IMPORTANT!! YOU HAVE TO DOWNLOAD THE IMAGE TO SEE THE DIFFERENCE IF YOU CLICK VIEW IT WILL BE THE SAME, NOT SURE WHAT THE PROBLEM IS. 

tbuckley@ please triage

+derat since this sounds like it might be an adaptive brightness bug on eve. The second screen is darker than the first, which may trigger a backlight change.
+omrilio for launcher as FYI.

I can't repro this at the moment, as my eve's backlight is under manual control. It seems plausible, though. I don't know that there's anything that we can do about it.

I think this is the CABC (Content Adaptive Backlight Control) feature working as intended.

When the content on screen is dark, CABC will make adjust the image shown on screen to lighter image and reduce the screen backlight brightness.

This will lead to longer batter life with a little lower dynamic range on darker screen.

Normally you shouldn't notice this at all but in this case the first screen probably just barely below the threshold and second screen probably just barely pass the threshold of higher CABC level.

For more info, I found that this article does a good job explaining this.
https://www.ecnmag.com/article/2010/04/content-adaptive-lcd-backlight-control

Assign to Eddy to confirm that this is CABC working as intended.

Hmm, I'm not able to reproduce this on an eve device on 63:

Google Chrome	63.0.3239.140 (Official Build) (64-bit)
Platform	10032.86.0 (Official Build) stable-channel eve

I don't see any change in brightness or contrast when switching between my two launcher screens (or the screenshots attached to this bug).

I was not able to reproduce it with these two images on my Eve DVT device either.  However, surely sounds like CABC and is working as intended.  When majority of screen has dark contents, the backlight brightness is reduced to reduce power.  The resulting effect is contrast will be reduced, and colors will look unsaturated.  

A quick way to check if CABC is functional is to set a dark wallpaper or open Chrome in incognito mode, and click on the area with the clock, audio icon, and user image.  As soon as the system menu pops up, and look at the Chrome and Google Play icons on the taskbar.  Without system menu, the icons should have less color saturation, and with system menu, looks normal.  If it is similar to what you see on the app launcher, then it is CABC at work.  

Thanks, Eddy! I can confirm that I'm able to see CABC's effect on this device when I open the system tray (but it's subtle enough that I probably wouldn't notice it unless I'm looking for it).

Marking this issue as WontFix (works as intended).

Please reopen if there are more concerns.