Android 15 引入了低光增强,这是一种新的自动曝光模式,可供 Camera 2 和夜间模式相机扩展使用。“低光提升”功能会在弱光条件下自动调整预览数据流的亮度。这与夜间模式相机扩展程序创建静态图片的方式不同,因为夜间模式会合并多张照片来制作单张增强图片。虽然夜间模式非常适合创建静态图片,但无法创建连续的帧流,但“低光增强”可以。因此,“低光增强”可以启用新的相机功能,例如:
- 提供增强的图片预览,以便用户能够更好地针对弱光环境取景。
- 在光线昏暗的环境下扫描二维码。
如果您启用“弱光增强”,它会在光线较暗时自动开启,在光线较暗时关闭。
应用可以在光线昏暗的环境下录制预览流,以保存明亮的视频。
您可以在 Camera2 中或通过相机扩展使用弱光提升。本文档介绍了如何搭配使用“弱光增强”与 Camera2。如果设备支持,您还可以将“低光增强”与夜间模式相机扩展搭配使用。
检查是否有空房
在使用弱光增强之前,请检查设备是否支持该模式。如果有可用,“低光增强”是 camera2.CameraCharacteristics.CONTROL_AE_AVAILABLE_MODES
中列出的曝光模式之一。(低光增强是自身的自动曝光设置,因为其他自动曝光设置与低光增强执行的预览亮度不兼容。)
因此,如需检查是否可使用“弱光增强”,请调用 CameraCharacteristics.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_MODES)
并检查返回的模式是否包含 ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY
:
Kotlin
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 }
Java
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 }
启用弱光增强
如需在 Camera2 会话中启用弱光提升,请将 CaptureRequest.CONTROL_AE_MODE
设置为 ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY
。之后,您需要确认“弱光增强”已开启;您可以通过查看 CaptureResult.CONTROL_AE_MODE
字段执行此操作。您需要进行检查,因为“弱光提升”功能并不与所有相机配置都兼容。例如,出于 FPS 方面的考虑,高速录制不支持低光提升。如果“低光提升”功能未开启,您可能需要更改摄像头配置,然后重试。
Kotlin
val captureRequestBuilder = camera.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 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) == CameraMetadata.CONTROL_AE_MODE_ON_LOW_LIGHT_BOOST_BRIGHTNESS_PRIORITY } }, cameraHandler )
Java
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 );
显示器弱光增强
“低光增强”功能会在弱光条件下使预览视频流变亮,并且如果环境亮度足以进行正常拍摄,则不会产生任何效果。您可以通过查看 CaptureResult.CONTROL_LOW_LIGHT_BOOST_STATE
字段来确认“弱光增强”当前是否处于启用状态。如果您已开启“低光增强”功能,并且它当前处于活跃状态,则该字段设置为 CameraMetadata.CONTROL_LOW_LIGHT_BOOST_STATE_ACTIVE
。然后,可能会显示月亮图标或其他一些指示,表明预览正在变亮。
Kotlin
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) == CameraMetadata.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 )
Java
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) == CameraMetadata.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 );