private static DataRectangle <double> Blur(DataRectangle <double> values, int maxRadius)
{
return(values.Transform((value, point) =>
{
var valuesInArea = new List <double>();
for (var x = -maxRadius; x <= maxRadius; x++)
{
for (var y = -maxRadius; y <= maxRadius; y++)
{
var newPoint = new Point(point.X + x, point.Y + y);
if ((newPoint.X < 0) || (newPoint.Y < 0) ||
(newPoint.X >= values.Width) || (newPoint.Y >= values.Height))
{
continue;
}
valuesInArea.Add(values[newPoint.X, newPoint.Y]);
}
}
return valuesInArea.Average();
}));
}
private static IEnumerable <int> GetBarLengthsFromBarcodeSlice(DataRectangle <bool> barcodeDetails, int sliceY)
{
if ((sliceY < 0) || (sliceY >= barcodeDetails.Height))
{
throw new ArgumentOutOfRangeException(nameof(sliceY));
}
// Take the horizontal slice of the data
var values = new List <bool>();
for (var x = 0; x < barcodeDetails.Width; x++)
{
values.Add(barcodeDetails[x, sliceY]);
}
// Split the slice into bars - we only care about how long each segment is when they
// alternate, not whether they're dark bars or light bars
var segments = new List <Tuple <bool, int> >();
foreach (var value in values)
{
if ((segments.Count == 0) || (segments[^ 1].Item1 != value))
/// <summary>
/// This will return values in the range 0-255 (inclusive)
/// </summary>
// Based on http://stackoverflow.com/a/4748383/3813189
public static DataRectangle <double> GetGreyscale(this Bitmap image)
{
var values = new double[image.Width, image.Height];
var data = image.LockBits(
new Rectangle(0, 0, image.Width, image.Height),
ImageLockMode.ReadOnly,
PixelFormat.Format24bppRgb
);
try
{
var pixelData = new Byte[data.Stride];
for (var lineIndex = 0; lineIndex < data.Height; lineIndex++)
{
Marshal.Copy(
source: data.Scan0 + (lineIndex * data.Stride),
destination: pixelData,
startIndex: 0,
length: data.Stride
);
for (var pixelOffset = 0; pixelOffset < data.Width; pixelOffset++)
{
// Note: PixelFormat.Format24bppRgb means the data is stored in memory as BGR
const int PixelWidth = 3;
var r = pixelData[pixelOffset * PixelWidth + 2];
var g = pixelData[pixelOffset * PixelWidth + 1];
var b = pixelData[pixelOffset * PixelWidth];
values[pixelOffset, lineIndex] = (0.2989 * r) + (0.5870 * g) + (0.1140 * b);
}
}
}
finally
{
image.UnlockBits(data);
}
return(DataRectangle.For(values));
}
private static string?TryToReadBarcodeValueFromSingleLine(DataRectangle <bool> barcodeDetails, int sliceY)
{
if ((sliceY < 0) || (sliceY >= barcodeDetails.Height))
{
throw new ArgumentOutOfRangeException(nameof(sliceY));
}
var lengths = GetBarLengthsFromBarcodeSlice(barcodeDetails, sliceY).ToArray();
if (lengths.Length < 57)
{
// As explained, we'd like 60 bars (which would include the final guard region) but we
// can still make an attempt with 57 (but no fewer)
// - There will often be another section of blank content after the barcode that we ignore
// - If we don't want to validate the final guard region then we can work with a barcode
// image where some of the end is cut off, so long as the data for the 12 digits is
// there (this will be the case where there are only 57 lengths)
return(null);
}
var offset = 0;
var extractedNumericValues = new List <int>();
for (var i = 0; i < 14; i++)
{
if (i == 0)
{
// This should be the first guard region and it should be a pattern of three single-
// width bars
offset += 3;
}
else if (i == 7)
{
// This should be the guard region in the middle of the barcode and it should be a
// pattern of five single-width bars
offset += 5;
}
else
{
var value = TryToGetValueForLengths(
lengths[offset],
lengths[offset + 1],
lengths[offset + 2],
lengths[offset + 3]
);
if (value is null)
{
return(null);
}
extractedNumericValues.Add(value.Value);
offset += 4;
}
}
// Calculate what the checksum should be based upon the first 11 numbers and ensure that
// the 12th matches it
if (extractedNumericValues.Last() != CalculateChecksum(extractedNumericValues.Take(11)))
{
return(null);
}
return(string.Join("", extractedNumericValues));
}
