private Tuple <List <int>, List <int> > NeedleSearchArea(IMagickImage image, Gravity gravity)
{
var verticalMargin = image.Height / 4;
var horizontalMargin = image.Height / 3;
switch (gravity)
{
case Gravity.South:
return(Tuple.Create(
LinqExtensions.FromTo(image.Height - verticalMargin, image.Height).AsEnumerable().Reverse().ToList(),
LinqExtensions.FromTo(horizontalMargin, image.Width - horizontalMargin).OrderFromCenter().ToList()
));
case Gravity.North:
return(Tuple.Create(
LinqExtensions.FromTo(0, verticalMargin).ToList(),
LinqExtensions.FromTo(horizontalMargin, image.Width - horizontalMargin).OrderFromCenter().ToList()
));
case Gravity.East:
return(Tuple.Create(
LinqExtensions.FromTo(verticalMargin, image.Height - verticalMargin).OrderFromCenter().ToList(),
LinqExtensions.FromTo(image.Width - horizontalMargin, image.Width).AsEnumerable().Reverse().ToList()
));
case Gravity.West:
return(Tuple.Create(
LinqExtensions.FromTo(verticalMargin, image.Height - verticalMargin).OrderFromCenter().ToList(),
LinqExtensions.FromTo(0, horizontalMargin).ToList()
));
default:
throw new ArgumentException($"Unhandled gravity: {gravity}");
}
}
private List <List <System.Drawing.Color> > ToPixels(IMagickImage image)
{
var pixels = image.GetPixels();
return(LinqExtensions.FromTo(0, image.Height).Select(y => LinqExtensions.FromTo(0, image.Width).Select(x => pixels.GetPixel(x, y).ToColor().ToColor()).ToList()).ToList());
}
private NeedleResult FindHighEntropyStrip(IMagickImage image, Gravity gravity, double NeedleSize, StitchTask task)
{
IProgress <double> progress = task;
var pixels = image.GetPixels();
var t1 = DateTime.UtcNow;
IEnumerable <int> rows = null;
IEnumerable <int> columns = null;
Debug.Assert(image.Height > 1 && image.Width > 1, "Assumes non-empty image");
Debug.Assert(image.Width >= NeedleSize, "Assumes image is at least as big as needle size");
var searchArea = NeedleSearchArea(image, gravity);
rows = searchArea.Item1;
columns = searchArea.Item2;
var minY = rows.Min();
var maxY = rows.Max();
var minX = columns.Min();
var maxX = columns.Max();
var imageDimensions = Tuple.Create(image.Width, image.Height);
List <List <Pixel> > pixelGrid = LinqExtensions.FromTo(minY, maxY).Select(y => LinqExtensions.FromTo(minX, maxX).Select(x => pixels.GetPixel(x, y)).ToList()).ToList();
List <List <float> > brightnessGrid = pixelGrid.Select(xs => xs.Select(p => p.ToColor().ToColor().GetBrightness()).ToList()).ToList();
var gridWidth = maxX - minX;
var gridHeight = maxY - minY;
var bestNeedleStddev = 0.0;
Point bestNeedle = default(Point);
double totalCycles = rows.Count() * columns.Count();
double currentCycle = 0;
Console.WriteLine(brightnessGrid);
foreach (var y in rows)
{
foreach (var x in columns)
{
progress.Report(currentCycle / totalCycles);
currentCycle++;
if (y - minY + NeedleSize >= gridHeight)
{
continue;
}
if (x - minX + NeedleSize >= gridWidth)
{
continue;
}
var count = 0;
var mean = 0.0;
var m2 = 0.0;
double blackCount = 0.0;
for (var x2 = x - minX; x2 < x - minX + NeedleSize; x2++)
{
for (var y2 = y - minY; y2 < y - minY + NeedleSize; y2++)
{
var b = brightnessGrid[y2][x2];
var p = pixelGrid[y2][x2].ToColor();
if (b < 0.08)
{
blackCount++;
}
count++;
var delta = b - mean;
mean = mean + delta / count;
var delta2 = b - mean;
m2 = m2 + delta * delta2;
}
}
var variance = m2 / (count - 1);
var stddev = variance;
//Console.WriteLine("{0}, {1}, {2}", blackCount, NeedleSize * NeedleSize, blackCount / (NeedleSize * NeedleSize));
if (stddev > bestNeedleStddev && blackCount / (NeedleSize * NeedleSize) < 0.5)
{
bestNeedleStddev = stddev;
bestNeedle = new Point(x, y);
}
}
}
return(new NeedleResult()
{
Point = bestNeedle, Entropy = bestNeedleStddev
});
}