private string reconhecerCaptcha(Image img)
{
Bitmap imagem = new Bitmap(img);
imagem = imagem.Clone(new Rectangle(0, 0, img.Width, img.Height), System.Drawing.Imaging.PixelFormat.Format24bppRgb);
Erosion erosion = new Erosion();
Dilatation dilatation = new Dilatation();
Invert inverter = new Invert();
ColorFiltering cor = new ColorFiltering();
cor.Blue = new AForge.IntRange(200, 255);
cor.Red = new AForge.IntRange(200, 255);
cor.Green = new AForge.IntRange(200, 255);
Opening open = new Opening();
BlobsFiltering bc = new BlobsFiltering();
Closing close = new Closing();
GaussianSharpen gs = new GaussianSharpen();
ContrastCorrection cc = new ContrastCorrection();
bc.MinHeight = 10;
FiltersSequence seq = new FiltersSequence(gs, inverter, open, inverter, bc, inverter, open, cc, cor, bc, inverter);
pictureBox.Image = seq.Apply(imagem);
string reconhecido = OCR((Bitmap)pictureBox.Image);
return reconhecido;
}