public OrderedDither(uint length)
{
Guard.MustBeGreaterThan(length, 0, nameof(length));
DenseMatrix <uint> ditherMatrix = OrderedDitherFactory.CreateDitherMatrix(length);
// Create a new matrix to run against, that pre-thresholds the values.
// We don't want to adjust the original matrix generation code as that
// creates known, easy to test values.
// https://en.wikipedia.org/wiki/Ordered_dithering#Algorithm
var thresholdMatrix = new DenseMatrix <float>((int)length);
float m2 = length * length;
for (int y = 0; y < length; y++)
{
for (int x = 0; x < length; x++)
{
thresholdMatrix[y, x] = ((ditherMatrix[y, x] + 1) / m2) - .5F;
}
}
this.modulusX = ditherMatrix.Columns;
this.modulusY = ditherMatrix.Rows;
this.thresholdMatrix = thresholdMatrix;
}
/// <summary>
/// Initializes a new instance of the <see cref="OrderedDither"/> class.
/// </summary>
/// <param name="length">The length of the matrix sides</param>
public OrderedDither(uint length)
{
DenseMatrix <uint> ditherMatrix = OrderedDitherFactory.CreateDitherMatrix(length);
this.modulusX = ditherMatrix.Columns;
this.modulusY = ditherMatrix.Rows;
// Adjust the matrix range for 0-255
// TODO: It looks like it's actually possible to dither an image using it's own colors. We should investigate for V2
// https://stackoverflow.com/questions/12422407/monochrome-dithering-in-javascript-bayer-atkinson-floyd-steinberg
int multiplier = 256 / ditherMatrix.Count;
for (int y = 0; y < ditherMatrix.Rows; y++)
{
for (int x = 0; x < ditherMatrix.Columns; x++)
{
ditherMatrix[y, x] = (uint)((ditherMatrix[y, x] + 1) * multiplier) - 1;
}
}
this.thresholdMatrix = ditherMatrix;
}