' See http://www.vb-helper.com/howto_net_image_resize.html for the original code
Dim PicBoxHeight As Integer
Dim PicBoxWidth As Integer
Dim ImageHeight As Integer
Dim ImageWidth As Integer
Dim TempImage As Image
Dim scale_factor As Single
 
PictureBox1.SizeMode = PictureBoxSizeMode.Normal
' Get control size
PicBoxHeight = PictureBox1.Height
PicBoxWidth = PictureBox1.Width
 ' Load the image. Change Image.FromFile() to match your code
TempImage = Image.FromFile("D:\Download\Image00b.jpg")
' Get image size
ImageHeight = TempImage.Height
ImageWidth = TempImage.Width
' Calculate scale_factor
scale_factor = 1.0 ' No scaling by default i.e. image fits in the Box
' 1) Height
If ImageHeight > PicBoxHeight Then
  ' Reduce height first
  scale_factor = CSng(PicBoxHeight / ImageHeight)
End If
' 2) Width. Notice, we do know now how much we have to scale down the height
' and the scale_factor affects width too
If (ImageWidth * scale_factor) > PicBoxWidth Then
  ' Scaled width exceeds Box's width, recalculate scale_factor
  scale_factor = CSng(PicBoxWidth / ImageWidth)
End If
 
' Move image to control for resizing
PictureBox1.Image = TempImage
 
' Get the source bitmap.
Dim bm_source As New Bitmap(PictureBox1.Image)
' Make a bitmap for the result.
Dim bm_dest As New Bitmap( _
    CInt(bm_source.Width * scale_factor), _
    CInt(bm_source.Height * scale_factor))
' Make a Graphics object for the result Bitmap.
Dim gr_dest As Graphics = Graphics.FromImage(bm_dest)
' Copy the source image into the destination bitmap.
gr_dest.DrawImage(bm_source, 0, 0, _
    bm_dest.Width + 1, _
    bm_dest.Height + 1)
' Display the result.
PictureBox1.Image = bm_dest