Next create an array to hold the rotated pixels and copy the pixels into it. Then use SetBitmapPixels to copy the pixel values into the output PictureBox.

Public Sub RotatePicture(fr_pic As PictureBox, to_pic As _
    PictureBox)
Dim fr_pixels() As RGBTriplet
Dim to_pixels() As RGBTriplet
Dim bits_per_pixel As Integer
Dim fr_wid As Long
Dim fr_hgt As Long
Dim to_wid As Long
Dim to_hgt As Long
Dim X As Integer
Dim Y As Integer

    ' Get the picture's image.
    GetBitmapPixels fr_pic, fr_pixels, bits_per_pixel

    ' Get the picture's size.
    fr_wid = UBound(fr_pixels, 1) + 1
    fr_hgt = UBound(fr_pixels, 2) + 1
    to_wid = fr_hgt
    to_hgt = fr_wid

    ' Size the output picture to fit.
    to_pic.Width = to_pic.Parent.ScaleX(fr_hgt, vbPixels, _
        to_pic.Parent.ScaleMode) + _
        to_pic.Width - to_pic.ScaleWidth
    to_pic.Height = to_pic.Parent.ScaleY(fr_wid, vbPixels, _
        to_pic.Parent.ScaleMode) + _
        to_pic.Height - to_pic.ScaleHeight

    ' Copy the pixels rotated 90 degrees.
    ReDim to_pixels(0 To to_wid - 1, 0 To to_hgt - 1)
    For X = 0 To fr_wid - 1
        For Y = 0 To fr_hgt - 1
            to_pixels(to_wid - Y - 1, X) = fr_pixels(X, Y)
        Next Y
    Next X

    ' Display the result.
    SetBitmapPixels to_pic, bits_per_pixel, to_pixels

    ' Make the image permanent.
    to_pic.Refresh
    to_pic.Picture = to_pic.Image
End Sub