public static GrayscaleFloatImage Hysteresis(ImageEdges edges, float tMin)
{
var magnitude = edges.Image;
GrayscaleFloatImage dest = new GrayscaleFloatImage(magnitude.Width, magnitude.Height);
float maxBrightness = 256;
var queue = new Queue <Point>(edges.Points);
while (queue.Count > 0)
{
var currentPoint = queue.Dequeue();
var x = currentPoint.X;
var y = currentPoint.Y;
dest[x, y] = maxBrightness;
var xList = Enumerable.Range(x - 1, 3).ToList();
var yList = Enumerable.Range(y - 1, 3).ToList();
var points = xList.SelectMany(i => yList.Select(j => new Point()
{
X = i, Y = j
}))
.Where(p => p.X >= 0 && p.X <= magnitude.Width - 1 &&
p.Y >= 0 && p.Y <= magnitude.Height - 1).ToList();
foreach (var point in points)
{
if (dest[point.X, point.Y] == 0 && magnitude[point.X, point.Y] >= tMin)
{
queue.Enqueue(point);
}
}
}
return(dest);
}
public static ImageEdges NonMaximumSuppression(GrayscaleFloatImage magnitude,
GrayscaleFloatImage directions,
float tMax)
{
ImageEdges dest = new ImageEdges();
dest.Image = new GrayscaleFloatImage(magnitude.Width, magnitude.Height);
dest.Points = new List <Point>();
List <float> allvals = new List <float>();
for (int y = 0; y < magnitude.Height; y++)
{
for (int x = 0; x < magnitude.Width; x++)
{
allvals.Add(magnitude[x, y]);
int direction = (int)directions[x, y];
var pointList = new List <Point>();
var xList = Enumerable.Range(x - 1, 3).ToList();
var yList = Enumerable.Range(y - 1, 3).ToList();
if (direction == 0)
{
pointList = xList.Where(n => n >= 0 && n <= magnitude.Width - 1)
.Select(n => new Point()
{
X = n, Y = y
})
.ToList();
}
else if (direction == 90)
{
pointList = yList.Where(n => n >= 0 && n <= magnitude.Height - 1)
.Select(n => new Point()
{
X = x, Y = n
})
.ToList();
}
else
{
if (direction == 45)
{
xList.Reverse();
}
pointList = xList.Zip(yList, (first, second) => new Point()
{
X = first, Y = second
})
.Where(p => p.X >= 0 && p.X <= magnitude.Width - 1 &&
p.Y >= 0 && p.Y <= magnitude.Height - 1)
.ToList();
}
var values = new List <float>();
foreach (var point in pointList)
{
values.Add(magnitude[point.X, point.Y]);
}
if (values.Max() > magnitude[x, y])
{
dest.Image[x, y] = 0;
}
else
{
dest.Image[x, y] = magnitude[x, y];
if (dest.Image[x, y] >= tMax)
{
dest.Points.Add(new Point()
{
X = x, Y = y
});
}
}
}
}
var a = allvals.Max();
var b = allvals.Min();
return(dest);
}