C# Class AForge.Imaging.Filters.SimpleQuadrilateralTransformation

Performs quadrilateral transformation of an area in the source image.

The class implements simple algorithm described by Olivier Thill for transforming quadrilateral area from a source image into rectangular image. The idea of the algorithm is based on finding for each line of destination rectangular image a corresponding line connecting "left" and "right" sides of quadrilateral in a source image. Then the line is linearly transformed into the line in destination image.

Due to simplicity of the algorithm it does not do any correction for perspective.

To make sure the algorithm works correctly, it is preferred if the "left-top" corner of the quadrilateral (screen coordinates system) is specified first in the list of quadrilateral's corners. At least user need to make sure that the "left" side (side connecting first and the last corner) and the "right" side (side connecting second and third corners) are not horizontal.

Use QuadrilateralTransformation to avoid the above mentioned limitations, which is a more advanced quadrilateral transformation algorithms (although a bit more computationally expensive).

The image processing filter accepts 8 grayscale images and 24/32 bpp color images for processing.

Sample usage:

 // define quadrilateral's corners List<IntPoint> corners = new List<IntPoint>( ); corners.Add( new IntPoint(  99,  99 ) ); corners.Add( new IntPoint( 156,  79 ) ); corners.Add( new IntPoint( 184, 126 ) ); corners.Add( new IntPoint( 122, 150 ) ); // create filter SimpleQuadrilateralTransformation filter = new SimpleQuadrilateralTransformation( corners, 200, 200 ); // apply the filter Bitmap newImage = filter.Apply( image );

Initial image:

Result image:

Inheritance: BaseTransformationFilter

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Protected Properties

Property	Type	Description
newHeight	int
newWidth	int

Public Methods

Method	Description
SimpleQuadrilateralTransformation ( ) : System	Initializes a new instance of the SimpleQuadrilateralTransformation class.
SimpleQuadrilateralTransformation ( List sourceQuadrilateral ) : System	Initializes a new instance of the SimpleQuadrilateralTransformation class. This constructor sets AutomaticSizeCalculaton to , which means that destination image will have width and height automatically calculated based on SourceQuadrilateral property.
SimpleQuadrilateralTransformation ( List sourceQuadrilateral, int newWidth, int newHeight ) : System	Initializes a new instance of the SimpleQuadrilateralTransformation class. This constructor sets AutomaticSizeCalculaton to , which means that destination image will have width and height as specified by user.

Protected Methods

Method	Description
CalculateNewImageSize ( UnmanagedImage sourceData ) : Size	Calculates new image size.
ProcessFilter ( UnmanagedImage sourceData, UnmanagedImage destinationData ) : void	Process the filter on the specified image.

Private Methods

Method	Description
CalculateDestinationSize ( ) : void

Method Details

CalculateNewImageSize() protected method

Calculates new image size.

Source quadrilateral was not set.

protected CalculateNewImageSize ( UnmanagedImage sourceData ) : Size
sourceData	UnmanagedImage	Source image data.
return	System.Drawing.Size

ProcessFilter() protected method

Process the filter on the specified image.

protected ProcessFilter ( UnmanagedImage sourceData, UnmanagedImage destinationData ) : void
sourceData	UnmanagedImage	Source image data.
destinationData	UnmanagedImage	Destination image data.
return	void

SimpleQuadrilateralTransformation() public method

Initializes a new instance of the SimpleQuadrilateralTransformation class.

public SimpleQuadrilateralTransformation ( ) : System
return	System

SimpleQuadrilateralTransformation() public method

Initializes a new instance of the SimpleQuadrilateralTransformation class.

This constructor sets AutomaticSizeCalculaton to , which means that destination image will have width and height automatically calculated based on SourceQuadrilateral property.

public SimpleQuadrilateralTransformation ( List sourceQuadrilateral ) : System
sourceQuadrilateral	List	Corners of the source quadrilateral area.
return	System

SimpleQuadrilateralTransformation() public method

Initializes a new instance of the SimpleQuadrilateralTransformation class.

This constructor sets AutomaticSizeCalculaton to , which means that destination image will have width and height as specified by user.

public SimpleQuadrilateralTransformation ( List sourceQuadrilateral, int newWidth, int newHeight ) : System
sourceQuadrilateral	List	Corners of the source quadrilateral area.
newWidth	int	Width of the new transformed image.
newHeight	int	Height of the new transformed image.
return	System

Property Details

newHeight protected_oe property

New image height.

protected int newHeight
return	int

newWidth protected_oe property

New image width.

protected int newWidth
return	int