Find Starting and Ending Position for an bitmap to Crop

public byte[][] GetRGB(Bitmap bmp)
{
	BitmapData bmp_data = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
	IntPtr ptr = bmp_data.Scan0;
	int num_pixels = bmp.Width * bmp.Height, num_bytes = bmp_data.Stride * bmp.Height, padding = bmp_data.Stride - bmp.Width * 3, i = 0, ct = 1;
	byte[] r = new byte[num_pixels], g = new byte[num_pixels], b = new byte[num_pixels], rgb = new byte[num_bytes];
	System.Runtime.InteropServices.Marshal.Copy(ptr, rgb, 0, num_bytes);
	
	for (int x = 0; x < num_bytes - 3; x += 3)
	{
		if (x == (bmp_data.Stride * ct - padding)) { x += padding; ct++; };
		r[i] = rgb[x]; g[i] = rgb[x + 1]; b[i] = rgb[x + 2]; i++;
	}
	bmp.UnlockBits(bmp_data);
	return new byte[3][] { r, g, b };
}
public Image AutoCrop(Bitmap bmp)
{
	//Get an array containing the R,G,B components of each pixel
	var pixels = GetRGB(bmp);

	int h = bmp.Height - 1, w = bmp.Width, top = 0, bottom = h, left = bmp.Width, right = 0, white = 0;
	int tolerance = 95; // 95%

	bool prev_color = false;
	for (int i = 0; i < pixels[0].Length; i++)
	{
		int x = (i % (w)), y = (int)(Math.Floor((decimal)(i / w))), tol = 255 * tolerance/100; 
		if (pixels[0][i] >= tol && pixels[1][i] >= tol && pixels[2][i] >= tol) { white++; right = (x > right && white == 1) ? x : right; }
		else { left = (x < left && white >= 1) ? x : left; right = (x == w - 1 && white == 0) ? w - 1 : right; white = 0; }
		if (white == w) { top = (y - top < 3) ? y : top; bottom = (prev_color && x == w - 1 && y > top + 1) ? y : bottom; }
		left = (x == 0 && white == 0) ? 0 : left; bottom = (y == h && x == w - 1 && white != w && prev_color) ? h + 1 : bottom;
		if (x == w - 1) { prev_color = (white < w) ? true : false; white = 0; }
	}
	right = (right == 0) ? w : right; left = (left == w) ? 0 : left;

	//Crop the image
	Bitmap bmpCrop = bmp.Clone(new Rectangle(left, top, right - left + 1, bottom - top), bmp.PixelFormat);
	
	return (Bitmap)(bmpCrop);
}

var new_image = AutoCrop(new Bitmap("old.jpg"));
new_image.Save("new.jpg",ImageFormat.Jpeg);