image getting blurred when enlarging picture box

Question

I am developing an application for image processing. To zoom the image, I enlarge PictureBox. But after enlarging I get below image as result.

But I want result like below image

Here is my Code :

      picturebox1.Size = new Size((int)(height * zoomfactor), (int) 
      (width* zoomfactor));
      this.picturebox1.Refresh();

Answer 1

The PictureBox by itself will always create a nice and smooth version.

To create the effect you want you need to draw zoomed versions yourself. In doing this you need to set the

 Graphics.InterpolationMode = InterpolationMode.NearestNeighbor;

Then no blurring will happen..

Example:

private void trackBar1_Scroll(object sender, EventArgs e)
{
    Bitmap bmp = (Bitmap)pictureBox1.Image;
    Size sz = bmp.Size;
    Bitmap zoomed = (Bitmap)pictureBox2.Image;
    if (zoomed != null) zoomed.Dispose();

    float zoom = (float)(trackBar1.Value / 4f + 1);
    zoomed = new Bitmap((int)(sz.Width * zoom), (int)(sz.Height * zoom));

    using (Graphics g = Graphics.FromImage(zoomed))
    {
      if (cbx_interpol.Checked) g.InterpolationMode = InterpolationMode.NearestNeighbor;
      g.DrawImage(bmp, new Rectangle( Point.Empty, zoomed.Size) );
    }
    pictureBox2.Image = zoomed;
}

Of course you need to avoid setting the PBox to Sizemode Zoom or Stretch!

Answer 2

It could be the image type that is the issue. If you expand the image then you are reducing the compression quality. Maybe this link might help

image Scaling of picture box