I digged deeper into the issue today. After going through the system logs, i can reason with the green tint issue.
The issue
The issue is related to the fingerprint sensor’s (Goodix) backlight. The os doesn’t correctly compensate for the low brightness of the phone with the fingerprint backlight intensity, which causes a certain hue to appear over the screen.
Every time you place a finger on the sensor during enrollment, this sequence fires:
[drm:dsi_panel_set_lhbm_state]: open local hbm
goodix_fp: FP_NOTIFIER_EVENT_UI hbm_status=1, ui_status=1 → FP_UI_READY
This is the display panel briefly boosting brightness locally (Local High Brightness Mode) around the fingerprint area, which is the expected behaviour for under-display optical sensors. This might be the root cause of the green tint.
At low brightness levels, triggering LHBM causes the OLED panel to suddenly spike local brightness/drive current, which in low-brightness conditions can produce a greenish hue due to the OLED subpixel gamma response.
When the screen brightness is low (~0.6 nits range), the abrupt local panel drive increase produces a visible greenish flash. This all can be seen in the system log.
Update- After OS 4.1, someone did mention their screen color change to brown. Meaning they tried to fix the issue in the right place but overshot the values to shift to another hue.
Possible solutions
- The cleanest fix is adding a brightness-aware colour correction table for LHBM. When screen_brightness is below a threshold (say ~0.8 nits), the panel driver should apply a green-channel correction during the HBM spike to compensate for the OLED’s non-linear gamma response at low drive current. This is the same approach other OEMs like Google (Pixel) and Samsung have used to fix identical issues on their under-display sensors.
- Other fix would be to ramp up the LHBM gradually so that the green tint wouldn’t be noticable.
I hope this brings more clarity to the fellow users and the community. This issue lies more on the edge of the os and kernel. As i said in one of my previous posts, this might take some time to resolve due to its explained nature. But definitely, the team is onto it.
PS - I used AI tools to summarize, form and write some sections of this text for clarity and consiceness. This is strictly for NP3 and might reflect misunderstandings too, i do not recommend in anyway that the same would be the reason to the issue for different models as well.
TL;DR: Green tint on NP3 at low brightness is caused by Goodix fingerprint sensor’s LHBM suddenly spiking local brightness, triggering OLED gamma issues (~0.6 nits). No proper compensation from OS. OS 4.1 tried to fix but shifted to brown tint (as per comment(s) for the issue on the community).
