public static unsafe Bitmap Sobel(Bitmap source)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
var pixelFormat = source.PixelFormat;
var bpp = (byte)Image.GetPixelFormatSize(pixelFormat) / 8;
var hasAlpha = bpp > 3;
if (hasAlpha)
{
source = GrayscaleRgba(source);
}
else
{
source = GrayscaleRgb(source);
}
var target = new Bitmap(source.Width, source.Height, source.PixelFormat);
var imageBox = new Rectangle(0, 0, source.Width, source.Height);
var sourceData = source.LockBits(imageBox, ImageLockMode.ReadOnly, pixelFormat);
try
{
var targetData = target.LockBits(imageBox, ImageLockMode.WriteOnly, pixelFormat);
try
{
var s0 = (byte *)sourceData.Scan0;
var t0 = (byte *)targetData.Scan0;
var s = sourceData.Stride;
for (var y = 0; y < source.Height; y++)
{
var yn = Math.Max(0, y - 1);
var ym = Math.Min(source.Height - 1, y + 1);
var ybn = yn * bpp;
var yb = y * bpp;
var ybm = ym * bpp;
var rn = s0 + yn * s;
var r = s0 + y * s;
var rm = s0 + ym * s;
var tr = t0 + y * s;
for (var x = 0; x < source.Width; x++)
{
var xn = Math.Max(0, x - 1);
var xm = Math.Min(source.Width - 1, x + 1);
var xbn = xn * bpp;
var xb = x * bpp;
var xbm = xm * bpp;
var dx = rn[xbn] * -1 + rn[xbm] + r[xbn] * -2 + r[xbm] * 2 + rm[xbn] * -1 + rm[xbm];
var dy = rn[xbn] + rn[xb] * 2 + rn[xbm] + rm[xbn] * -1 + rm[xb] * -2 + rm[xbm] * -1;
var mag = Math.Sqrt(dx * dx + dy * dy);
if (mag > byte.MaxValue)
{
tr[xb] = byte.MaxValue;
tr[xb + 1] = byte.MaxValue;
tr[xb + 2] = byte.MaxValue;
}
else if (mag < 0)
{
tr[xb] = 0;
tr[xb + 1] = 0;
tr[xb + 2] = 0;
}
else
{
var c = (byte)mag;
tr[xb] = c;
tr[xb + 1] = c;
tr[xb + 2] = c;
}
}
}
if (bpp > 3)
{
Raw.FillAlpha(targetData);
}
}
finally
{
target.UnlockBits(targetData);
}
}
finally
{
source.UnlockBits(sourceData);
source.Dispose();
}
return(target);
}
public static unsafe Bitmap Buckets(Bitmap source)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
var pixelFormat = source.PixelFormat;
var bpp = (byte)Image.GetPixelFormatSize(pixelFormat) / 8;
var hasAlpha = bpp > 3;
var target = new Bitmap(source.Width, source.Height, source.PixelFormat);
var imageBox = new Rectangle(0, 0, source.Width, source.Height);
var sourceData = source.LockBits(imageBox, ImageLockMode.ReadOnly, pixelFormat);
try
{
var targetData = target.LockBits(imageBox, ImageLockMode.WriteOnly, pixelFormat);
try
{
var s0 = (byte *)sourceData.Scan0;
var t0 = (byte *)targetData.Scan0;
var s = sourceData.Stride;
for (var y = 0; y < source.Height; y++)
{
var srow = s0 + y * s;
var trow = t0 + y * s;
for (var x = 0; x < source.Width; x++)
{
var p = x * bpp;
var b = srow[p];
var g = srow[p + 1];
var r = srow[p + 2];
var a = hasAlpha ? srow[p + 3] : byte.MaxValue;
var v = Color.FromArgb(a, r, g, b).ToColorBucket();
var c = v.ToColorValue();
trow[p] = c;
trow[p + 1] = c;
trow[p + 2] = c;
}
}
if (bpp > 3)
{
Raw.FillAlpha(targetData);
}
}
finally
{
target.UnlockBits(targetData);
}
}
finally
{
source.UnlockBits(sourceData);
}
return(target);
}
