Low Light Boost

Android 15 introduces Low Light Boost, a new auto-exposure mode available to both Camera 2 and the night mode camera extension. Low Light Boost automatically adjusts the brightness of the Preview stream in low-light conditions. This is different from how the night mode camera extension creates still images, because night mode combines a burst of photos to create a single, enhanced image. While night mode works very well for creating a still image, it can't create a continuous stream of frames, but Low Light Boost can. Thus, Low Light Boost enables new camera capabilities, such as the following:

• Providing an enhanced image preview, so users are better able to frame their low-light pictures.
• Scanning QR codes in low light.

If you enable Low Light Boost, it automatically turns on when there's a low light level, and turns off when there's more light.

Apps can record off the Preview stream in low-light conditions to save a brightened video.

You can use Low Light Boost either in Camera2 or through camera extensions. This document covers how to use Low Light Boost with Camera2. You can also use Low Light Boost with the Night Mode camera extension if it is supported by the device.

Check for availability

Before using Low Light Boost, check that it's supported on the device. If it's available, Low Light Boost is one of the exposure modes listed in camera2.CameraCharacteristics.CONTROL_AE_AVAILABLE_MODES. (Low Light Boost is its own auto exposure setting, since other auto exposure settings aren't compatible with the preview brightening performed by Low Light Boost.)

So, to check if Low Light Boost is available, call CameraCharacteristics.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_MODES) and check if the returned modes include ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY:

val characteristics = cameraManager.getCameraCharacteristics(cameraId)
val autoExposureModes =
    characteristics.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_MODES)!!
val lowLightBoostSupported = autoExposureModes.contains(
        CameraMetadata.CONTROL_AE_MODE_ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY)

if (lowLightBoostSupported) {
  // Enable Low Light Boost (next section)
} else {
  // Proceed without Low Light Boost
}

CameraCharacteristics characteristics =
    mCameraManager.getCameraCharacteristics(cameraId);
int[] autoExposureModes =
    characteristics.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_MODES);
boolean lowLightBoostSupported = autoExposureModes.contains(
        CameraMetadata.CONTROL_AE_MODE_ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY);

if (lowLightBoostSupported) {
  // Enable Low Light Boost (next section)
} else {
  // Proceed without Low Light Boost
}

Enable Low Light Boost

To enable Low Light Boost in a Camera2 session, set CaptureRequest.CONTROL_AE_MODE to ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY. After you do so, you'll need to confirm that Low Light Boost was turned on; you can do this by checking the CaptureResult.CONTROL_AE_MODE field. You need to check because Low Light Boost is not compatible with all camera configurations. For example, high-speed recording doesn't support Low Light Boost, due to FPS considerations. If Low Light Boost is not turned on, you may need to change the camera configuration and try again.

val captureRequestBuilder = camera.createCaptureRequest(
  CameraDevice.TEMPLATE_PREVIEW)
if (isLowLightBoostAvailable(cameraId)) {
  captureRequestBuilder.set(
    CaptureRequest.CONTROL_AE_MODE,
    CaptureMetadata.CONTROL_AE_MODE_ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY
  )
}
// other capture request params

session.setRepeatingRequest(
  captureRequestBuilder.build(),
  object : CaptureCallback() {
    @Override
    fun onCaptureCompleted(session: CameraCaptureSession,
        request: CaptureRequest, result: TotalCaptureResult) {
      // verify Low Light Boost AE mode set successfully
      result.get(CaptureResult.CONTROL_AE_MODE) ==
          CaptureMetadata.CONTROL_AE_MODE_ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY
    }
  },
  cameraHandler
)

CaptureRequest.Builder captureRequestBuilder =
  mCamera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
if (isLowLightBoostAvailable(cameraId)) {
  captureRequestBuilder.set(
    CaptureRequest.CONTROL_AE_MODE,
    CameraMetadata.CONTROL_AE_MODE_ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY);
}
// other capture request params

mSession.setRepeatingRequest(
  captureRequestBuilder.build(),
  new CaptureCallback() {
    @Override
    public void onCaptureCompleted(CameraCaptureSession session,
        CaptureRequest request, TotalCaptureResult result) {
      // verify Low Light Boost AE mode set successfully
      result.get(CaptureResult.CONTROL_AE_MODE) ==
          CameraMetadata.CONTROL_AE_MODE_ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY;
    }
  },
  mCameraHandler
);

Monitor Low Light Boost

Low Light Boost brightens the preview stream in low-light conditions, and doesn't have any effect if the environment is already bright enough for normal capture. You can confirm whether Low Light Boost is currently active by checking the CaptureResult.CONTROL_LOW_LIGHT_BOOST_STATE field. If you've turned Low Light Boost on and it's currently active, the field is set to CameraMetadata.CONTROL_LOW_LIGHT_BOOST_STATE_ACTIVE. You might then show a moon icon or some other indication that the preview is being brightened.

session.setRepeatingRequest(
  captureRequestBuilder.build(),
  object : CaptureCallback() {
    @Override
    fun onCaptureCompleted(session: CameraCaptureSession,
        request: CaptureRequest, result: TotalCaptureResult) {
      // check if Low Light Boost is active or inactive
      if (result.get(CaptureResult.CONTROL_LOW_LIGHT_BOOST_STATE) ==
        CaptureMetadata.CONTROL_LOW_LIGHT_BOOST_STATE_ACTIVE) {
        // Low Light Boost state is active
        // Show Moon Icon
      } else {
        // Low Light Boost state is inactive or AE mode is not set
        // to Low Light Boost
        // Hide Moon Icon
      }
    }
  },
  cameraHandler
)

mSession.setRepeatingRequest(
  captureRequestBuilder.build(),
  new CaptureCallback() {
    @Override
    public void onCaptureCompleted(CameraCaptureSession session,
        CaptureRequest request, TotalCaptureResult result) {
      // check if Low Light Boost is active or inactive
      if (result.get(CaptureResult.CONTROL_LOW_LIGHT_BOOST_STATE) ==
        CaptureMetadata.CONTROL_LOW_LIGHT_BOOST_STATE_ACTIVE) {
        // Low Light Boost state is active
        // Show Moon Icon
      } else {
        // Low Light Boost state is inactive or AE mode is not set
        // to Low Light Boost
        // Hide Moon Icon
      }
    }
  },
  mCameraHandler
);