public static Bitmap Threshold(Bitmap original)
{
int width = original.Width;
int height = original.Height;
Bitmap bmp = new Bitmap(width, height);
using (Graphics g = Graphics.FromImage(bmp))
{
ImageAttributes threshold = new ImageAttributes();
threshold.SetThreshold(0.92f);
//attributes.SetThreshold(0.08f);
g.DrawImage(original, new Rectangle(0, 0, width, height),
0, 0, width, height, GraphicsUnit.Pixel, threshold);
ImageAttributes invert = new ImageAttributes();
ColorMap[] map = new ColorMap[2];
map[0] = new ColorMap();
map[0].OldColor = Color.Black;
map[0].NewColor = Color.White;
map[1] = new ColorMap();
map[1].OldColor = Color.White;
map[1].NewColor = Color.Black;
invert.SetRemapTable(map);
g.DrawImage(bmp, new Rectangle(0, 0, width, height),
0, 0, width, height, GraphicsUnit.Pixel, invert);
}
return bmp;
}
