When Kobo announced the Aura One ereader this morning, one question was at the top of everyone's mind:
How the heck did Kobo add a night-reading mode with a red-orange filter?
The thinking behind these filters is that they are better for you to use at night because the blue end of the light spectrum is most likely to keep you up, which is why there are apps for iOS and Android that can do this.
However, the apps use a trick which won't work for E-ink screens; they variously disable the blue light coming out of the RGB pixels on a mobile device's screen (some apps like do a lot more).
The best ereaders on the market have a grayscale screen and a white frontlight, so you would think it would be impossible to add a frontlight which could shift colors.
But Kobo found a solution - one so obvious that I have to wonder why no one else has used it in the seven years since Sony debuted a frontlight on the PRS-700.
A frontlight on an ereader is lit by tiny LEDs around the frame, and the ereader might have any where between 4 to 10 of them. Amazon made a big deal over the Kindle Oasis having ten LEDs (more than any other device) but Kobo found a better use for LEDs.
Kobo added an extra LED which provides a red-orange tint, and then changed the software so that users could adjust the brightness and the tint independently.
Correction: The Aura One has "9 white LEDs and 8 RGB LEDs (with 3 lights in each)".
I shot a couple videos to show it off. The first was in a room lit by sunlight, so it's hard to see the night-reading mode.
The second video was shot in a fairly dim room so that you can see just how strong the red-orange color can get.
I don't know if you can see it in the video, but the red-orange LED appears to be located along the bottom edge of the screen. From what I can tell there is only one, and as a result I can see a noticeable color gradient between the bottom and the top of the screen.
Edit: No, that is just a quirk of the light interactig with the film over the screen.
Then again, I am looking at this screen with a critical eye which is trying to find fault. A regular user might not notice, or care.
What do you think of the night-reading mode?