4.25 Lighting Changes (More Contrasty?)

I have been making a game in 4.23 and 4.24 with no issues. Yesterday I updated to 4.25, my game is fully dynamically lit (no baking) with only a direct sun-light and a skybox. I never had lighting issues until updating to 4.25.

In the editor and in the “simulate” options I have no issues whatsoever, lighting looks perfect as it always does. But when I play in a new window suddenly the lighting changes almost as if the dynamic range of the scene has changed. The whites become very washed out, the darks look far too light and washed out. The whole scene exposure is significantly increased. As I said it was fine in 4.24.

Why is the lighting different in the editor and SIE than when I open it in a new editor PIE window? I already checked the skybox cube-map and all that, nothing there has changed. So far I’ve tried every setting for lighting during playback (auto exposure/eye adaptation is off). It appears as though a gamma curve is being placed on the whole scene to make it look a lot lighter/brighter/more contrasty.

Does anybody know what this is or how to fix it?

I had this exact thing, and posted here. No repies.

I had to tweak all my lighting.

It’s particulary bad on reflective objects during editing, and metal objects at runtime also have a kind of sparkle.

Interested to hear the outcome…

I figured it out. All fixed now (for my game at least). I went through every single lighting setting and triple checked everything, only to realize that the setting “Auto Exposure Bias” is now set at +1 by default. I’m not sure what the default was before, but you’d think this bias setting wouldn’t matter assuming auto exposure is turned off. Auto exposure is turned off for me, and yet that bias was messing up the lighting still, even with auto exposure (eye adaptation) not working whatsoever or turned on.

Anyways, set that value to 0 and your lighting in-game should look the same as it looked in the editor. Let me know if this works for you.

Project Settings > Engine > Rendering > Default Settings > Auto Exposure Bias.

Ah - thanks! I think you’re right.

Whey on earth would they tweak this? And, yes, why does it make any difference?!

It sounds like the same issue, it’s a bit odd on metals and reflective(s) for me as well. Not necessarily “bad” looking for me, just super over-exposed and a bit washed-out or higher contrast ceiling with the lighting than previous. The weirdest part is just that it differs so vastly from editor view and the simulation view… That in my opinion is when it starts to become a problem, because how can I develop the look of my game if I can’t even see in the editor how things will appear in-game?

I will update this post if and when I find a solution or fix the issue. We need to figure out what is going on.

I did read that they changed how lighting is calculated in Unreal, but that shouldn’t affect runtime vs. live editor differently, whatever changes they made should be standardized between the two. I’ll look into that as well and try to find out if it’s some random setting they added.

I have solved this issue (as far as I’m aware).

Eye adaptation, also known as “auto exposure” in Unreal Engine is turned off in my game… However, the setting “Auto Exposure Bias” as of 4.25 is set to +1 by default. Even if auto exposure is turned off, this setting is still affecting lighting (this might be a glitch), set this number to 0 and your lighting in PIE should appear the same as it does in the editor and simulation.

Auto Exposure Bias can be found here: Project Settings > Engine > Rendering > Default Settings > Auto Exposure Bias.

I can’t say with any certainty, but I think it’s a developer’s error (bug). They did in fact change how eye adaptation works entirely, and update a bunch of stuff. My best guess is that one of the developers forgot some random variable or guard saying “if eye adaptation is turned on then proceed to run this block of code”, so they possibly put the bias in the wrong block of code or forgot a guard perhaps so that it always affects the in-game lighting even when the box is unchecked. Hopefully they’ll update and fix this.