public Color[] GenerateKMean(int colorsCount,
PaletteOptions options = null,
ColorDistanceType distanceType = ColorDistanceType.Default)
{
options = options ?? PaletteOptions.GetDefault();
var kMeans = new List<LabColor>();
for (var i = 0; i < colorsCount; i++)
{
var lab = LabColor.GetRandom();
while (!lab.IsValidRgb())
{
lab = LabColor.GetRandom();
}
kMeans.Add(lab);
}
var colorSamples = GenerateColorSamples(options);
// Steps
var steps = options.Quality;
var samplesCount = colorSamples.Count;
var samplesClosest = new int?[samplesCount];
while (steps-- > 0)
{
// kMeans -> Samples Closest
for (var i = 0; i < samplesCount; i++)
{
var lab = colorSamples[i];
var minDistance = double.MaxValue;
for (var j = 0; j < kMeans.Count; j++)
{
var kMean = kMeans[j];
var distance = GetColorDistance(lab, kMean, distanceType);
if (distance < minDistance)
{
minDistance = distance;
samplesClosest[i] = j;
}
}
}
// Samples -> kMeans
var freeColorSamples = colorSamples
.Select((lab) => (LabColor)lab.Clone()) // todo do I really need clone each item?
.ToList();
for (var j = 0; j < kMeans.Count; j++)
{
var count = 0;
var candidateKMean = new LabColor();
for (var i = 0; i < colorSamples.Count; i++)
{
if (samplesClosest[i] == j)
{
count++;
var color = colorSamples[i];
candidateKMean.L += color.L;
candidateKMean.A += color.A;
candidateKMean.B += color.B;
}
}
if (count != 0)
{
candidateKMean.L /= count;
candidateKMean.A /= count;
candidateKMean.B /= count;
}
if (count != 0 &&
candidateKMean.IsValidRgb() &&
options.ValidateColor(candidateKMean))
{
kMeans[j] = candidateKMean;
}
else
{
// The candidate kMean is out of the boundaries of the color space, or unfound.
if (freeColorSamples.Count > 0)
{
// We just search for the closest FREE color of the candidate kMean
var minDistance = double.MaxValue;
var closest = -1;
for (var i = 0; i < freeColorSamples.Count; i++)
{
var distance = GetColorDistance(freeColorSamples[i], candidateKMean, distanceType);
if (distance < minDistance)
{
minDistance = distance;
closest = i;
}
}
kMeans[j] = colorSamples[closest];
}
else
{
// Then we just search for the closest color of the candidate kMean
var minDistance = double.MaxValue;
var closest = -1;
for (var i = 0; i < colorSamples.Count; i++)
{
var distance = GetColorDistance(colorSamples[i], candidateKMean, distanceType);
if (distance < minDistance)
{
minDistance = distance;
closest = i;
}
}
kMeans[j] = colorSamples[closest];
}
}
var baseColor = kMeans[j];
freeColorSamples = freeColorSamples
.Where((lab) => !lab.Equals(baseColor))
.ToList();
}
}
return kMeans.Select((lab) => lab.ToRgb()).ToArray();
}
public Color[] GenerateForce(int colorsCount,
PaletteOptions options = null,
ColorDistanceType distanceType = ColorDistanceType.Default)
{
var random = new Random();
var colors = new LabColor[colorsCount];
options = options ?? PaletteOptions.GetDefault();
// Init
for (var i = 0; i < colorsCount; i++)
{
// Find a valid Lab color
var color = LabColor.GetRandom();
while (color.IsValidRgb() || options.ValidateColor(color))
{
color = LabColor.GetRandom();
}
colors[i] = color;
}
// Force vector: repulsion
var repulsion = 100;
var speed = 100;
var steps = options.Quality * 20;
var vectors = new LabVector[colorsCount];
while (steps-- > 0)
{
// Init
for (var i = 0; i < colors.Length; i++)
{
vectors[i] = new LabVector();
}
// Compute Force
for (var i = 0; i < colors.Length; i++)
{
var colorA = colors[i];
for (var j = 0; j < i; j++)
{
var colorB = colors[j];
// repulsion force
var dl = colorA.L - colorB.L;
var da = colorA.A - colorB.A;
var db = colorA.B - colorB.B;
var d = GetColorDistance(colorA, colorB, distanceType);
if (d > 0)
{
var force = repulsion / Math.Pow(d, 2);
vectors[i].dL += dl * force / d;
vectors[i].dA += da * force / d;
vectors[i].dB += db * force / d;
vectors[j].dL -= dl * force / d;
vectors[j].dA -= da * force / d;
vectors[j].dB -= db * force / d;
}
else
{
// Jitter
vectors[j].dL += 2 - 4 * random.NextDouble();
vectors[j].dA += 2 - 4 * random.NextDouble();
vectors[j].dB += 2 - 4 * random.NextDouble();
}
}
}
// Apply Force
for (var i = 0; i < colors.Length; i++)
{
var color = colors[i];
var displacement = speed * vectors[i].Magnitude; ;
if (displacement > 0)
{
var ratio = speed * Math.Min(0.1, displacement) / displacement;
var l = color.L + vectors[i].dL * ratio;
var a = color.A + vectors[i].dA * ratio;
var b = color.B + vectors[i].dB * ratio;
var candidateLab = new LabColor(l, a, b);
if (candidateLab.IsValidRgb() && options.ValidateColor(candidateLab))
{
colors[i] = candidateLab;
}
}
}
}
return colors.Select((lab) => lab.ToRgb()).ToArray();
}
