correction
Calibration