static BooleanMatrix FilterRelativeContrast(DoubleMatrix contrast, BlockMap blocks)
{
var sortedContrast = new List <double>();
foreach (var block in contrast.Size.Iterate())
{
sortedContrast.Add(contrast[block]);
}
sortedContrast.Sort();
sortedContrast.Reverse();
int pixelsPerBlock = blocks.Pixels.Area / blocks.Primary.Blocks.Area;
int sampleCount = Math.Min(sortedContrast.Count, Parameters.RelativeContrastSample / pixelsPerBlock);
int consideredBlocks = Math.Max(Doubles.RoundToInt(sampleCount * Parameters.RelativeContrastPercentile), 1);
double averageContrast = 0;
for (int i = 0; i < consideredBlocks; ++i)
{
averageContrast += sortedContrast[i];
}
averageContrast /= consideredBlocks;
var limit = averageContrast * Parameters.MinRelativeContrast;
var result = new BooleanMatrix(blocks.Primary.Blocks);
foreach (var block in blocks.Primary.Blocks.Iterate())
{
if (contrast[block] < limit)
{
result[block] = true;
}
}
// https://sourceafis.machinezoo.com/transparency/relative-contrast-mask
FingerprintTransparency.Current.Log("relative-contrast-mask", result);
return(result);
}
static byte[,] ComputeOrientationMap(double[,] image, bool[,] mask, BlockMap blocks)
{
PointF[,] accumulated = ComputePixelwiseOrientation(image, mask, blocks);
PointF[,] byBlock = AverageBlockOrientations(accumulated, blocks, mask);
PointF[,] smooth = SmoothOutOrientationMap(byBlock, mask);
return(ConvertOrientationVectorsToAngles(smooth, mask));
}
static bool[,] Binarize(double[,] input, double[,] baseline, bool[,] mask, BlockMap blocks)
{
var size = Point.SizeOf(input);
var binarized = size.Allocate <bool>();
for (int blockY = 0; blockY < blocks.AllBlocks.Height; ++blockY)
{
for (int blockX = 0; blockX < blocks.AllBlocks.Width; ++blockX)
{
if (mask[blockY, blockX])
{
Rectangle rect = blocks.BlockAreas[blockY, blockX];
for (int y = rect.Bottom; y < rect.Top; ++y)
{
for (int x = rect.Left; x < rect.Right; ++x)
{
if (input[y, x] - baseline[y, x] > 0)
{
binarized[y, x] = true;
}
}
}
}
}
}
return(binarized);
}
public static MutableTemplate Extract(DoubleMatrix raw, double dpi)
{
var template = new MutableTemplate();
// https://sourceafis.machinezoo.com/transparency/decoded-image
FingerprintTransparency.Current.Log("decoded-image", raw);
if (Math.Abs(dpi - 500) > Parameters.DpiTolerance)
{
raw = ScaleImage(raw, dpi);
}
// https://sourceafis.machinezoo.com/transparency/scaled-image
FingerprintTransparency.Current.Log("scaled-image", raw);
template.Size = raw.Size;
var blocks = new BlockMap(raw.Width, raw.Height, Parameters.BlockSize);
// https://sourceafis.machinezoo.com/transparency/blocks
FingerprintTransparency.Current.Log("blocks", blocks);
var histogram = Histogram(blocks, raw);
var smoothHistogram = SmoothHistogram(blocks, histogram);
var mask = Mask(blocks, histogram);
var equalized = Equalize(blocks, raw, smoothHistogram, mask);
var orientation = OrientationMap(equalized, mask, blocks);
var smoothedLines = OrientedLines(Parameters.ParallelSmoothingResolution, Parameters.ParallelSmoothingRadius, Parameters.ParallelSmoothingStep);
var smoothed = SmoothRidges(equalized, orientation, mask, blocks, 0, smoothedLines);
// https://sourceafis.machinezoo.com/transparency/parallel-smoothing
FingerprintTransparency.Current.Log("parallel-smoothing", smoothed);
var orthogonalLines = OrientedLines(Parameters.OrthogonalSmoothingResolution, Parameters.OrthogonalSmoothingRadius, Parameters.OrthogonalSmoothingStep);
var orthogonal = SmoothRidges(smoothed, orientation, mask, blocks, Math.PI, orthogonalLines);
// https://sourceafis.machinezoo.com/transparency/orthogonal-smoothing
FingerprintTransparency.Current.Log("orthogonal-smoothing", orthogonal);
var binary = Binarize(smoothed, orthogonal, mask, blocks);
var pixelMask = FillBlocks(mask, blocks);
CleanupBinarized(binary, pixelMask);
// https://sourceafis.machinezoo.com/transparency/pixel-mask
FingerprintTransparency.Current.Log("pixel-mask", pixelMask);
var inverted = Invert(binary, pixelMask);
var innerMask = InnerMask(pixelMask);
var ridges = new Skeleton(binary, SkeletonType.Ridges);
var valleys = new Skeleton(inverted, SkeletonType.Valleys);
template.Minutiae = new List <MutableMinutia>();
CollectMinutiae(template.Minutiae, ridges, MinutiaType.Ending);
CollectMinutiae(template.Minutiae, valleys, MinutiaType.Bifurcation);
// https://sourceafis.machinezoo.com/transparency/skeleton-minutiae
FingerprintTransparency.Current.Log("skeleton-minutiae", template);
MaskMinutiae(template.Minutiae, innerMask);
// https://sourceafis.machinezoo.com/transparency/inner-minutiae
FingerprintTransparency.Current.Log("inner-minutiae", template);
RemoveMinutiaClouds(template.Minutiae);
// https://sourceafis.machinezoo.com/transparency/removed-minutia-clouds
FingerprintTransparency.Current.Log("removed-minutia-clouds", template);
template.Minutiae = LimitTemplateSize(template.Minutiae);
// https://sourceafis.machinezoo.com/transparency/top-minutiae
FingerprintTransparency.Current.Log("top-minutiae", template);
return(template);
}
static DoubleMatrix OrientationMap(DoubleMatrix image, BooleanMatrix mask, BlockMap blocks)
{
var accumulated = PixelwiseOrientation(image, mask, blocks);
var byBlock = BlockOrientations(accumulated, blocks, mask);
var smooth = SmoothOrientation(byBlock, mask);
return(OrientationAngles(smooth, mask));
}
public FingerprintTemplate(byte[,] image, int dpi = 500)
{
const int blockSize = 15;
if (dpi != 500)
{
image = ScaleImage(image, dpi);
}
image = InvertInput(image);
var blocks = new BlockMap(new Point(image.GetLength(1), image.GetLength(0)), blockSize);
var histogram = ComputeHistogram(blocks, image);
var smoothHistogram = ComputeSmoothedHistogram(blocks, histogram);
var mask = ComputeMask(blocks, histogram);
double[,] equalized = Equalize(blocks, image, smoothHistogram, mask);
byte[,] orientation = ComputeOrientationMap(equalized, mask, blocks);
double[,] smoothed = SmoothByOrientation(equalized, orientation, mask, blocks, 0, ConstructOrientedLines(step: 1.59));
double[,] orthogonal = SmoothByOrientation(smoothed, orientation, mask, blocks, Angle.PIB,
ConstructOrientedLines(resolution: 11, radius: 4, step: 1.11));
var binary = Binarize(smoothed, orthogonal, mask, blocks);
CleanupBinarized(binary);
BitmapUtils.ShowImage(binary);
var pixelMask = FillBlocks(mask, blocks);
var innerMask = ComputeInnerMask(pixelMask);
var inverted = Invert(binary, pixelMask);
FingerprintSkeleton ridges = new FingerprintSkeleton(binary);
FingerprintSkeleton valleys = new FingerprintSkeleton(inverted);
CollectMinutiae(ridges, FingerprintMinutiaType.Ending);
CollectMinutiae(valleys, FingerprintMinutiaType.Bifurcation);
ApplyMask(innerMask);
RemoveMinutiaClouds();
LimitTemplateSize();
ShuffleMinutiae();
BuildEdgeTable();
}
static bool[,] ComputeMask(BlockMap blocks, int[, ,] histogram)
{
byte[,] contrast = ComputeClippedContrast(blocks, histogram);
var mask = ComputeAbsoluteContrast(contrast);
MergeMask(mask, ComputeRelativeContrast(contrast, blocks));
MergeMask(mask, ApplyVotingFilter(mask, radius: 9, majority: 0.86, borderDist: 7));
MergeMask(mask, FilterBlockErrors(mask));
mask = InvertMask(mask);
MergeMask(mask, FilterBlockErrors(mask));
MergeMask(mask, FilterBlockErrors(mask));
MergeMask(mask, ApplyVotingFilter(mask, radius: 7, borderDist: 4));
return(mask);
}
static bool[,] FillBlocks(bool[,] mask, BlockMap blocks)
{
bool[,] pixelized = blocks.PixelCount.Allocate <bool>();
foreach (var block in blocks.AllBlocks)
{
if (block.Get(mask))
{
foreach (var pixel in blocks.BlockAreas[block])
{
pixel.Set(pixelized, true);
}
}
}
return(pixelized);
}
static BooleanMatrix FillBlocks(BooleanMatrix mask, BlockMap blocks)
{
var pixelized = new BooleanMatrix(blocks.Pixels);
foreach (var block in blocks.Primary.Blocks.Iterate())
{
if (mask[block])
{
foreach (var pixel in blocks.Primary.Block(block).Iterate())
{
pixelized[pixel] = true;
}
}
}
return(pixelized);
}
static BooleanMatrix Mask(BlockMap blocks, HistogramCube histogram)
{
var contrast = ClipContrast(blocks, histogram);
var mask = FilterAbsoluteContrast(contrast);
mask.Merge(FilterRelativeContrast(contrast, blocks));
// https://sourceafis.machinezoo.com/transparency/combined-mask
FingerprintTransparency.Current.Log("combined-mask", mask);
mask.Merge(FilterBlockErrors(mask));
mask.Invert();
mask.Merge(FilterBlockErrors(mask));
mask.Merge(FilterBlockErrors(mask));
mask.Merge(Vote(mask, null, Parameters.MaskVoteRadius, Parameters.MaskVoteMajority, Parameters.MaskVoteBorderDistance));
// https://sourceafis.machinezoo.com/transparency/filtered-mask
FingerprintTransparency.Current.Log("filtered-mask", mask);
return(mask);
}
static int[, ,] ComputeHistogram(BlockMap blocks, byte[,] image)
{
var histogram = new int[blocks.BlockCount.Y, blocks.BlockCount.X, 256];
foreach (var block in blocks.AllBlocks)
{
var area = blocks.BlockAreas[block];
for (int y = area.Bottom; y < area.Top; ++y)
{
for (int x = area.Left; x < area.Right; ++x)
{
++histogram[block.Y, block.X, image[y, x]];
}
}
}
return(histogram);
}
static bool[,] ComputeRelativeContrast(byte[,] contrast, BlockMap blocks)
{
const int sampleSize = 168568;
const double sampleFraction = 0.49;
const double relativeLimit = 0.34;
List <byte> sortedContrast = new List <byte>();
foreach (byte contrastItem in contrast)
{
sortedContrast.Add(contrastItem);
}
sortedContrast.Sort();
sortedContrast.Reverse();
int pixelsPerBlock = blocks.PixelCount.Area / blocks.AllBlocks.TotalArea;
int sampleCount = Math.Min(sortedContrast.Count, sampleSize / pixelsPerBlock);
int consideredBlocks = Math.Max(Convert.ToInt32(sampleCount * sampleFraction), 1);
int averageContrast = 0;
for (int i = 0; i < consideredBlocks; ++i)
{
averageContrast += sortedContrast[i];
}
averageContrast /= consideredBlocks;
byte limit = Convert.ToByte(averageContrast * relativeLimit);
var result = blocks.BlockCount.Allocate <bool>();
for (int y = 0; y < blocks.BlockCount.Y; ++y)
{
for (int x = 0; x < blocks.BlockCount.X; ++x)
{
if (contrast[y, x] < limit)
{
result[y, x] = true;
}
}
}
return(result);
}
static byte[,] ComputeClippedContrast(BlockMap blocks, int[, ,] histogram)
{
const double clipFraction = 0.08;
byte[,] result = new byte[blocks.BlockCount.Y, blocks.BlockCount.X];
foreach (var block in blocks.AllBlocks)
{
int area = 0;
for (int i = 0; i < 256; ++i)
{
area += histogram[block.Y, block.X, i];
}
int clipLimit = Convert.ToInt32(area * clipFraction);
int accumulator = 0;
int lowerBound = 255;
for (int i = 0; i < 256; ++i)
{
accumulator += histogram[block.Y, block.X, i];
if (accumulator > clipLimit)
{
lowerBound = i;
break;
}
}
accumulator = 0;
int upperBound = 0;
for (int i = 255; i >= 0; --i)
{
accumulator += histogram[block.Y, block.X, i];
if (accumulator > clipLimit)
{
upperBound = i;
break;
}
}
result[block.Y, block.X] = (byte)(upperBound - lowerBound);
}
return(result);
}
static HistogramCube Histogram(BlockMap blocks, DoubleMatrix image)
{
var histogram = new HistogramCube(blocks.Primary.Blocks, Parameters.HistogramDepth);
foreach (var block in blocks.Primary.Blocks.Iterate())
{
var area = blocks.Primary.Block(block);
for (int y = area.Top; y < area.Bottom; ++y)
{
for (int x = area.Left; x < area.Right; ++x)
{
int depth = (int)(image[x, y] * histogram.Bins);
histogram.Increment(block, histogram.Constrain(depth));
}
}
}
// https://sourceafis.machinezoo.com/transparency/histogram
FingerprintTransparency.Current.Log("histogram", histogram);
return(histogram);
}
static int[, ,] ComputeSmoothedHistogram(BlockMap blocks, int[, ,] input)
{
var blocksAround = new Point[] { new Point(0, 0), new Point(-1, 0), new Point(0, -1), new Point(-1, -1) };
var output = new int[blocks.CornerCount.Y, blocks.CornerCount.X, 256];
foreach (var corner in blocks.AllCorners)
{
foreach (Point relative in blocksAround)
{
var block = corner + relative;
if (blocks.AllBlocks.Contains(block))
{
for (int i = 0; i < 256; ++i)
{
output[corner.Y, corner.X, i] += input[block.Y, block.X, i];
}
}
}
}
return(output);
}
static PointF[,] AverageBlockOrientations(PointF[,] orientation, BlockMap blocks, bool[,] mask)
{
PointF[,] sums = new PointF[blocks.BlockCount.Y, blocks.BlockCount.X];
foreach (var block in blocks.AllBlocks)
{
if (block.Get(mask))
{
PointF sum = new PointF();
Rectangle area = blocks.BlockAreas[block];
for (int y = area.Bottom; y < area.Top; ++y)
{
for (int x = area.Left; x < area.Right; ++x)
{
sum += orientation[y, x];
}
}
sums[block.Y, block.X] = sum;
}
}
return(sums);
}
static PointF[,] ComputePixelwiseOrientation(double[,] input, bool[,] mask, BlockMap blocks)
{
List <List <ConsideredOrientation> > neighbors = GetTestedOrientations();
PointF[,] orientation = new PointF[input.GetLength(0), input.GetLength(1)];
for (int blockY = 0; blockY < blocks.BlockCount.Y; ++blockY)
{
Range validMaskRange = GetMaskLineRange(mask, blockY);
if (validMaskRange.Length > 0)
{
Range validXRange = new Range(blocks.BlockAreas[blockY, validMaskRange.Begin].Left,
blocks.BlockAreas[blockY, validMaskRange.End - 1].Right);
for (int y = blocks.BlockAreas[blockY, 0].Bottom; y < blocks.BlockAreas[blockY, 0].Top; ++y)
{
foreach (ConsideredOrientation neighbor in neighbors[y % neighbors.Count])
{
int radius = Math.Max(Math.Abs(neighbor.CheckLocation.X), Math.Abs(neighbor.CheckLocation.Y));
if (y - radius >= 0 && y + radius < input.GetLength(0))
{
Range xRange = new Range(Math.Max(radius, validXRange.Begin),
Math.Min(input.GetLength(1) - radius, validXRange.End));
for (int x = xRange.Begin; x < xRange.End; ++x)
{
double before = input[y - neighbor.CheckLocation.Y, x - neighbor.CheckLocation.X];
double at = input[y, x];
double after = input[y + neighbor.CheckLocation.Y, x + neighbor.CheckLocation.X];
double strength = at - Math.Max(before, after);
if (strength > 0)
{
orientation[y, x] = orientation[y, x] + strength * neighbor.OrientationVector;
}
}
}
}
}
}
}
return(orientation);
}
static DoublePointMatrix BlockOrientations(DoublePointMatrix orientation, BlockMap blocks, BooleanMatrix mask)
{
var sums = new DoublePointMatrix(blocks.Primary.Blocks);
foreach (var block in blocks.Primary.Blocks.Iterate())
{
if (mask[block])
{
var area = blocks.Primary.Block(block);
for (int y = area.Top; y < area.Bottom; ++y)
{
for (int x = area.Left; x < area.Right; ++x)
{
sums.Add(block, orientation[x, y]);
}
}
}
}
// https://sourceafis.machinezoo.com/transparency/block-orientation
FingerprintTransparency.Current.Log("block-orientation", sums);
return(sums);
}
static HistogramCube SmoothHistogram(BlockMap blocks, HistogramCube input)
{
var blocksAround = new IntPoint[] { new IntPoint(0, 0), new IntPoint(-1, 0), new IntPoint(0, -1), new IntPoint(-1, -1) };
var output = new HistogramCube(blocks.Secondary.Blocks, input.Bins);
foreach (var corner in blocks.Secondary.Blocks.Iterate())
{
foreach (var relative in blocksAround)
{
var block = corner + relative;
if (blocks.Primary.Blocks.Contains(block))
{
for (int i = 0; i < input.Bins; ++i)
{
output.Add(corner, i, input[block, i]);
}
}
}
}
// https://sourceafis.machinezoo.com/transparency/smoothed-histogram
FingerprintTransparency.Current.Log("smoothed-histogram", output);
return(output);
}
static DoubleMatrix ClipContrast(BlockMap blocks, HistogramCube histogram)
{
var result = new DoubleMatrix(blocks.Primary.Blocks);
foreach (var block in blocks.Primary.Blocks.Iterate())
{
int volume = histogram.Sum(block);
int clipLimit = Doubles.RoundToInt(volume * Parameters.ClippedContrast);
int accumulator = 0;
int lowerBound = histogram.Bins - 1;
for (int i = 0; i < histogram.Bins; ++i)
{
accumulator += histogram[block, i];
if (accumulator > clipLimit)
{
lowerBound = i;
break;
}
}
accumulator = 0;
int upperBound = 0;
for (int i = histogram.Bins - 1; i >= 0; --i)
{
accumulator += histogram[block, i];
if (accumulator > clipLimit)
{
upperBound = i;
break;
}
}
result[block] = (upperBound - lowerBound) * (1.0 / (histogram.Bins - 1));
}
// https://sourceafis.machinezoo.com/transparency/contrast
FingerprintTransparency.Current.Log("contrast", result);
return(result);
}
static double[,] SmoothByOrientation(double[,] input, byte[,] orientation, bool[,] mask, BlockMap blocks, byte angle, Point[][] lines)
{
double[,] output = new double[input.GetLength(0), input.GetLength(1)];
foreach (var block in blocks.AllBlocks)
{
if (block.Get(mask))
{
Point[] line = lines[Angle.Quantize(Angle.Add(orientation[block.Y, block.X], angle), lines.Length)];
foreach (Point linePoint in line)
{
Rectangle target = blocks.BlockAreas[block];
Rectangle source = target.GetShifted(linePoint);
source.Clip(new Rectangle(blocks.PixelCount));
target = source.GetShifted(-linePoint);
for (int y = target.Bottom; y < target.Top; ++y)
{
for (int x = target.Left; x < target.Right; ++x)
{
output[y, x] += input[y + linePoint.Y, x + linePoint.X];
}
}
}
Rectangle blockArea = blocks.BlockAreas[block];
for (int y = blockArea.Bottom; y < blockArea.Top; ++y)
{
for (int x = blockArea.Left; x < blockArea.Right; ++x)
{
output[y, x] *= 1.0 / line.Length;
}
}
}
}
return(output);
}
static double[,] Equalize(BlockMap blocks, byte[,] image, int[, ,] histogram, bool[,] blockMask)
{
const double maxScaling = 3.99;
const double minScaling = 0.25;
const double rangeMin = -1;
const double rangeMax = 1;
const double rangeSize = rangeMax - rangeMin;
const double widthMax = rangeSize / 256 * maxScaling;
const double widthMin = rangeSize / 256 * minScaling;
var limitedMin = new double[256];
var limitedMax = new double[256];
var toFloatTable = new double[256];
for (int i = 0; i < 256; ++i)
{
limitedMin[i] = Math.Max(i * widthMin + rangeMin, rangeMax - (255 - i) * widthMax);
limitedMax[i] = Math.Min(i * widthMax + rangeMin, rangeMax - (255 - i) * widthMin);
toFloatTable[i] = i / 255;
}
var cornerMapping = new double[blocks.CornerCount.Y, blocks.CornerCount.X, 256];
foreach (var corner in blocks.AllCorners)
{
if (corner.Get(blockMask, false) ||
new Point(corner.X - 1, corner.Y).Get(blockMask, false) ||
new Point(corner.X, corner.Y - 1).Get(blockMask, false) ||
new Point(corner.X - 1, corner.Y - 1).Get(blockMask, false))
{
int area = 0;
for (int i = 0; i < 256; ++i)
{
area += histogram[corner.Y, corner.X, i];
}
double widthWeigth = rangeSize / area;
double top = rangeMin;
for (int i = 0; i < 256; ++i)
{
double width = histogram[corner.Y, corner.X, i] * widthWeigth;
double equalized = top + toFloatTable[i] * width;
top += width;
double limited = equalized;
if (limited < limitedMin[i])
{
limited = limitedMin[i];
}
if (limited > limitedMax[i])
{
limited = limitedMax[i];
}
cornerMapping[corner.Y, corner.X, i] = limited;
}
}
}
var result = new double[blocks.PixelCount.Y, blocks.PixelCount.X];
foreach (var block in blocks.AllBlocks)
{
if (block.Get(blockMask))
{
var area = blocks.BlockAreas[block];
for (int y = area.Bottom; y < area.Top; ++y)
{
for (int x = area.Left; x < area.Right; ++x)
{
byte pixel = image[y, x];
double bottomLeft = cornerMapping[block.Y, block.X, pixel];
double bottomRight = cornerMapping[block.Y, block.X + 1, pixel];
double topLeft = cornerMapping[block.Y + 1, block.X, pixel];
double topRight = cornerMapping[block.Y + 1, block.X + 1, pixel];
var fraction = area.GetFraction(new Point(x, y));
result[y, x] = MathEx.Interpolate(topLeft, topRight, bottomLeft, bottomRight, fraction);
}
}
}
}
return(result);
}
static DoubleMatrix Equalize(BlockMap blocks, DoubleMatrix image, HistogramCube histogram, BooleanMatrix blockMask)
{
const double rangeMin = -1;
const double rangeMax = 1;
const double rangeSize = rangeMax - rangeMin;
double widthMax = rangeSize / histogram.Bins * Parameters.MaxEqualizationScaling;
double widthMin = rangeSize / histogram.Bins * Parameters.MinEqualizationScaling;
var limitedMin = new double[histogram.Bins];
var limitedMax = new double[histogram.Bins];
var dequantized = new double[histogram.Bins];
for (int i = 0; i < histogram.Bins; ++i)
{
limitedMin[i] = Math.Max(i * widthMin + rangeMin, rangeMax - (histogram.Bins - 1 - i) * widthMax);
limitedMax[i] = Math.Min(i * widthMax + rangeMin, rangeMax - (histogram.Bins - 1 - i) * widthMin);
dequantized[i] = i / (double)(histogram.Bins - 1);
}
var mappings = new Dictionary <IntPoint, double[]>();
foreach (var corner in blocks.Secondary.Blocks.Iterate())
{
double[] mapping = new double[histogram.Bins];
mappings[corner] = mapping;
if (blockMask.Get(corner, false) ||
blockMask.Get(corner.X - 1, corner.Y, false) ||
blockMask.Get(corner.X, corner.Y - 1, false) ||
blockMask.Get(corner.X - 1, corner.Y - 1, false))
{
double step = rangeSize / histogram.Sum(corner);
double top = rangeMin;
for (int i = 0; i < histogram.Bins; ++i)
{
double band = histogram[corner, i] * step;
double equalized = top + dequantized[i] * band;
top += band;
if (equalized < limitedMin[i])
{
equalized = limitedMin[i];
}
if (equalized > limitedMax[i])
{
equalized = limitedMax[i];
}
mapping[i] = equalized;
}
}
}
var result = new DoubleMatrix(blocks.Pixels);
foreach (var block in blocks.Primary.Blocks.Iterate())
{
var area = blocks.Primary.Block(block);
if (blockMask[block])
{
var topleft = mappings[block];
var topright = mappings[new IntPoint(block.X + 1, block.Y)];
var bottomleft = mappings[new IntPoint(block.X, block.Y + 1)];
var bottomright = mappings[new IntPoint(block.X + 1, block.Y + 1)];
for (int y = area.Top; y < area.Bottom; ++y)
{
for (int x = area.Left; x < area.Right; ++x)
{
int depth = histogram.Constrain((int)(image[x, y] * histogram.Bins));
double rx = (x - area.X + 0.5) / area.Width;
double ry = (y - area.Y + 0.5) / area.Height;
result[x, y] = Doubles.Interpolate(bottomleft[depth], bottomright[depth], topleft[depth], topright[depth], rx, ry);
}
}
}
else
{
for (int y = area.Top; y < area.Bottom; ++y)
{
for (int x = area.Left; x < area.Right; ++x)
{
result[x, y] = -1;
}
}
}
}
// https://sourceafis.machinezoo.com/transparency/equalized-image
FingerprintTransparency.Current.Log("equalized-image", result);
return(result);
}
static DoublePointMatrix PixelwiseOrientation(DoubleMatrix input, BooleanMatrix mask, BlockMap blocks)
{
var neighbors = PlanOrientations();
var orientation = new DoublePointMatrix(input.Size);
for (int blockY = 0; blockY < blocks.Primary.Blocks.Y; ++blockY)
{
var maskRange = MaskRange(mask, blockY);
if (maskRange.Length > 0)
{
var validXRange = new IntRange(
blocks.Primary.Block(maskRange.Start, blockY).Left,
blocks.Primary.Block(maskRange.End - 1, blockY).Right);
for (int y = blocks.Primary.Block(0, blockY).Top; y < blocks.Primary.Block(0, blockY).Bottom; ++y)
{
foreach (var neighbor in neighbors[y % neighbors.Length])
{
int radius = Math.Max(Math.Abs(neighbor.Offset.X), Math.Abs(neighbor.Offset.Y));
if (y - radius >= 0 && y + radius < input.Height)
{
var xRange = new IntRange(Math.Max(radius, validXRange.Start), Math.Min(input.Width - radius, validXRange.End));
for (int x = xRange.Start; x < xRange.End; ++x)
{
double before = input[x - neighbor.Offset.X, y - neighbor.Offset.Y];
double at = input[x, y];
double after = input[x + neighbor.Offset.X, y + neighbor.Offset.Y];
double strength = at - Math.Max(before, after);
if (strength > 0)
{
orientation.Add(x, y, strength * neighbor.Orientation);
}
}
}
}
}
}
}
// https://sourceafis.machinezoo.com/transparency/pixelwise-orientation
FingerprintTransparency.Current.Log("pixelwise-orientation", orientation);
return(orientation);
}
static BooleanMatrix Binarize(DoubleMatrix input, DoubleMatrix baseline, BooleanMatrix mask, BlockMap blocks)
{
var size = input.Size;
var binarized = new BooleanMatrix(size);
foreach (var block in blocks.Primary.Blocks.Iterate())
{
if (mask[block])
{
var rect = blocks.Primary.Block(block);
for (int y = rect.Top; y < rect.Bottom; ++y)
{
for (int x = rect.Left; x < rect.Right; ++x)
{
if (input[x, y] - baseline[x, y] > 0)
{
binarized[x, y] = true;
}
}
}
}
}
// https://sourceafis.machinezoo.com/transparency/binarized-image
FingerprintTransparency.Current.Log("binarized-image", binarized);
return(binarized);
}
static DoubleMatrix SmoothRidges(DoubleMatrix input, DoubleMatrix orientation, BooleanMatrix mask, BlockMap blocks, double angle, IntPoint[][] lines)
{
var output = new DoubleMatrix(input.Size);
foreach (var block in blocks.Primary.Blocks.Iterate())
{
if (mask[block])
{
var line = lines[DoubleAngle.Quantize(DoubleAngle.Add(orientation[block], angle), lines.Length)];
foreach (var linePoint in line)
{
var target = blocks.Primary.Block(block);
var source = target.Move(linePoint).Intersect(new IntRect(blocks.Pixels));
target = source.Move(-linePoint);
for (int y = target.Top; y < target.Bottom; ++y)
{
for (int x = target.Left; x < target.Right; ++x)
{
output.Add(x, y, input[x + linePoint.X, y + linePoint.Y]);
}
}
}
var blockArea = blocks.Primary.Block(block);
for (int y = blockArea.Top; y < blockArea.Bottom; ++y)
{
for (int x = blockArea.Left; x < blockArea.Right; ++x)
{
output.Multiply(x, y, 1.0 / line.Length);
}
}
}
}
return(output);
}