Example Remove Perspective Distortion - Revision history

Peter at 22:56, 17 January 2022

2022-01-17T22:56:43Z

← Older revision		Revision as of 22:56, 17 January 2022
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.38/examples/src/main/java/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.40/examples/src/main/java/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:
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	public static void main( String[] args ) {		public static void main( String[] args ) {
	// load a color image		// load a color image
	BufferedImage buffered = UtilImageIO.~~loadImage~~(UtilIO.pathExample("goals_and_stuff.jpg"));		BufferedImage buffered = UtilImageIO.loadImageNotNull(UtilIO.pathExample("goals_and_stuff.jpg"));
	Planar<GrayF32> input = ConvertBufferedImage.convertFromPlanar(buffered, null, true, GrayF32.class);		Planar<GrayF32> input = ConvertBufferedImage.convertFromPlanar(buffered, null, true, GrayF32.class);

Peter at 18:16, 12 July 2021

2021-07-12T18:16:44Z

← Older revision		Revision as of 18:16, 12 July 2021
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.37/examples/src/main/java/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.38/examples/src/main/java/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:
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	/**		/**
	* Certain image processing techniques, such as Optical Character Recognition (OCR), can be performed better if		* Certain image processing techniques, such as Optical Character Recognition (OCR), can be performed better if
	* perspective distortion is remove from an image. In this example a homography is computed from the four corners		* perspective distortion is remove from an image. In this example a homography is computed from the four corners
	* of a bulletin board and the image is projected into a square image without perspective distortion. The		* of a bulletin board and the image is projected into a square image without perspective distortion. The
	* {@link RemovePerspectiveDistortion} class is used to perform the distortion. The class is easy to understand		* {@link RemovePerspectiveDistortion} class is used to perform the distortion. The class is easy to understand
	* if you know what a homography is, you should look at it!		* if you know what a homography is, you should look at it!
	*		*

Peter at 02:10, 22 December 2020

2020-12-22T02:10:26Z

← Older revision		Revision as of 02:10, 22 December 2020
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.27/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.37/examples/src/main/java/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:
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	*/		*/
	public class ExampleRemovePerspectiveDistortion {		public class ExampleRemovePerspectiveDistortion {
	public static void main(String[] args) {		public static void main( String[] args ) {

	// load a color image		// load a color image
	BufferedImage buffered = UtilImageIO.loadImage(UtilIO.pathExample("goals_and_stuff.jpg"));		BufferedImage buffered = UtilImageIO.loadImage(UtilIO.pathExample("goals_and_stuff.jpg"));
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	// Specify the corners in the input image of the region.		// Specify the corners in the input image of the region.
	// Order matters! top-left, top-right, bottom-right, bottom-left		// Order matters! top-left, top-right, bottom-right, bottom-left
	if( !removePerspective.apply(input,		if (!removePerspective.apply(input,
	new Point2D_F64(267, 182), new Point2D_F64(542, 68),		new Point2D_F64(267, 182), new Point2D_F64(542, 68),
	new Point2D_F64(519, 736), new Point2D_F64(276, 570)) ){		new Point2D_F64(519, 736), new Point2D_F64(276, 570))) {
	throw new RuntimeException("Failed!?!?");		throw new RuntimeException("Failed!?!?");
	}		}
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	Planar<GrayF32> output = removePerspective.getOutput();		Planar<GrayF32> output = removePerspective.getOutput();

	BufferedImage flat = ConvertBufferedImage.convertTo_F32(output,null,true);		BufferedImage flat = ConvertBufferedImage.convertTo_F32(output, null, true);
	ShowImages.showWindow(buffered,"Original Image",true);		ShowImages.showWindow(buffered, "Original Image", true);
	ShowImages.showWindow(flat,"Without Perspective Distortion",true);		ShowImages.showWindow(flat, "Without Perspective Distortion", true);
	}		}
	}		}

	</syntaxhighlight>		</syntaxhighlight>

Peter at 15:52, 17 August 2017

2017-08-17T15:52:15Z

← Older revision		Revision as of 15:52, 17 August 2017
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.25/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.27/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:
	* Homography		* Homography
	* ~~Perpsective~~		* Perspective
	* Distortion		* Distortion

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	// load a color image		// load a color image
	BufferedImage buffered = UtilImageIO.loadImage(UtilIO.pathExample("goals_and_stuff.jpg"));		BufferedImage buffered = UtilImageIO.loadImage(UtilIO.pathExample("goals_and_stuff.jpg"));
	Planar<GrayF32> input = ConvertBufferedImage.~~convertFromMulti~~(buffered, null, true, GrayF32.class);		Planar<GrayF32> input = ConvertBufferedImage.convertFromPlanar(buffered, null, true, GrayF32.class);

	RemovePerspectiveDistortion<Planar<GrayF32>> removePerspective =		RemovePerspectiveDistortion<Planar<GrayF32>> removePerspective =
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	}		}
	}		}

	</syntaxhighlight>		</syntaxhighlight>

Peter at 23:34, 1 December 2016

2016-12-01T23:34:11Z

← Older revision		Revision as of 23:34, 1 December 2016
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.23/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.25/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:
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	RemovePerspectiveDistortion<Planar<GrayF32>> removePerspective =		RemovePerspectiveDistortion<Planar<GrayF32>> removePerspective =
	new RemovePerspectiveDistortion<~~Planar<GrayF32>~~>(400,500, ImageType.pl(3,GrayF32.class));		new RemovePerspectiveDistortion<>(400, 500, ImageType.pl(3, GrayF32.class));

	// Specify the corners in the input image of the region.		// Specify the corners in the input image of the region.

Peter at 06:04, 28 March 2016

2016-03-28T06:04:44Z

← Older revision		Revision as of 06:04, 28 March 2016
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.20/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.23/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:
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	// load a color image		// load a color image
	BufferedImage buffered = UtilImageIO.loadImage(UtilIO.pathExample("goals_and_stuff.jpg"));		BufferedImage buffered = UtilImageIO.loadImage(UtilIO.pathExample("goals_and_stuff.jpg"));
	~~MultiSpectral~~<~~ImageFloat32~~> input = ConvertBufferedImage.convertFromMulti(buffered, null, true, ~~ImageFloat32~~.class);		Planar<GrayF32> input = ConvertBufferedImage.convertFromMulti(buffered, null, true, GrayF32.class);

	RemovePerspectiveDistortion<~~MultiSpectral~~<~~ImageFloat32~~>> removePerspective =		RemovePerspectiveDistortion<Planar<GrayF32>> removePerspective =
	new RemovePerspectiveDistortion<~~MultiSpectral~~<~~ImageFloat32~~>>(400,500, ImageType.ms(3,~~ImageFloat32~~.class));		new RemovePerspectiveDistortion<Planar<GrayF32>>(400,500, ImageType.pl(3,GrayF32.class));

	// Specify the corners in the input image of the region.		// Specify the corners in the input image of the region.
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	}		}

	~~MultiSpectral~~<~~ImageFloat32~~> output = removePerspective.getOutput();		Planar<GrayF32> output = removePerspective.getOutput();

	BufferedImage flat = ConvertBufferedImage.convertTo_F32(output,null,true);		BufferedImage flat = ConvertBufferedImage.convertTo_F32(output,null,true);

Peter at 17:41, 9 November 2015

2015-11-09T17:41:40Z

← Older revision		Revision as of 17:41, 9 November 2015
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.19/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.20/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:
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	/**		/**
	* Certain image processing techniques, such as Optical Character Recognition (OCR), can be performed better if		* Certain image processing techniques, such as Optical Character Recognition (OCR), can be performed better if
	* perspective distortion is remove from an image. In this example a homography is computed from the ~~cour~~ corners		* perspective distortion is remove from an image. In this example a homography is computed from the four corners
	* of a bulletin board and the image is projected into a square image without perspective distortion.		* of a bulletin board and the image is projected into a square image without perspective distortion. The
			* {@link RemovePerspectiveDistortion} class is used to perform the distortion. The class is easy to understand
			* if you know what a homography is, you should look at it!
	*		*
	* @author Peter Abeles		* @author Peter Abeles
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	// load a color image		// load a color image
	BufferedImage buffered = UtilImageIO.loadImage("~~../data/applet/~~goals_and_stuff.jpg");		BufferedImage buffered = UtilImageIO.loadImage(UtilIO.pathExample("goals_and_stuff.jpg"));
	MultiSpectral<ImageFloat32> input = ConvertBufferedImage.convertFromMulti(buffered, null, true, ImageFloat32.class);		MultiSpectral<ImageFloat32> input = ConvertBufferedImage.convertFromMulti(buffered, null, true, ImageFloat32.class);

	~~// Create a smaller output image for processing later on~~		RemovePerspectiveDistortion<MultiSpectral<ImageFloat32>> removePerspective =
	MultiSpectral<ImageFloat32> ~~output = input._createNew~~(400,500);		new RemovePerspectiveDistortion<MultiSpectral<ImageFloat32>>(400,500, ImageType.ms(3,ImageFloat32.class));

	// ~~Homography estimation algorithm~~. ~~Requires a minimum of 4 points~~		// Specify the corners in the input image of the region.
	~~Estimate1ofEpipolar computeHomography = FactoryMultiView~~.~~computeHomography~~(~~true~~);		// Order matters! top-left, top-right, bottom-right, bottom-left
			if( !removePerspective.apply(input,
			new Point2D_F64(267, 182), new Point2D_F64(542, 68),
			new Point2D_F64(519, 736), new Point2D_F64(276, 570)) ){
			throw new RuntimeException("Failed!?!?");
			}

	~~// Specify the pixel coordinates from destination to target~~		MultiSpectral<ImageFloat32> output = removePerspective.getOutput();
	~~ArrayList~~<~~AssociatedPair~~> ~~associatedPairs = new ArrayList<AssociatedPair>();~~
	~~associatedPairs.add(new AssociatedPair(new Point2D_F64(0,0),new Point2D_F64(267,182)));~~
	~~associatedPairs.add(new AssociatedPair(new Point2D_F64(output.width-1,0),new Point2D_F64(542,68)));~~
	~~associatedPairs.add(new AssociatedPair(new Point2D_F64(output.width-1,output.height-1),new Point2D_F64(519,736)));~~
	~~associatedPairs.add(new AssociatedPair(new Point2D_F64(0,~~output~~.height-1),new Point2D_F64(276,570)));~~

	~~// Compute the homography~~
	~~DenseMatrix64F H = new DenseMatrix64F(3,3);~~
	~~computeHomography.process(associatedPairs, H);~~

	~~// Create the transform for distorting the image~~
	~~PointTransformHomography_F32 homography = new PointTransformHomography_F32(H);~~
	~~PixelTransform_F32 pixelTransform~~ = ~~new PointToPixelTransform_F32(homography);~~

	~~// Apply distortion and show the results~~
	~~DistortImageOps~~.~~distortMS~~(~~input,output,pixelTransform, null, TypeInterpolate.BILINEAR~~);

	BufferedImage flat = ConvertBufferedImage.convertTo_F32(output,null,true);		BufferedImage flat = ConvertBufferedImage.convertTo_F32(output,null,true);

Peter at 19:01, 19 September 2015

2015-09-19T19:01:27Z

← Older revision		Revision as of 19:01, 19 September 2015
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.16/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.19/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:
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	// Apply distortion and show the results		// Apply distortion and show the results
	DistortImageOps.distortMS(input,output,pixelTransform,~~true~~, TypeInterpolate.BILINEAR);		DistortImageOps.distortMS(input,output,pixelTransform, null, TypeInterpolate.BILINEAR);

	BufferedImage flat = ConvertBufferedImage.convertTo_F32(output,null,true);		BufferedImage flat = ConvertBufferedImage.convertTo_F32(output,null,true);
	ShowImages.showWindow(buffered,"Original Image");		ShowImages.showWindow(buffered,"Original Image",true);
	ShowImages.showWindow(flat,"Without Perspective Distortion");		ShowImages.showWindow(flat,"Without Perspective Distortion",true);
	}		}
	}		}
	</syntaxhighlight>		</syntaxhighlight>

Peter at 00:32, 26 December 2013

2013-12-26T00:32:44Z

← Older revision		Revision as of 00:32, 26 December 2013
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.16/examples/src/boofcv/examples/~~imageprocessing~~/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.16/examples/src/boofcv/examples/geometry/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

	Concepts:		Concepts:

Peter: Created page with " file:Example_remove_perspective_input.jpg | Input file where the billboard is experiencing heavy perspective distortion. file:Exa..."

2013-12-26T00:28:04Z

Created page with "<center> <gallery widths=240px heights=320px> file:Example_remove_perspective_input.jpg | Input file where the billboard is experiencing heavy perspective distortion. file:Exa..."

New page

<center>
<gallery widths=240px heights=320px>
file:Example_remove_perspective_input.jpg | Input file where the billboard is experiencing heavy perspective distortion.
file:Example_remove_perspective_output.jpg| Output image after a homography is used to remap the billboard and remove perspective distortion.
</gallery>
</center>

It is often easier to process an image after perspective distortion is removed. The billboard in this example is at an acute angle relative to the camera, making its text hard to read. A homography can be created, using the for cornerns of the billboard, and used to remove this distortion.

Example Code:
* [https://github.com/lessthanoptimal/BoofCV/blob/v0.16/examples/src/boofcv/examples/imageprocessing/ExampleRemovePerspectiveDistortion.java ExampleRemovePerspectiveDistortion.java]

Concepts:
* Homography
* Perpsective
* Distortion

Relevant Examples:
* [[Example_Overhead_View|Example Overhead View]]

= Example Code =

<syntaxhighlight lang="java">
/**
* Certain image processing techniques, such as Optical Character Recognition (OCR), can be performed better if
* perspective distortion is remove from an image. In this example a homography is computed from the cour corners
* of a bulletin board and the image is projected into a square image without perspective distortion.
*
* @author Peter Abeles
*/
public class ExampleRemovePerspectiveDistortion {
public static void main(String[] args) {

// load a color image
BufferedImage buffered = UtilImageIO.loadImage("../data/applet/goals_and_stuff.jpg");
MultiSpectral<ImageFloat32> input = ConvertBufferedImage.convertFromMulti(buffered, null, true, ImageFloat32.class);

// Create a smaller output image for processing later on
MultiSpectral<ImageFloat32> output = input._createNew(400,500);

// Homography estimation algorithm. Requires a minimum of 4 points
Estimate1ofEpipolar computeHomography = FactoryMultiView.computeHomography(true);

// Specify the pixel coordinates from destination to target
ArrayList<AssociatedPair> associatedPairs = new ArrayList<AssociatedPair>();
associatedPairs.add(new AssociatedPair(new Point2D_F64(0,0),new Point2D_F64(267,182)));
associatedPairs.add(new AssociatedPair(new Point2D_F64(output.width-1,0),new Point2D_F64(542,68)));
associatedPairs.add(new AssociatedPair(new Point2D_F64(output.width-1,output.height-1),new Point2D_F64(519,736)));
associatedPairs.add(new AssociatedPair(new Point2D_F64(0,output.height-1),new Point2D_F64(276,570)));

// Compute the homography
DenseMatrix64F H = new DenseMatrix64F(3,3);
computeHomography.process(associatedPairs, H);

// Create the transform for distorting the image
PointTransformHomography_F32 homography = new PointTransformHomography_F32(H);
PixelTransform_F32 pixelTransform = new PointToPixelTransform_F32(homography);

// Apply distortion and show the results
DistortImageOps.distortMS(input,output,pixelTransform,true, TypeInterpolate.BILINEAR);

BufferedImage flat = ConvertBufferedImage.convertTo_F32(output,null,true);
ShowImages.showWindow(buffered,"Original Image");
ShowImages.showWindow(flat,"Without Perspective Distortion");
}
}
</syntaxhighlight>