Not all screens and monitors are built to the same standards of color depth and accuracy, and your eyes also have their limits. Now, you can find out just how well you (and your devices) can tell colors apart, potentially for bragging rights.
Software developer Keith Cirkel has created the ‘Your ΔE(OK) JND?’ website, allowing you to determine the Delta-E (ΔE) of your Just Noticeable Difference (JND), using the Oklab color space supported in modern browsers. In other words, you get a score based on your ability to tell one color apart from the other color, with about 40 rounds of tests. You just have to find and click/tap the line between the two colors on the screen.
Even though this is primarily a test of the human eye, with most people earning a score around 0.02 in the Oklab color space, your equipment also matters. If you have a phone with a low-end display panel, or a budget gaming monitor with terrible color calibration, you’ll probably receive worse scores. Bumping up the brightness could also help you get the best results. The more decimal points, the better.
I earned a score of 0.0051 on my iPhone 15 with its OLED screen, and a score of 0.0058 on my 2024 MacBook Pro with its Liquid Retina XDR display. Other folks here at How-To Geek also noticed different results across different devices. Your final score can be easily sent to others with a customized URL, as evidence of your superior or inferior vision range.
Cirkel made the website while working on a CSS color minifier, where it was important to find out how many decimal points could be realistically removed from color values. He explained in a blog post, “Is a color like oklch(0.659432 0.304219 234.75238) needlessly precise? Spoiler alert: yes. I contend that you almost never need more than 3 decimal places. For oklch and oklab that’s a safe ceiling, and for their less-than-ok variants (lab & lch) you can get away with even less. Writing more is just wasting bytes.”
The blog post (linked below) goes into far more detail about the science behind the test, including how the Delta-E is mapped across different color spaces, and how web browsers calculate color values. Crikel also noted that the website produces higher Just Noticeable Difference scores than real-world scenarios—outside of gamified tests like this, most people are not staring closely at their screen to check color matching.
Source: Keith Cirkel
