How to clip a rectangle from a tiff?

Question

I have a Winforms Gui in C# that allows a user to draw a rectangle on a display of a tiff and save the position, height, width etc. Basically, what I want to do is take the saved position, height and width of the rectangle and clip that area into a sep. bitmap that can then be passed to sep. method that will just OCR the new clip of the bitmap only. What is the best way to do this?

Answer 1

Use Graphics.DrawImage() to copy the selection portion of the source image. You'll need the overload that takes a source and a destination Rectangle. Create the Graphics instance from Graphics.FromImage() on a new bitmap that has the same size as the rectangle.

    public static Bitmap CropImage(Image source, Rectangle crop) {
        var bmp = new Bitmap(crop.Width, crop.Height);
        using (var gr = Graphics.FromImage(bmp)) {
            gr.DrawImage(source, new Rectangle(0, 0, bmp.Width, bmp.Height), crop, GraphicsUnit.Pixel);
        }
        return bmp;
    }

Answer 2

Use Bitmap.Clone() to create a copy of the cropped region.

public Bitmap ClipBitmap(Bitmap src, Rectangle crop)
{
  return src.Clone(crop, src.PixelFormat);
}