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.
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:
private Bitmap processImage(Bitmap img)
{
//Generate closing structural element
short[,] structEl = new short[13, 13];
for (int i = 0; i < 13; i++)
for (int j = 0; j < 13; j++)
if ((i - 6) * (i - 6) + (j - 6) * (j - 6) < 64)
structEl[i, j] = 1;
else
structEl[i, j] = -1;
//Initialize filters
HSLFiltering borderFind = new HSLFiltering();
Closing borderClose = new Closing(structEl);
Invert invert = new Invert();
Grayscale grayFilter = new Grayscale(0, 0, 1.0);
Threshold bwFilter = new Threshold(1);
PointedColorFloodFill blackout = new PointedColorFloodFill();
blackout.Tolerance = Color.FromArgb(0, 0, 0);
blackout.FillColor = Color.FromArgb(0, 0, 0);
ExtractBiggestBlob getgame = new ExtractBiggestBlob();
getgame.OriginalImage = new Bitmap(img);
GrayscaleToRGB colorFilter = new GrayscaleToRGB();
//Color determined with ColorProbe.
borderFind.Hue = new IntRange(190, 200);
borderFind.Saturation = new Range(0.6f, 0.8f);
borderFind.Luminance = new Range(0.6f, 1.0f);
borderFind.ApplyInPlace(img);
borderClose.ApplyInPlace(img);
img = grayFilter.Apply(img);
bwFilter.ApplyInPlace(img);
invert.ApplyInPlace(img);
img = colorFilter.Apply(img);
blackout.StartingPoint = new AForge.IntPoint(0, 0);
blackout.ApplyInPlace(img);
img = getgame.Apply(img);
int tilesx = img.Width / 56;
int tilesy = img.Height / 56;
int offsetx = 56 * (int)(tilesx - img.Width / 56.0);
int offsety = 56 * (int)(tilesy - img.Height / 56.0);
if ((Math.Abs(offsetx) > 11) || (Math.Abs(offsety) > 11))
throw new GameNotFoundException();
List<IntPoint> corners = new List<IntPoint>();
Dictionary<IntPoint, Bitmap> tiles = new Dictionary<IntPoint, Bitmap>();
SimpleQuadrilateralTransformation tileXtract = new SimpleQuadrilateralTransformation();
for (int j = 0; j < tilesy; j++)
for (int i = 0; i < tilesx; i++)
{
corners.Add(new IntPoint(offsetx + i * 56, offsety + j * 56 ));
corners.Add(new IntPoint(offsetx + i * 56, offsety + (j + 1) * 56 - 1));
corners.Add(new IntPoint(offsetx + (i + 1) * 56 - 1, offsety + (j + 1) * 56 - 1));
corners.Add(new IntPoint(offsetx + (i + 1) * 56 - 1, offsety + j * 56 ));
tileXtract.SourceQuadrilateral = corners;
tiles.Add(new IntPoint(i, j), tileXtract.Apply(img));
corners.Clear();
}
img = (Bitmap)Properties.Resources.ResourceManager.GetObject("cb");
/*Graphics g = Graphics.FromImage(img);
Pen bluePen = new Pen(Color.Blue, 2);
for (int i = 0, n = blobs.Length; i < n; i++)
{
List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blobs[i]);
if (edgePoints.Count > 1)
{
List<IntPoint> corners = PointsCloud.FindQuadrilateralCorners(edgePoints);
g.DrawPolygon(bluePen, ToPointsArray(corners));
}
}
bluePen.Dispose();
g.Dispose();
*/
return img;
}
/// <summary>
/// Initializes a new instance of the <see cref="QuadrilateralTransformationNearestNeighbor"/> class.
/// </summary>
///
/// <param name="sourceCorners">Corners of the source quadrilateral area.</param>
///
/// <remarks><para>This constructor sets <see cref="AutomaticSizeCalculaton"/> to
/// <see langword="true"/>, which means that destination image will have width and
/// height automatically calculated based on <see cref="SourceCorners"/> property.</para></remarks>
///
public QuadrilateralTransformationNearestNeighbor(List <IntPoint> sourceCorners)
{
baseFilter = new SimpleQuadrilateralTransformation(sourceCorners)
{
UseInterpolation = false
};
}
/// <summary>
/// Initializes a new instance of the <see cref="QuadrilateralTransformationBilinear"/> class.
/// </summary>
///
/// <param name="sourceCorners">Corners of the source quadrilateral area.</param>
///
/// <remarks><para>This constructor sets <see cref="AutomaticSizeCalculaton"/> to
/// <see langword="true"/>, which means that destination image will have width and
/// height automatically calculated based on <see cref="SourceCorners"/> property.</para></remarks>
///
public QuadrilateralTransformationBilinear(List <IntPoint> sourceCorners)
{
baseFilter = new SimpleQuadrilateralTransformation(sourceCorners)
{
UseInterpolation = true
};
}
/// <summary>
/// Initializes a new instance of the <see cref="QuadrilateralTransformationBilinear"/> class.
/// </summary>
///
/// <param name="sourceCorners">Corners of the source quadrilateral area.</param>
/// <param name="newWidth">Width of the new transformed image.</param>
/// <param name="newHeight">Height of the new transformed image.</param>
///
/// <remarks><para>This constructor sets <see cref="AutomaticSizeCalculaton"/> to
/// <see langword="false"/>, which means that destination image will have width and
/// height as specified by user.</para></remarks>
///
public QuadrilateralTransformationBilinear(List <IntPoint> sourceCorners, int newWidth, int newHeight)
{
baseFilter = new SimpleQuadrilateralTransformation(sourceCorners, newWidth, newHeight);
baseFilter.UseInterpolation = true;
}
/// <summary>
/// Initializes a new instance of the <see cref="QuadrilateralTransformationNearestNeighbor"/> class.
/// </summary>
///
/// <param name="sourceCorners">Corners of the source quadrilateral area.</param>
/// <param name="newWidth">Width of the new transformed image.</param>
/// <param name="newHeight">Height of the new transformed image.</param>
///
/// <remarks><para>This constructor sets <see cref="AutomaticSizeCalculaton"/> to
/// <see langword="false"/>, which means that destination image will have width and
/// height as specified by user.</para></remarks>
///
public QuadrilateralTransformationNearestNeighbor(List <IntPoint> sourceCorners, int newWidth, int newHeight)
{
this.baseFilter = new SimpleQuadrilateralTransformation(sourceCorners, newWidth, newHeight);
this.baseFilter.UseInterpolation = false;
}
/// <summary>
/// Initializes a new instance of the <see cref="QuadrilateralTransformationNearestNeighbor"/> class.
/// </summary>
///
/// <param name="sourceCorners">Corners of the source quadrilateral area.</param>
///
/// <remarks><para>This constructor sets <see cref="AutomaticSizeCalculaton"/> to
/// <see langword="true"/>, which means that destination image will have width and
/// height automatically calculated based on <see cref="SourceCorners"/> property.</para></remarks>
///
public QuadrilateralTransformationNearestNeighbor( List<IntPoint> sourceCorners )
{
baseFilter = new SimpleQuadrilateralTransformation( sourceCorners );
baseFilter.UseInterpolation = false;
}
/// <summary>
/// Initializes a new instance of the <see cref="QuadrilateralTransformationBilinear"/> class.
/// </summary>
///
/// <param name="sourceCorners">Corners of the source quadrilateral area.</param>
///
/// <remarks><para>This constructor sets <see cref="AutomaticSizeCalculaton"/> to
/// <see langword="true"/>, which means that destination image will have width and
/// height automatically calculated based on <see cref="SourceCorners"/> property.</para></remarks>
///
public QuadrilateralTransformationBilinear( List<IntPoint> sourceCorners )
{
baseFilter = new SimpleQuadrilateralTransformation( sourceCorners );
baseFilter.UseInterpolation = true;
}
