/// <summary>
/// Applies blob Processing on the image and extracts blobs corresponding to the bubbles and return them as a blob array.
/// <param name="bitmap">Pre Processed Image</param>
/// </summary>
public static List <Blob> ExtractBubbleCorrespondingBlobs(Bitmap bitmap, int minblobwidth, int minblobheight)
{
Bitmap bm = new Bitmap(bitmap.Size.Width, bitmap.Size.Height);
Graphics g = Graphics.FromImage(bm);
g.DrawImage(bitmap, new Rectangle(0, 0, bitmap.Width, bitmap.Height));
Pen redpen = new Pen(Color.Red, 3);
AForge.Math.Geometry.SimpleShapeChecker detectshape = new AForge.Math.Geometry.SimpleShapeChecker();
// lock the image
BitmapData bitmapdata = bitmap.LockBits(
new Rectangle(0, 0, bitmap.Width, bitmap.Height),
ImageLockMode.ReadWrite, bitmap.PixelFormat);
// Finding Blobs in the Bitmap image
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinHeight = minblobheight;
blobCounter.MinWidth = minblobwidth;
blobCounter.ProcessImage(bitmapdata);
Blob[] blobs = blobCounter.GetObjectsInformation();
bitmap.UnlockBits(bitmapdata);
//Rectangle[] rects = blobCounter.GetObjectsRectangles();
Blob[] blob_objects = blobCounter.GetObjects(bitmap, false);
List <Blob> bubblesblobs = new List <Blob>();
try
{
foreach (Blob blob in blob_objects)
{
//detect circles through aspect ratio
if ((double)blob.Rectangle.Width / blob.Rectangle.Height < 1.4 &&
(double)blob.Rectangle.Width / blob.Rectangle.Height > .6) // filters out blobs having insanely wrong aspect ratio
{
List <IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blob);
detectshape.MinAcceptableDistortion = 0.5f; //0.5f;
detectshape.RelativeDistortionLimit = 0.079f; //0.057f;
AForge.Point center;
float radius;
//detect circles only
if (detectshape.IsCircle(edgePoints, out center, out radius))
{
//detect filled bubbles only
if ((blob.Fullness > 0.60) && ((double)blob.Image.Width / (double)bitmap.Size.Width > 0.014))
{
//g.DrawEllipse(redpen,
// (int)(center.X - radius),
// (int)(center.Y - radius),
// (int)(radius * 2),
// (int)(radius * 2));
bubblesblobs.Add(blob);
}
}
}
}
return(bubblesblobs);
}
catch (ArgumentException) { MessageBox.Show("Bubble Detection Failed"); }
return(null);
}
public static Bitmap ExtractPaperFromFlattened(Bitmap bitmap, Bitmap originalimage, int minblobwidth, int minblobheight, bool applyrotation)
{
Bitmap bm = new Bitmap(bitmap.Size.Width, bitmap.Size.Height);
Graphics g = Graphics.FromImage(bm);
g.DrawImage(bitmap, new Rectangle(0, 0, bitmap.Width, bitmap.Height));
Pen redpen = new Pen(Color.Red, 2);
AForge.Math.Geometry.SimpleShapeChecker detectshape = new AForge.Math.Geometry.SimpleShapeChecker();
if (applyrotation)
{
//rotate the image in case it is not properly oriented
// lock the image
BitmapData bitmapdata_rot = bitmap.LockBits(
new Rectangle(0, 0, bitmap.Width, bitmap.Height),
ImageLockMode.ReadWrite, bitmap.PixelFormat);
BlobCounter blobCounter_rot = new BlobCounter();
blobCounter_rot.FilterBlobs = true;
blobCounter_rot.MinHeight = minblobheight;
blobCounter_rot.MinWidth = minblobwidth;
blobCounter_rot.ProcessImage(bitmapdata_rot);
bitmap.UnlockBits(bitmapdata_rot);
Blob[] blob_objects_rot = blobCounter_rot.GetObjects(bitmap, false);
try
{
foreach (Blob blob in blob_objects_rot)
{
List <IntPoint> edgePoints = blobCounter_rot.GetBlobsEdgePoints(blob);
//detect rotated paper based on left edge rectangular mark
List <IntPoint> cornerPoints;
if (detectshape.IsQuadrilateral(edgePoints, out cornerPoints))
{
if (detectshape.CheckPolygonSubType(cornerPoints) == AForge.Math.Geometry.PolygonSubType.Rectangle)
{
if ((blob.Fullness > 0.7) && (((double)blob.Image.Width / (double)bitmap.Size.Width > 0.025) && ((double)blob.Image.Width / (double)bitmap.Size.Width < 0.037)) && (((double)blob.Image.Height / (double)bitmap.Size.Height > 0.005) && ((double)blob.Image.Height / (double)bitmap.Size.Height < 0.013)))
{
// A------p------B Suppose these are the Coordinates of the Rectangle (image)
// | 2 | 1 | A,B,C,D are vertices and 1,2,3,4 are quadrants
// s------O------q p,q,r,s midpoints
// | 3 | 4 | O is the center of the rectangle
// D------r------C let the blob be denoted by BL
System.Drawing.Point cent_O = new System.Drawing.Point(bitmap.Size.Width / 2, bitmap.Size.Height / 2);
GraphicsUnit units = GraphicsUnit.Point;
System.Drawing.Point pnt_A = new System.Drawing.Point((int)bitmap.GetBounds(ref units).X, (int)bitmap.GetBounds(ref units).Y);
System.Drawing.Point pnt_B = new System.Drawing.Point(bitmap.Size.Width, (int)bitmap.GetBounds(ref units).Y);
System.Drawing.Point pnt_C = new System.Drawing.Point(bitmap.Size.Width, bitmap.Size.Height);
System.Drawing.Point pnt_D = new System.Drawing.Point((int)bitmap.GetBounds(ref units).X, bitmap.Size.Height);
System.Drawing.Point midpnt_P = new System.Drawing.Point((pnt_A.X + pnt_B.X) / 2, (pnt_A.Y + pnt_B.Y) / 2);
System.Drawing.Point midpnt_Q = new System.Drawing.Point((pnt_B.X + pnt_C.X) / 2, (pnt_B.Y + pnt_C.Y) / 2);
System.Drawing.Point midpnt_R = new System.Drawing.Point((pnt_C.X + pnt_D.X) / 2, (pnt_C.Y + pnt_D.Y) / 2);
System.Drawing.Point midpnt_S = new System.Drawing.Point((pnt_A.X + pnt_D.X) / 2, (pnt_A.Y + pnt_D.Y) / 2);
System.Drawing.Point blob_CENGRAV = new System.Drawing.Point((int)blob.CenterOfGravity.X, (int)blob.CenterOfGravity.Y);
if (ImageProcessor.IsPointInsideRegion(bitmap, pnt_A, midpnt_P, cent_O, midpnt_S, blob_CENGRAV))
{
//do nothing...image is properly oriented
break; //terminate the loop
}
else if (ImageProcessor.IsPointInsideRegion(bitmap, midpnt_P, pnt_B, midpnt_Q, cent_O, blob_CENGRAV))
{
//blob is present in quadrant 1
//rotate image by three CW
bitmap.RotateFlip(RotateFlipType.Rotate270FlipNone);
originalimage.RotateFlip(RotateFlipType.Rotate270FlipNone);
break;
}
else if (ImageProcessor.IsPointInsideRegion(bitmap, cent_O, midpnt_Q, pnt_C, midpnt_R, blob_CENGRAV))
{
//blob is present in quadrant 4
//rotate image by two CW
bitmap.RotateFlip(RotateFlipType.Rotate180FlipNone);
originalimage.RotateFlip(RotateFlipType.Rotate180FlipNone);
break;
}
else if (ImageProcessor.IsPointInsideRegion(bitmap, cent_O, midpnt_R, pnt_D, midpnt_S, blob_CENGRAV))
{
//blob is present in quadrant 3
//rotate image by one CW
bitmap.RotateFlip(RotateFlipType.Rotate90FlipNone);
originalimage.RotateFlip(RotateFlipType.Rotate90FlipNone);
break;
}
}
}
}
}
}
catch (ArgumentException) { MessageBox.Show("Bilinear Rotational Transformation Failed"); }
}
//After applying rotational process, extract the blobs once again to find the circular edge markers
// lock the image
BitmapData bitmapdata = bitmap.LockBits(
new Rectangle(0, 0, bitmap.Width, bitmap.Height),
ImageLockMode.ReadWrite, bitmap.PixelFormat);
// Finding Blobs in the Bitmap image
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinHeight = minblobheight;
blobCounter.MinWidth = minblobwidth;
blobCounter.ProcessImage(bitmapdata);
Blob[] blobs = blobCounter.GetObjectsInformation();
bitmap.UnlockBits(bitmapdata);
//Rectangle[] rects = blobCounter.GetObjectsRectangles();
Blob[] blob_objects = blobCounter.GetObjects(bitmap, false);
// Paper Detection happens through the detection of the edge-markers placed on all four
// edges of the OMR sheet
List <IntPoint> quad = new List <IntPoint>(); // Store sheet corner locations (if anyone is detected )
try
{
foreach (Blob blob in blob_objects)
{
//detect edge circles
if ((double)blob.Rectangle.Width / blob.Rectangle.Height < 1.4 &&
(double)blob.Rectangle.Width / blob.Rectangle.Height > .6) // filters out blobs having insanely wrong aspect ratio
{
List <IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blob);
//detect circles only
if (detectshape.IsCircle(edgePoints))
{
//detect filled circles only
//the ratio of width(blob)/width(bitmap) should be in range of 0.031 - 0.042
if ((blob.Fullness > 0.7) && (((double)blob.Image.Width / (double)bitmap.Width) > 0.031) && (((double)blob.Image.Width / (double)bitmap.Width) < 0.042))
{
//g.DrawRectangle(redpen, blob.Rectangle);
quad.Add(new IntPoint((int)blob.CenterOfGravity.X, (int)blob.CenterOfGravity.Y));
}
}
}
}
// filter out if wrong blobs pretend to be our blobs.
if (quad.Count == 4)
{
if (!((quad[0].DistanceTo(quad[1]) / quad[0].DistanceTo(quad[2]) > 0.5) &&
(quad[0].DistanceTo(quad[1]) / quad[0].DistanceTo(quad[2]) < 1.5)))
{
quad.Clear();
}
else
{
//rearrange the edge coordinates, if not in proper manner
while ((quad[0].X > quad[1].X) || (quad[1].Y > quad[3].Y) || (quad[2].X > quad[3].X) || (quad[0].Y > quad[2].Y))
{
if (quad[0].X > quad[1].X)
{
IntPoint tmp = quad[0];
quad[0] = quad[1];
quad[1] = tmp;
}
if (quad[1].Y > quad[3].Y)
{
IntPoint tmp = quad[1];
quad[1] = quad[3];
quad[3] = tmp;
}
if (quad[2].X > quad[3].X)
{
IntPoint tmp = quad[3];
quad[3] = quad[2];
quad[2] = tmp;
}
if (quad[0].Y > quad[2].Y)
{
IntPoint tmp = quad[0];
quad[0] = quad[2];
quad[2] = tmp;
}
}
}
}
if (quad.Count != 4)
{
//call recursively as the sheet is not detected properly
//todo: try altering the blob height and width, threshold etc, when program does not find edge markers
}
else
{
//rearrange the edges coordinates
// 0----1
// | |
// 2----3
//interchange 2 and 3
IntPoint tp2 = quad[3];
quad[3] = quad[2];
quad[2] = tp2;
//sort the edges for wrap operation
QuadrilateralTransformation wrap = new QuadrilateralTransformation(quad, 2100, 2970);
wrap.UseInterpolation = false;
wrap.AutomaticSizeCalculaton = true;
Bitmap wrappedoriginal = wrap.Apply(originalimage);
return(wrappedoriginal);
}
}
catch (ArgumentException) { MessageBox.Show("No Blobs Found"); }
return(null);
}
