German Stamp <i>250. Geburtstag Georg Christoph Lichtenberg</i> from <i>Deutsche Bundespost</i>, with partial sheet
Own work  using:  <a href="https://en.wikipedia.org/wiki/Adobe_Photoshop" class="extiw" title="w:Adobe Photoshop">Adobe Photoshop</a>
Own collection, newer scan of the original from a borrowed stamp for scanning