Hi Giulio,

Thanks for posting in the community.

First of all, I would like to confirm my understanding of your issue.
From your description, I understand that you wants to resize an bitmap and
keep the aspect ratio.
Have I fully understood you? If there is anything I misunderstood, please
feel free to let me know.

Here is a sample, you may take a look.
Private Sub btnScale_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles btnScale.Click
' Get the scale factor.
Dim scale_factor As Single = Single.Parse(txtScale.Text)

' Get the source bitmap.
Dim bm_source As New Bitmap(picSource.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.
picDest.Image = bm_dest
End Sub

You may try the code and let me know the result.

Best regards,

Peter Huang
Microsoft Online Partner Support

Get Secure! - www.microsoft.com/security
This posting is provided "AS IS" with no warranties, and confers no rights.