You could use something like this to resize it:
Dim bm_source As New Bitmap(picturebox.Image)
Dim bm_dest As New Bitmap(150, 200)
Dim gr_dest As Graphics = Graphics.FromImage(bm_dest)
gr_dest.DrawImage(bm_source, 0, 0, bm_dest.Width + 1, bm_dest.Height + 1)
picturebox.Image = bm_dest
You could also save the bitmap immediately to file of course without assigning it back to the picturebox.
Good luck!