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Another Black Light Post

In my last post I said Black Light is working well with Night Shift. It appears that I overlooked something however. With some hardware configurations, the Invert Screen filter of Black Light no longer works except when Night Shift is active. This bug appeared in macOS 10.12.4 so it’s probably linked to some changes that were made in macOS in order to make Night Shift possible. That said, it also affects some models that do not support Night Shift.

If your computer is affected by this and it supports Night Shift, there is a workaround: manually activate Night Shift while Black Light inverts your screen. To minimize the color changes of Night Shift, set it to its lowest color temperature setting in System Preferences. If your Mac does not support Night Shift and you already upgraded to 10.12.4, you are out of luck. Sorry.

I filled a bug report with Apple (31521584) about how some gamma curves are ignored by the system and I’m now waiting a reply. Hopefully this will get fixed in the 10.12.5 update, but this remains uncertain at this time.

Black Light, Night Shift & Flux

Black Light and Night Shift are good friends.

Many users of Black Light also want to use Flux (or f.lux) to tint their screen in warmer colors at night. The problem is that you can’t use both apps at the same time: they each compete to take control of the screen’s gamma curve and the result is a unusable flashing screen alternating between the gamma settings of the two apps.

In yesterday’s 10.12.4 update, macOS Sierra added a Flux-like feature called Night Shift. The good new is that, unlike Flux, Night Shift works well with Black Light.

The mechanism used by Night Shift is different. It does not rely on the gamma curve, which is good as it’s not fighting with Black Light. This also makes it limited in the hardware it supports1. After applying the update, you can check if your computer has the Night Shift tab in Apple Menu > System Preferences > Displays.

There remains only one small caveat: Night Shift combined with the “Invert Screen” filter will tint the screen light blue instead of the expected yellow-orange. Other filters will combine well with Night Shift.

Also of note: Gamma Control works with Night Shift too.


  1. Night Shift is supported by all Macs introduced since 2012, excluding the tower-format Mac Pros. 

Using Black Light to Avoid Image Retention

My iMac slowly started showing signs of image retention (or image persistence) a few months ago. After leaving the screen on for a few hours, I’ll see the imprint of what was left unmoved for too long. It only happens near the edges, and it will fade after some time, but it can be a bit annoying.

My Black Light Preferences

This week I made a little discovery: if I use Black Light to dim the screen by the smallest amount it’ll let me, I get no image retention. Black Light dims the screen by making each pixel color a bit darker, not by dimming the backlight. I suspect changing all the white pixels to a very light gray prevents the liquid crystals from getting stuck.

This is anecdotal: I tested it on my own computer and only for a few days. I can’t be sure it’ll work with other screens that are experiencing image retention. But if your screen has that problem, I think you should give Black Light a try and see for yourself.

Counterparts Lite Update

There’s an update available today for Counterparts Lite. Here’s what’s new in version 1.3.2.

Squashed Bugs

The first has something to do with the currently-edited text not being saved if you close the document window before exiting the text editing mode. I’m pretty sure I saw someone complain about this a while ago in a review in the Mac App Store, but with the review lacking specifics and having no way to interact with the poster I failed to locate the problem.

The second could cause the app to misbehave after editing a key in a .strings file if the key is already present in the document. An alert would appear asking you what to do, and everything went wrong after that. That’s all fixed now.

Auto-update

For customers getting Counterparts Lite directly from the website (as opposed to getting it from the Mac App Store), you will notice that it now includes an auto-update feature.

30-day Free Trial

If you’re not a customer (yet), you can just download the app to start your free trial of 30 days. Visit the Counterparts Lite website to learn more.



  • © 2003–2017 Michel Fortin.