After the photoshoot, I created a new PS document using the bright photo as a base. I created a mask on the scene, so that if necessary, I could duplicate the mask to any layer that showed up too brightly outside of the scene. (See http://planetphotoshop.com/creating-and-duplicating-a-layer-mask.html for an excellent tutorial on duplicating layer masks.)
I then used Photoshop’s File / Scripts / “Load Files into Stack” feature to load all of the photos of one particular color into individual layers in a new (and huge) document. For each such document, I turned the various photos on and off until I found the ambience I wanted and then duplicated those layers to the main document.
(Note that the trick to combining these layers so that they all show up as a light painting is in setting all of their Blending Modes to Lighten. You can leave the Opacity at 100% for all layers, and yet the light paintings in each individual photo will be visible in the composite image. As shown above, I set the Opacity at 60% for only one layer, the one highlighting the elf on the right, since it was spotlighted in white and needed to be toned down to blend in with the rest of the blue layers. Also as shown above, I used layer groups to organize the many images that go into a single composite light painting.)
I did the same (“Load Files into Stack” documents) for the various light drawings, which included eighth notes, quarter notes, half notes, whole notes, staff lines, treble clefs, bass clefs, and words. These were extremely tricky; although I am a musician and do write music, I had to not only draw the musical symbols in the tiny confines between the physical piano and the camera’s angle of view, I had to draw them backwards so that they look correct to the viewer.
In the end, the musical notation that looked the best overall included only one quarter note, a bunch of eighth notes, and a treble clef. It would have been nice to include more variety, but it was very hard to judge where to draw them all so that they didn’t overlap. Note that except for two minor position tweaks (the treble clef and the barred eighth notes on the right), I did not Photoshop the musical elements in the final image; I drew them where they stand. It amazes me how well they line up.
I also added the “HoHo” so that Santa could sing.
The final image coloring includes, unfortunately, only the blue elements plus a couple of white elements. I discovered, much to my dismay after a couple of hours of shooting, that each color collection was slightly ajar from each other. I had tried to be wicked careful in not moving the camera at all, but it apparently happened anyway. When I tried to stack different colors, things did not line up, and no amount of aligning layers could get them in line. Plus, Santa fell further onto the keyboard and popped up slightly out of his cup without me knowing it, and the lady elf on the left did something similar, and there was therefore no way to fix those deviations after the fact.