public IEnumerable<Segment> Process(ISimpleBitmap input)
{
if (Histogram == null)
{
throw new InvalidOperationException("The histogram must be provided");
}
int[] hx = Histogram.X;
int[] hy = Histogram.Y;
Vector histUpperThreshold = Histogram.Max*0.5f;
// Find seeds for the segmentation:
// All the x and y histogram indices where the value is above the half maximum and have a min distance
const int step = 10;
// x
List<int> ix = GetIndicesAboveThreshold(Histogram.MaxIndex.X, -step, hx, histUpperThreshold.X);
ix.AddRange(GetIndicesAboveThreshold(Histogram.MaxIndex.X + step, step, hx, histUpperThreshold.X));
// y
List<int> iy = GetIndicesAboveThreshold(Histogram.MaxIndex.Y, -step, hy, histUpperThreshold.Y);
iy.AddRange(GetIndicesAboveThreshold(Histogram.MaxIndex.Y + step, step, hy, histUpperThreshold.Y));
// Find the boundaries for the segments defined by the seeds
var segments = new List<Segment>();
foreach (int y0 in iy)
{
foreach (int x0 in ix)
{
var segment = new Segment(0, 0, 0, 0);
segment.Min.X = GetIndexBelowThreshold(x0, -1, hx, ThresholdLuminance.X);
segment.Max.X = GetIndexBelowThreshold(x0, 1, hx, ThresholdLuminance.X);
segment.Min.Y = GetIndexBelowThreshold(y0, -1, hy, ThresholdLuminance.Y);
segment.Max.Y = GetIndexBelowThreshold(y0, 1, hy, ThresholdLuminance.Y);
segments.Add(segment);
}
}
if (segments.Count > 0)
{
// Sort (only pick the largest for now)
Segment foundSegment = segments.OrderByDescending(s => s.DiagonalSq).FirstOrDefault();
// Prevent jittering:
// If the position doesn't change too much over a certain timespan, the last segment is always returned.
// Check for jittering position.
bool isJittering = true;
if ((lastSegment.Min - foundSegment.Min).LengthSq < jitteringAmountThresholdSq)
{
// Check for jittering size
if (System.Math.Abs(foundSegment.DiagonalSq - lastSegment.DiagonalSq) < jitteringAmountThresholdSq)
{
jitteringCount++;
isJittering = false;
}
}
// Freeze or not
if (isJittering)
{
jitteringCount = 0;
}
if (jitteringCount < JitteringCountThreshold)
{
lastSegment = foundSegment;
}
}
return new List<Segment> {lastSegment};
}
public void Reset()
{
jitteringCount = 0;
lastSegment = new Segment(-100, -100, -200, -200);
}
