public static Bitmap Orient_Hough(Bitmap blob)
{
GC.Collect();
Grayscale filter = new Grayscale(0.2125, 0.7154, 0.0721);
Bitmap documentImage = filter.Apply(blob);
//Bitmap documentImage = AForge.Imaging.Image.Clone(blob, PixelFormat.Format16bppGrayScale); //force the jpgs
// create instance of skew checker
DocumentSkewChecker skewChecker = new DocumentSkewChecker();
// get documents skew angle
double angle = skewChecker.GetSkewAngle(documentImage);
// rotate image applying the filter
return RotateImg(blob, (int)-angle, Color.Transparent);
}