The Issue:

People occasionally dye their hair a different color. This process is a bit time-consuming, and it’s not always immediately clear what the results will be.

Although it’s possible for a person to edit a digital photo to preview a new hair color, this type of simulation lacks the immersive three-dimensional quality that would be required to really get a full impression.

Proposal:

Fortunately, advances in computer-controlled digital image projection have made it possible for colored lighting to be applied in a high resolution fashion: it is now possible to take an object (e.g., a person’s hair) and project a colored light onto only the hair and not the rest of the scene.

We’ll take advantage of this to make a “realistic” 3d hair dye simulation that doesn’t involve any digital images: it will “overwrite” the user’s real hair with a simulated dye result, just by using colored lights.

This is a two step process, shown in Figure 1: in step 1, a reflective dark paint is applied to the user’s hair: this will provide a “baseline” neutral hair color that the lights can then add on top of (note that without bleach, hair dyes can typically only make hair darker, while lights can only make something lighter).

In step 2, colored light is projected onto the user’s dark-gray-painted hair. This should simulate the bleached and/or dyed hair in a convincing fashion.

PROS: Should theoretically work!

CONS: This system might have a hard time competing economically with the much less labor-intensive “just let an A.I. edit the video of your hair in real time” version of this system.

Originally published 2024-06-17.