/// <summary> Compresses a bitmap using TrigradCompression. </summary>
/// <param name="bitmap"> The input bitmap.</param>
/// <param name="options"> TrigradOptions specifying how the image will be compressed.</param>
public static TrigradCompressed CompressBitmap(Bitmap bitmap, TrigradOptions options)
{
TrigradCompressed compressed = new TrigradCompressed { Height = bitmap.Height, Width = bitmap.Width };
List<Point> samplePoints = new List<Point>();
samplePoints.Add(new Point(0, 0));
samplePoints.Add(new Point(bitmap.Width - 1, 0));
samplePoints.Add(new Point(0, bitmap.Height - 1));
samplePoints.Add(new Point(bitmap.Width - 1, bitmap.Height - 1));
double baseChance = 1d / ((double)(bitmap.Width * bitmap.Height) / options.SampleCount / 8);
for (int x = 0; x < bitmap.Width; x++)
{
for (int y = 0; y < bitmap.Height; y++)
{
double chance = ((options.FrequencyTable != null) ? options.FrequencyTable.Table[x, y] : 1d) * baseChance;
if (options.Random.NextDouble() < chance)
{
samplePoints.Add(new Point(x, y));
}
}
}
foreach (var sample in samplePoints)
{
List<Color> averageColors = new List<Color>();
for (int x = sample.X - options.SampleRadius; x < sample.X + options.SampleRadius + 1; x++)
{
for (int y = sample.Y - options.SampleRadius; y < sample.Y + options.SampleRadius + 1; y++)
{
if (y >= 0 && y < bitmap.Height && x >= 0 && x < bitmap.Width)
{
averageColors.Add(bitmap.GetPixel(x, y));
}
}
}
byte R = (byte)averageColors.Average(c => c.R);
byte G = (byte)averageColors.Average(c => c.G);
byte B = (byte)averageColors.Average(c => c.B);
compressed.SampleTable[sample] = Color.FromArgb(R, G, B);
}
return compressed;
}
/// <summary> Decompresses a trigrad compressed bitmap. </summary>
/// <param name="compressionData"> The TrigradCompressed data.</param>
/// <param name="colorGrader"> The color grader that will be used to fill the output bitmap.</param>
/// <param name="debug"> Bool specifying whether a debug output will be produced.</param>
public static TrigradDecompressed DecompressBitmap(TrigradCompressed compressionData, IGrader colorGrader = null,bool debug = false)
{
if (colorGrader == null)
colorGrader = new BarycentricGrader();
TrigradDecompressed decompressed = new TrigradDecompressed(compressionData.Width, compressionData.Height);
//build the triangle mesh
decompressed.Mesh = buildMesh(compressionData.SampleTable);
Parallel.ForEach(decompressed.Mesh.Triangles, triangle =>
{
var vU = triangle.GetVertex(0);
var vV = triangle.GetVertex(1);
var vW = triangle.GetVertex(2);
//find sample points of triangle
Color cU = compressionData.SampleTable[vU.Point()];
Color cV = compressionData.SampleTable[vV.Point()];
Color cW = compressionData.SampleTable[vW.Point()];
//rasterize triangle to find points to fill
var points = TriangleRasterization.PointsInTriangle(vU.Point(), vV.Point(), vW.Point());
foreach (var point in points)
{
var coords = Barycentric.GetCoordinates(point, vU, vV, vW);
Color gradedColor = colorGrader.Grade(cU, cV, cW, coords.U, coords.V, coords.W, point.X, point.Y);
lock (decompressed.Output)
decompressed.Output.SetPixel(point.X, point.Y, gradedColor);
if(debug)
lock (decompressed.DebugOutput)
decompressed.DebugOutput.SetPixel(point.X, point.Y, Color.FromArgb((byte)(coords.U * 255), (byte)(coords.V * 255), (byte)(coords.W * 255)));
}
});
return decompressed;
}
