CameraX AutoFoxus and AutoExposure

[Michael Bramley]

Hi,

I am investigating the functionality of CameraX and am trying to find out

if there is a way to manually control turning these off/on AutoFcus and AutoExposure.

Thank you,

mike

[Eric Ng]

Hi Michael,

Leo answered this in one of our issue trackers:

Currently, ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY is that option drives CameraX to take pictures as soon as possible. It will not trigger/wait any 3A operations/states and immediately request image to camera service.

Hope that helps 

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[Eric Ng]

+Android CameraX Discussion Group 

On Mon, Jan 25, 2021, 11:12 AM Michael Bramley <michael....@gmail.com> wrote:

HI Eric,

What about ImageAnalysis. Our application is only using Preview and ImageAnalyssi.

Thank you,

mike

[tonyt...@google.com]

You may turn off AF/AE by using Camera2CameraControl to set CONTROL_AF_MODE_OFF and CONTROL_AE_MODE_OFF. Note that setting these options will affect both Preview and ImageAnalysis. Means the repeating results will not do metering continuously (e.g. the preview will probably be out of focus when the lens moves). Also all AF/AE related features like CameraControl#startFocusAndMetering will not work.

[Eino-Ville Talvala]

Using AF_MODE_OFF / AE_MODE_OFF will switch exposure and focus to manual control; that's fine if the app wants to set custom exposure/focus values, but if the goal is to just freeze the current values, it may be better to use CONTROL_AE_LOCK.  For focus, locking can be done via CONTROL_AF_TRIGGER.

To view this discussion on the web visit https://groups.google.com/a/android.com/d/msgid/camerax-developers/e256e1f1-007f-472c-b2c1-56e7fed54dadn%40android.com.

[Patrick Liao]

Hi Eino,

Just curious...

What if I set CONTROL_AE_MODE to CONTROL_AE_LOCK and modified CONTROL_AE_ANTIBANDING_MODE and send both capture requests in one shot? Would CameraX (or camera2 in this case) look for the next best settings that adheres the ANTIBANDING_MODE (50Hz/60Hz) then lock AE or would the ANTIBANDING_MODE setting be neglected? This is somewhat crucial for video capture. 

[Eino-Ville Talvala]

Once you set AE_LOCK, all exposure values stop changing immediately; so if you change ANTIBANDING_MODE at the same time, it won't take effect.  If you want to wait for ANTIBANDING_MODE to take effect before you lock exposure, then I'd recommend watching the AE_STATE capture result value; change ANTIBANDING_MODE, wait for AE_STATE to be CONVERGED, and then set AE_LOCK.

To view this discussion on the web visit https://groups.google.com/a/android.com/d/msgid/camerax-developers/e35910db-c4b5-4d88-9a92-d79b49d14628n%40android.com.