Getting better color lithophanes with better swatches
When I came up with the first version of color lithophanes my swatches were pretty simple. Basically there were 4 colors, I printed a swatch that had all the possible combinations there could be in 5 layers, and then took a photo and read in the rgb values. These were the values I would match the pixels in the image to get the closest color match.
For many color lithophanes this match worked fine, but there were images that looked really bad though. The issue is this swatch doesn’t take into account the effect of the thickness of the lithophane on top. So for blacks instead of letting the lithophane thickness control level of grey the program matches black with the “darkest” color in the swatch, leading to blue “black” cats.
It was clear I needed many more color values. I redesigned the swatches so I could have a white swatch on top that had thickness between 0.05 and 5.0mm. I then printed color swatches with various thicknesses and took photos of all the combinations.
I did have to be very careful with how I did the photography as each photo needed to have the exact same settings. I couldn’t have the camera adjusting lighting between shots. I also needed a very stable setup so the photos were from the exact same distance.
To get all the possible color combinations it took hundreds of photos, each with one hundred color samples to read. I was able to write a python program that automated reading in the rgb values (somewhat) painlessly. In the end for the EPAX filament I started with there were over 15,000 color values read.
Fortunately I don’t have to compare each color pixel with 15,000 values, just the values at the lithopane thickness for that color level, so more like several hundred. Still heavy computing though.
This process is a ton more work but I am happy with the results I’m getting. While I’m not ready to state a firm timeline for the beta I do have a functioning web app, though not ready for the public. Below is the first print using it and I’m pretty happy with it (check out the whiskers! and ignore the cat hair…)
Stay tuned!