I’m a Solarized fan. In Vim, I used to manually switch between the dark and the light modes depending on the lighting conditions. Two weeks ago, while browsing usevim‘s feed, I found Holy Light — “a plugin for Macs that changes the background variable based on the amount of ambient light recorded by Mac’s light sensor.”

To use Holy Light, you have to set a threshold for the ambient light level. When measured value is above that threshold, the light background is used; when it’s below the threshold, the background is dark. Access to the light sensor data is provided by the holylight-checker binary bundled with the plugin.

What caught my attention is that the measured values are in the range of millions1 (of unknown units). This suggests an incredible fidelity! I decided to investigate. I recorded the light level every five seconds during a day at the office. Here are my results2.

As expected, measurements aren’t precise. You can safely discard last five digits of that million. Or even six: