private void LoadImage(string filePath)
{
try
{
using (Mat image = new Mat(filePath))
using (Mat resized = image.Resize(GetTargetSize(image.Size()))) //Scale the image, so we are working with something consistent
{
AddImage(resized);
using (Mat gray = resized.CvtColor(ColorConversionCodes.BGR2GRAY)) //Convert to gray scale since we don't want the color data
using (Mat blur = gray.GaussianBlur(new Size(5, 5), 0)) //Smooth the image to eliminate noise
using (Mat autoCanny = blur.AutoCanny()) //Apply canny edge filter to find edges
using (Mat structuringElement = Cv2.GetStructuringElement(MorphShapes.Ellipse, new Size(9, 9)))
{
AddImage(autoCanny);
//Smooth over small possible breaks in edges
Cv2.Dilate(autoCanny, autoCanny, structuringElement);
AddImage(autoCanny);
Cv2.Erode(autoCanny, autoCanny, structuringElement);
AddImage(autoCanny);
//Change the RetrievalModes to CComp if you want internal polygons too, not just the outer most one.
Point[][] contours = autoCanny.FindContoursAsArray(RetrievalModes.External, ContourApproximationModes.ApproxSimple);
//Draw all of the found polygons for reference
using (Mat allFound = resized.Clone())
{
for (int i = 0; i < contours.Length; i++)
{
Cv2.DrawContours(allFound, contours, i, Scalar.RandomColor(), 2);
}
AddImage(allFound);
}
//Find the largest polygons that four corners
var found = (from contour in contours
let permimiter = Cv2.ArcLength(contour, true)
let approx = Cv2.ApproxPolyDP(contour, 0.04 * permimiter, true)
where approx.Length == 4 //Rectange
let area = Cv2.ContourArea(approx)
orderby area descending //We are looking for the biggest thing
select approx).Take(3).ToArray(); //Grabbing three just for comparison
//Colors the found polygons Green->Yellow->Red to indicate best matches.
for (int i = 0; i < found.Length; i++)
{
Scalar color;
switch (i)
{
case 0:
color = Scalar.Green;
break;
case 1:
color = Scalar.Yellow;
break;
case 2:
color = Scalar.Red;
break;
default:
color = Scalar.RandomColor();
break;
}
resized.DrawContours(found, i, color, 3);
}
AddImage(resized);
}
}
}
catch (Exception e)
{
Debug.WriteLine(e.ToString());
}
Size GetTargetSize(Size size, int longSize = 512)
{
if (size.Width > size.Height)
{
return(new Size(longSize, (int)(longSize * (double)size.Height / size.Width)));
}
return(new Size((int)(longSize * (double)size.Width / size.Height), longSize));
}
}
private void LoadImage(string filePath)
{
//using (Mat mat1 = Mat.Zeros(2048, 1536, MatType.CV_8UC1))
//using (Mat mat2 = Mat.Zeros(2048, 1536, MatType.CV_8UC1))
//using (var intersection = new Mat(2048, 1536, MatType.CV_8UC1))
//using (var union = new Mat(2048, 1536, MatType.CV_8UC1))
//{
// mat1.FillPoly(new[] { new[]
// {
// new Point(565, 267),
// new Point(1210, 207),
// new Point(1275, 1720),
// new Point(568, 1688)
// } }, Scalar.All(255));
// AddImage(mat1);
// mat2.FillPoly(new[] { new[]
// {
// new Point(564, 268),
// new Point(1208, 208),
// new Point(1272, 1716),
// new Point(572, 1688)
// } }, Scalar.All(255));
// AddImage(mat2);
// Cv2.BitwiseAnd(mat1, mat2, intersection);
// int intersectionPixels = Cv2.CountNonZero(intersection);
// AddImage(intersection);
// Cv2.BitwiseOr(mat1, mat2, union);
// int unionPixels = Cv2.CountNonZero(union);
// AddImage(union);
// double iou = (double) intersectionPixels / unionPixels;
//}
//
//return;
try
{
using (Mat image = new Mat(filePath))
using (Mat resized = image.Resize(GetTargetSize(image.Size()))) //Scale the image, so we are working with something consistent
{
AddImage(resized);
using (Mat gray = resized.CvtColor(ColorConversionCodes.BGRA2GRAY)) //Convert to gray scale since we don't want the color data
using (Mat blur = gray.GaussianBlur(new Size(5, 5), 0, borderType: BorderTypes.Replicate)) //Smooth the image to eliminate noise
using (Mat autoCanny = blur.AutoCanny(0.75)) //Apply canny edge filter to find edges
{
AddImage(blur);
AddImage(autoCanny);
Point[][] contours = autoCanny.FindContoursAsArray(RetrievalModes.List, ContourApproximationModes.ApproxSimple);
//Just get the external hull of the contours
for (int i = 0; i < contours.Length; i++)
{
contours[i] = Cv2.ConvexHull(contours[i]);
}
//Draw all of the found polygons. This is just for reference
using (Mat allFound = resized.Clone())
{
for (int i = 0; i < contours.Length; i++)
{
Cv2.DrawContours(allFound, contours, i, Scalar.RandomColor(), 2);
}
AddImage(allFound);
}
//Find the largest polygons that four corners
var found = (from contour in contours
let permimiter = Cv2.ArcLength(contour, true)
let approx = Cv2.ApproxPolyDP(contour, 0.02 * permimiter, true)
where IsValidRectangle(approx, 0.2)
let area = Cv2.ContourArea(contour)
orderby area descending //We are looking for the biggest thing
select contour).Take(3).ToArray(); //Grabbing three just for comparison
//Colors the found polygons Green->Yellow->Red to indicate best matches.
for (int i = found.Length - 1; i >= 0; i--)
{
Scalar color;
switch (i)
{
case 0:
color = Scalar.Green;
break;
case 1:
color = Scalar.Yellow;
break;
case 2:
color = Scalar.Red;
break;
default:
color = Scalar.RandomColor();
break;
}
resized.DrawContours(found, i, color, 3);
}
AddImage(resized);
}
}
}
catch (Exception e)
{
Debug.WriteLine(e.ToString());
}
bool IsValidRectangle(Point[] contour, double minimum)
{
if (contour.Length != 4)
{
return(false);
}
double side1 = GetLength(contour[0], contour[1]);
double side2 = GetLength(contour[1], contour[2]);
double side3 = GetLength(contour[2], contour[3]);
double side4 = GetLength(contour[3], contour[0]);
if (Math.Abs(side1 - side3) / Math.Max(side1, side3) > minimum)
{
return(false);
}
if (Math.Abs(side2 - side4) / Math.Max(side2, side4) > minimum)
{
return(false);
}
return(true);
double GetLength(Point p1, Point p2) => Math.Abs(p1.X - p2.X) + Math.Abs(p1.Y - p2.Y);
}
Size GetTargetSize(Size size, int longSize = 512)
{
if (size.Width > size.Height)
{
return(new Size(longSize, (int)(longSize * (double)size.Height / size.Width)));
}
return(new Size((int)(longSize * (double)size.Width / size.Height), longSize));
}
}
