public List <Rectangle> DetectLetters(Image <Bgr, Byte> img)
{
var hash = img.GetHashCode();
List <Rectangle> rects = new List <Rectangle>();
var imgGray = img.Convert <Gray, Byte>();
var imgSobel = imgGray.Sobel(1, 0, 3).Convert <Gray, Byte>();
var imgRes = new Image <Gray, byte>(imgSobel.Size);
CvInvoke.Threshold(imgSobel, imgRes, 160, 255, ThresholdType.Binary | ThresholdType.Otsu);
var element = CvInvoke.GetStructuringElement(ElementShape.Rectangle, new Size(2, 2), new Point(-1, -1));
CvInvoke.Dilate(imgRes, imgRes, element, new Point(0, 0), 1, BorderType.Default, new MCvScalar(0));
CvInvoke.Erode(imgRes, imgRes, element, new Point(0, 0), 12, BorderType.Default, new MCvScalar(0));
using (Mat hierachy = new Mat())
using (VectorOfVectorOfPoint contours = new VectorOfVectorOfPoint())
{
CvInvoke.FindContours(imgRes, contours, hierachy, RetrType.Tree, ChainApproxMethod.ChainApproxNone);
for (int i = 0; i < contours.Size; i++)
{
Rectangle rectangle = CvInvoke.BoundingRectangle(contours[i]);
var area = rectangle.Width * rectangle.Height;
if (area > 1400 && rectangle.Width < img.Width * 0.7 && rectangle.Width > rectangle.Height * 1.5)
{
rects.Add(rectangle);
}
}
}
return(rects);
}
/// <summary>
/// Find the bounding rectangle for the specific array of points
/// </summary>
/// <param name="points">The collection of points</param>
/// <returns>The bounding rectangle for the array of points</returns>
public static Rectangle BoundingRectangle(PointF[] points)
{
using (VectorOfPointF ptVec = new VectorOfPointF(points))
return(CvInvoke.BoundingRectangle(ptVec));
}
