The code then loops through each pixel in the bitmap and changes the red, green, and blue color components to 225 minus their original value. When it has set each pixel's value, the program sets the picture box's Image property to the bitmap.

Private Sub btnGo_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnGo.Click
    Dim bm As New Bitmap(picCanvas.Image)
    Dim X As Integer
    Dim Y As Integer
    Dim r As Integer
    Dim g As Integer
    Dim b As Integer

    For X = 0 To bm.Width - 1
        For Y = 0 To bm.Height - 1
            r = 255 - bm.GetPixel(X, Y).R
            g = 255 - bm.GetPixel(X, Y).G
            b = 255 - bm.GetPixel(X, Y).B
            bm.SetPixel(X, Y, Color.FromArgb(r, g, b))
        Next Y
    Next X

    picCanvas.Image = bm
End Sub