Classic photos of Abe Lincoln seem incredibly detailed, showing tons of wrinkles and cracks in the president’s skin. But much of that “detail” is a flaw of early camera tech, which couldn’t capture a good chunk of the visible light spectrum. Now, a the Time-Travel Rephotography colorization AI shows us what Abe might look like if old cameras were more accurate.
Before the 1900s, camera negatives were blue-sensitive or orthochromatic, meaning that they were more sensitive to light at the top of the visible spectrum than light at the bottom of the visible spectrum. Warm tones, which give skin a soft, luminescent quality through a process called sub-surface scattering, were absent from photography shot before the 1900s, which is why some old portraits look so dang wrinkly.
Time-Travel Rephotography makes up for the shortcomings of early photography through a few interesting tricks. First, the Time-Travel Rephotography team runs a picture (like the portrait of Abe Lincoln) through StyleGan, an that AI that generates portraits of people that do not exist. An AI then uses the full-color “sibling” photo produced by StyleGan to recolor and retouch the black and white source image. After applying some smoothing and sharpening effects, you end up with a “more accurate,” full-color version of your source image.
While AI colorization and the Time-Travel Rephotography method could help us understand what historical figures looked like, the technology is still very flawed. Professional artists who colorize photos spend a lot of time researching their subjects to pick the most accurate colors they possibly can—a task that is currently impossible for AI. Not to mention, image-editing AI tends to distort photos, leaving behind strange artifacts and causing faces to look waxy, melted, or misshapen.
The Time-Travel Rephotography method introduces several opportunities for image distortion, due to the use of “sibling” image references (which alters the shape of the subject’s face), intense smoothing and sharpening algorithms, and of course, the AI’s inability to research its subjects. While Abe Lincoln probably didn’t look as wrinkly as he does in that classic black and white photo, he probably didn’t have the soft, supple, moisturized skin that you see in the AI colorized photo. (Or maybe he did,
Even though it’s a bit flawed, Time-Travel Rephotography is one of the best AI colorization methods available, and it will only grow better with time. Professional colorization may produce better results, but AI colorization is better than nothing and could help people feel more connected with the last 200 years of history.