Rotate image in loop using picture box

Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click

        ''Dim BurnNum As Image = pbBurn1.Image
        ''Dim t As Integer = 1
        ''Dim count As Integer = 1
        ''For t = 1 To 3

        ''    If count = 2 Then BurnNum = pbBurn2.Image
        ''    If count = 3 Then BurnNum = pbBurn3.Image

        ' Copy the output bitmap from the source image.
        Dim bm_in As New Bitmap(pbBurn2.Image)  '' Dim bm_in As New Bitmap(BurnNum)

        ' Make an array of points defining the
        ' image's corners.
        Dim wid As Single = bm_in.Width
        Dim hgt As Single = bm_in.Height
        Dim corners As Point() = { _
            New Point(0, 0), _
            New Point(wid, 0), _
            New Point(0, hgt), _
            New Point(wid, hgt)}

        ' Translate to center the bounding box at the origin.
        Dim cx As Single = wid / 2
        Dim cy As Single = hgt / 2
        Dim i As Long
        For i = 0 To 3
            corners(i).X -= cx
            corners(i).Y -= cy
        Next i

        ' Rotate.
        Dim theta As Single = Single.Parse(-45) * PI / 180.0
        Dim sin_theta As Single = Sin(theta)
        Dim cos_theta As Single = Cos(theta)
        Dim X As Single
        Dim Y As Single
        For i = 0 To 3
            X = corners(i).X
            Y = corners(i).Y
            corners(i).X = X * cos_theta + Y * sin_theta
            corners(i).Y = -X * sin_theta + Y * cos_theta
        Next i

        ' Translate so X >= 0 and Y >=0 for all corners.
        Dim xmin As Single = corners(0).X
        Dim ymin As Single = corners(0).Y
        For i = 1 To 3
            If xmin > corners(i).X Then xmin = corners(i).X
            If ymin > corners(i).Y Then ymin = corners(i).Y
        Next i
        For i = 0 To 3
            corners(i).X -= xmin
            corners(i).Y -= ymin
        Next i

        ' Create an output Bitmap and Graphics object.
        Dim bm_out As New Bitmap(CInt(-2 * xmin), CInt(-2 * ymin))
        Dim gr_out As Graphics = Graphics.FromImage(bm_out)

        ' Drop the last corner lest we confuse DrawImage, 
        ' which expects an array of three corners.
        ReDim Preserve corners(2)

        ' Draw the result onto the output Bitmap.
        gr_out.DrawImage(bm_in, corners)

        ' Display the result.
        pbBurn2.Image = bm_out '' Burnnum = bm_out

        ''count = count + 1
        ''Next

    End Sub