Why when i save from the pictureBox1.Image the image to the hard disk the size is smaller then the pictureBox1 size ?

The pictureBox1 size is: 1381,494

The image inaise is stretch.

Then im doing:

 private void trackBar2_Scroll(object sender, EventArgs e)
        {
            LoadPictureAt(trackBar2.Value, sender);
            label1.Text = "Image Number: "+ trackBar2.Value.ToString();
            pictureBox1.Refresh();
            counter++;
            pictureBox1.Image.Save(@"d:\CloudColorsFiltered\" + "AnimatedImageColors" + counter.ToString("D6"), System.Drawing.Imaging.ImageFormat.Gif);
        }

This is the two lines i just added now:

counter++;
pictureBox1.Image.Save(@"d:\CloudColorsFiltered\" + "AnimatedImageColors" + counter.ToString("D6"), System.Drawing.Imaging.ImageFormat.Gif);

The image the gif on my hard disk is 512,512 size

Why its saving the gif so small and not as the size of the pictureBox1 ?