public ImageMatBlackWhite ToImageBlackWhite(int threshold)
{
var bools = new bool[Width * Height];
for (int i = 0; i < data.Length; i++)
{
bools[i] = data[i].ToPixelGray() > threshold ? true : false;
}
ImageMatBlackWhite result = new ImageMatBlackWhite(bools, Width, Height, false);
return(result);
}
public HoughTransform(ImageMatBlackWhite pic, int scale)
{
this.image = pic;
this.scale = scale;
/*(x,y) => Hough-Space (θ,d)
* θ：the angle between x-axis and the line which passing through (x,y)
* d : the distance from origin to the line which passing through (x,y)
*
*
* so, mathematically,
* d = xcosθ + ysinθ
* by The auxiliary Angle formula(辅助角公式),
* max(d) = sqrt(x²+y²)
* so d:[-sqrt(x²+y²),sqrt(x²+y²)]
*/
double maxr = Math.Sqrt((pic.Width * pic.Width + pic.Height * pic.Height));
//we need to create a array two times big because d:[-sqrt(x²+y²),sqrt(x²+y²)]
maxd = (int)Math.Ceiling(maxr) + 1;
hough_space = new HoughPixel[maxd * 2, scale + 1];
for (int i = 0; i < maxd * 2; i++)
{
for (int j = 0; j < scale + 1; j++)
{
hough_space[i, j].minx = int.MaxValue;
hough_space[i, j].miny = int.MaxValue;
hough_space[i, j].maxx = int.MinValue;
hough_space[i, j].maxy = int.MinValue;
}
}
/*
* maxd*2 because d:[-sqrt(x²+y²),sqrt(x²+y²)] => d:[-maxd,maxd]
* scale+1 because 0<=i<=scale
*/
//θ=π/scale*x,so save the tmpθ to accelerate calcaltion /
ttheta = Math.PI / scale;
}
