I am new to this, but have written code to detect an object from an image and then apply background and foreground masks, It works great if there is only one object. I have some images where there are up to 4 different objects. If there are multiple objects my code just selects one and processes that. My code is as follows:
string imgPath = defTempPath + "\" + "picTemp.jpg";// main image to process sketchImg = Cv2.ImRead(imgPath, ImreadModes.AnyColor); if (sketchImg != null) { Mat img = new Mat(sketchImg.Rows, sketchImg.Cols, MatType.CV_8UC1); Cv2.CvtColor(sketchImg, img, ColorConversionCodes.BGR2GRAY); Mat I = new Mat(); Cv2.Threshold(img, I, 50, 255, ThresholdTypes.BinaryInv); //Cv2.Dilate(I, I, Cv2.GetStructuringElement(MorphShapes.Rect, new OpenCvSharp.Size(3, 3))); OpenCvSharp.Point[][] contours; HierarchyIndex[] hierarchyIndexes; Cv2.FindContours(I, out contours, out hierarchyIndexes, RetrievalModes.CComp, ContourApproximationModes.ApproxSimple, null);
int mind = -1;
double marea = 0;
int i = 0;
while (i >= 0)
{
double area = Cv2.ContourArea(contours[i]);
if (area > marea)
{
marea = area;
mind = i;
}
i = hierarchyIndexes[i].Next;
}
if (mind != -1)
{
Mat mask1 = new Mat(img.Rows, img.Cols, sketchImg.Type());
mask1.SetTo(new Scalar(0, 0, 0));
Mat mask2 = new Mat(img.Rows, img.Cols, sketchImg.Type());
mask2.SetTo(new Scalar(0, 0, 0));
var contour = contours[mind];
List<OpenCvSharp.Point> points = contour.ToList();
List<List<OpenCvSharp.Point>> cnt = new List<List<OpenCvSharp.Point>>();
cnt.Add(points);
Cv2.FillPoly(mask1, cnt, new Scalar(255, 255, 255));
i = 0;
while (i >= 0)
{
cnt.Clear();
if (i == mind)
{
i = hierarchyIndexes[i].Next;
}
else
{
contour = contours[i];
points = contour.ToList();
cnt.Add(points);
Cv2.FillPoly(mask2, cnt, new Scalar(255, 255, 255));
i = hierarchyIndexes[i].Next;
}
}
Mat mask = new Mat();
Cv2.Subtract(mask1, mask2, mask);
if (bgImg == null)
{
bgImg = new Mat(sketchImg.Rows, sketchImg.Cols, sketchImg.Type());
bgImg.SetTo(new Scalar(0));
}
if (fgImg == null)
{
fgImg = new Mat(sketchImg.Rows, sketchImg.Cols, sketchImg.Type());
fgImg.SetTo(new Scalar(255));
}
bgImg = bgImg.Resize(sketchImg.Size());
fgImg = fgImg.Resize(sketchImg.Size());
Mat res1 = new Mat(sketchImg.Rows, sketchImg.Cols, sketchImg.Type());
Mat res2 = new Mat(sketchImg.Rows, sketchImg.Cols, sketchImg.Type());
res = new Mat(sketchImg.Rows, sketchImg.Cols, sketchImg.Type());
Cv2.BitwiseAnd(fgImg, mask, res1);
Cv2.BitwiseNot(mask, mask);
Cv2.BitwiseAnd(bgImg, mask, res2);
Cv2.Add(res1, res2, res);
// pictureBox2.SizeMode = PictureBoxSizeMode.Zoom;
pictureBox2.BackgroundImage = new Bitmap(res.ToMemoryStream(), false);
Cv2.ImWrite(defaultOutputPath + "\\op.jpg", res);
here is a sample picture of an image with multiple objects - can not figure out how to add image to post. These are basically line drawings Vector drawings converted to an image.
