watermak su file gif

[SPEED78]

salve ragazzi secondo voi è possibile fare il watermark con uan scritta su una foto gif? :master:

[SPEED78]

io utilizzo questo codice che funziona benissimo su file jpg :

rivate Sub Button1_ServerClick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.ServerClick
        Dim foto As System.Drawing.Image

        foto = System.Drawing.Image.FromStream(File1.PostedFile.InputStream)
        Dim fotodamodificare As System.Drawing.Graphics
        fotodamodificare = fotodamodificare.FromImage(foto)
        ' Scelgo la font e le dimensioni della scritta
        Dim drawFont As Font
        Dim Pennello As Brush
        drawFont = New Font("Verdana", 16, FontStyle.Bold)
        Pennello = New SolidBrush(Color.FromArgb(200, 255, 255, 90))

        Dim drawPoint As New PointF(0.5F, 0.5F)
        fotodamodificare.DrawString("LBJSHOP", drawFont, Pennello, drawPoint)
        Dim mystream As New System.IO.MemoryStream



        foto.Save(mystream, System.Drawing.Imaging.ImageFormat.Jpeg)
        Dim fotomodificata As System.Drawing.Image
        fotomodificata = fotomodificata.FromStream(mystream)
        fotomodificata.Save(Server.MapPath("public/result.jpg"))
        fotodamodificare.Dispose()

        Response.Write("ciao")
    End Sub

sui file gif mi da questo errore:



A Graphics object cannot be created from an image that has an indexed pixel format.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Exception: A Graphics object cannot be created from an image that has an indexed pixel format.

Source Error:


Line 31: foto = System.Drawing.Image.FromStream(File1.PostedFile.I nputStream)
Line 32: Dim fotodamodificare As System.Drawing.Graphics
Line 33: fotodamodificare = fotodamodificare.FromImage(foto)
Line 34: ' Scelgo la font e le dimensioni della scritta
Line 35: Dim drawFont As Font