private static Mat ExtractFace(Mat img, FaceCorners corners)
{
double widthA = Math.Sqrt(Math.Pow(corners.BottomRight.X - corners.BottomLeft.X, 2) + Math.Pow(corners.BottomRight.Y - corners.BottomLeft.Y, 2));
double widthB = Math.Sqrt(Math.Pow(corners.TopRight.X - corners.TopLeft.X, 2) + Math.Pow(corners.TopRight.Y - corners.TopLeft.Y, 2));
double maxWidth = Math.Max(widthA, widthB);
double heightA = Math.Sqrt(Math.Pow(corners.TopRight.X - corners.BottomRight.X, 2) + Math.Pow(corners.TopRight.Y - corners.BottomRight.Y, 2));
double heightB = Math.Sqrt(Math.Pow(corners.TopLeft.X - corners.BottomLeft.X, 2) + Math.Pow(corners.TopLeft.Y - corners.BottomLeft.Y, 2));
double maxHeight = Math.Max(heightA, heightB);
var a = Array.ConvertAll(corners.Points, p => (PointF)p);
var perspectiveTransformationMatrix = CvInvoke.GetPerspectiveTransform(new VectorOfPointF(a), new VectorOfPointF(new[] {
new PointF(0, 0),
new PointF((int)maxWidth - 1, 0),
new PointF((int)maxWidth - 1, (int)maxHeight - 1),
new PointF(0, (int)maxHeight - 1),
}));
var warped = new Mat((int)maxWidth, (int)maxHeight, DepthType.Cv32F, 1);
CvInvoke.WarpPerspective(img, warped, perspectiveTransformationMatrix, new Size((int)maxWidth, (int)maxHeight));
return(warped);
}
private static FaceCorners FindFaceCorners(Mat img, VectorOfKeyPoint trackedFeatures)
{
var rect = CvInvoke.BoundingRectangle(Utils.GetPointsVector(trackedFeatures));
var edges = new Mat();
CvInvoke.Canny(img, edges, 0.1, 99);
var contours = new VectorOfVectorOfPoint();
var hierarchy = new Mat();
var matchedContours = new List <VectorOfPoint>();
CvInvoke.FindContours(edges, contours, hierarchy, RetrType.Tree, ChainApproxMethod.ChainApproxSimple);
for (int i = 0; i < contours.Size; i++)
{
var approx = new Mat();
CvInvoke.ApproxPolyDP(contours[i], approx, 9, true);
var approxMat = new Matrix <double>(approx.Rows, approx.Cols, approx.DataPointer);
double a = Math.Abs(CvInvoke.ContourArea(approx));
if (approxMat.Rows == 4 && Math.Abs(CvInvoke.ContourArea(approx)) > 3000 &&
CvInvoke.IsContourConvex(approx))
{
matchedContours.Add(contours[i]);
}
}
var contoursArray = matchedContours.ToArray().SelectMany(c => c.ToArray()).ToArray();
var contour = matchedContours.FirstOrDefault();
var bbox = CvInvoke.BoundingRectangle(contour);
int minX = contoursArray.Min(p => p.X);
int maxX = contoursArray.Max(p => p.X);
if (!(maxX - minX > 2.9 * bbox.Width))
{
return(new FaceCorners());
}
while (true)
{
bool sutisfied = contoursArray.All(p => p.X > rect.X && p.Y > rect.Y && p.X < (rect.X + rect.Width) && p.Y < (rect.Y + rect.Height));
if (sutisfied)
{
break;
}
if (contoursArray.Any(c => c.X < rect.X))
{
rect.X -= 5;
}
if (contoursArray.Any(c => c.Y < rect.Y))
{
rect.Y -= 5;
}
if (contoursArray.Any(c => c.X > (rect.X + rect.Width)))
{
rect.Width += 5;
}
if (contoursArray.Any(c => c.Y > (rect.Y + rect.Height)))
{
rect.Height += 5;
}
}
var rectPoints = new[]
{
rect.Location,
new PointF(rect.X, rect.Y + rect.Height),
new PointF(rect.X + rect.Width, rect.Y),
new PointF(rect.X + rect.Width, rect.Y + rect.Height)
};
var points2D = Array.ConvertAll(rectPoints, Point.Round);
var corners = new FaceCorners(points2D);
return(corners);
}