Happy 50th Birthday Paul. These are always fun to do. I learned this technique from Jason Seiler while taking his caricature course at Schoolism.com. The course is pricey but the instruction is priceless. Jason is the nations leading caricature artist (my opinion) and by his inspiration drawing and painting on the computer is becoming real exciting to me. No, it's not a manipulated photography. The following progression of images will give you some idea of the artistic process.
I start with a sketch. I have a Wacom Tablet and Pen which allows me to draw in Photoshop just like I would on paper. With the proper brush settings it acts and looks very much like a pencil. Step two is to establish a mid-tone of value followed by a blocking in of lights and darks. In the next stage I add detail. The program then allows me to add color using the same process. Here is the original photo reference.
To steal Jason's line - "It's funnt because it is true." Caricatures make great gifts. If you know someone having a milestone birthday, getting married, having an anniversary, going away, or you know someone that needs a laugh. I am available. Contact me at firstname.lastname@example.org for pricing.