topic IM95 Libcamera - Configure manual gain/exposure in i.MX Processors

IM95 Libcamera - Configure manual gain/exposure

rolin99 — Mon, 08 Dec 2025 16:41:59 GMT

Hi,

I am currently trying to configure the manual gain/exposure for `os08a20` model cameras with IMX95. We have configured the gain and exposure to be 1.0 analog gain and 3000US for exposure with the following:

req->controls().set(libcamera::controls::AeEnable, false);
req->controls().set(libcamera::controls::ExposureTime, 3000);
req->controls().set(libcamera::controls::AnalogueGain, 1.0);

However, it appears that the Libcamera debug logs are indicating gain/exposure values being set via NXP NEO AGC computed values. Can you advise on how to properly configure manual exposure and analog gain values via Libcamera API?

Re: IM95 Libcamera - Configure manual gain/exposure

rolin99 — Mon, 08 Dec 2025 17:46:59 GMT

Re: IM95 Libcamera - Configure manual gain/exposure

rolin99 — Mon, 08 Dec 2025 19:09:48 GMT

For reference, this is the Libcamera version I'm using: https://github.com/nxp-imx/libcamera

Re: IM95 Libcamera - Configure manual gain/exposure

joanxie — Tue, 09 Dec 2025 05:53:28 GMT

try to use command as below to set

cam --camera X --stream width=${W},height=${H},pixelformat=YUYV --capture=1000 --display=HDMI-A-1 --script script_gain_exposure.yaml

Re: IM95 Libcamera - Configure manual gain/exposure

rolin99 — Tue, 09 Dec 2025 14:55:15 GMT

HI joanxie,

I think I need to be able to programmatically change the gain/exposure via Libcamera API rather than using the `cam` tool.

Re: IM95 Libcamera - Configure manual gain/exposure

joanxie — Wed, 10 Dec 2025 05:49:31 GMT

cam also used libcamera, refer to the linux user guide, Libcamera comes with the cam test application that uses the native libcamera API

Re: IM95 Libcamera - Configure manual gain/exposure

rolin99 — Wed, 10 Dec 2025 15:23:48 GMT

Hi Joanxie,

I used the cam tool to stream, however, I am seeing some inconsistent results in the libcamera logs. The logs are showing the following configs being applied:

[0:17:10.346165015] [2328] DEBUG NxpNeoAlgoAgc agc.cpp:193 Set exposure to 712

[0:17:09.504320639] [2321] DEBUG NxpNeoAlgoGoc goc.cpp:185 [xferFunc] linearGain: 12.92, linearThreshold: 0.0031308, nonLinearGain: 1.055, nonLinearOffset: 0.0521327, gammaInverse: 0.416667

[0:17:07.826928461] [2321] DEBUG NxpNeoAlgoDrc drc.cpp:654 global GAIN=256

[0:17:10.346186099] [2328] DEBUG NxpNeoAlgoAgc agc.cpp:201 Set gain to 1

These don't match up with the config in the YAML file. The full logs also included in this msg.

Re: IM95 Libcamera - Configure manual gain/exposure

rolin99 — Wed, 10 Dec 2025 15:31:08 GMT

[0:32:37.475564258] [3313] DEBUG NxpNeoAlgoAgc agc.cpp:415 Divided up exposure time, analogue gain and digital gain are 16554.43us, 15.5 and 2.4224

Re: IM95 Libcamera - Configure manual gain/exposure

joanxie — Mon, 15 Dec 2025 06:55:35 GMT

I tested os08a20 with my imx95 evk board, the command is

my script is

frames:
  - 0:
      AeEnable: false
      AnalogueGain: 1.0000000
      ExposureTime: 10000
  - 10:
      AeEnable: false
      AnalogueGain: 5.0000000
      ExposureTime: 60000
  - 20:
      AeEnable: false
      AnalogueGain: 1.0000000
      ExposureTime: 10000
  - 30:
      AeEnable: false
      AnalogueGain: 5.0000000
      ExposureTime: 60000
  - 40:
      AeEnable: false
      AnalogueGain: 1.0000000
      ExposureTime: 10000
  - 50:
      AeEnable: false
      AnalogueGain: 5.0000000
      ExposureTime: 60000
  - 100:
      AeEnable: false
      AnalogueGain: 1.0000000
      ExposureTime: 10000
 
the log file is

 

the result is the same as settings, but I found it has 4 frame delay, internal team still investigate this