如何在 Camera X 支持庫中設置曝光補償？

Question

我正在使用 CameraX 庫單擊照片並想更改曝光設置。 如何設置曝光補償或更改所拍攝照片的曝光設置？

// Set up the capture use case to allow users to take photos
val imageCaptureConfig = ImageCaptureConfig.Builder().apply {
    setLensFacing(lensFacing)
    setCaptureMode(CaptureMode.MIN_LATENCY)
    // We request aspect ratio but no resolution to match preview config but letting
    // CameraX optimize for whatever specific resolution best fits requested capture mode
    setTargetAspectRatio(screenAspectRatio)
    // Set initial target rotation, we will have to call this again if rotation changes
    // during the lifecycle of this use case
    setTargetRotation(viewFinder.display.rotation)
}.build()


imageCapture = ImageCapture(imageCaptureConfig)

// Setup image analysis pipeline that computes average pixel luminance in real time
val analyzerConfig = ImageAnalysisConfig.Builder().apply {
    setLensFacing(lensFacing)
    // Use a worker thread for image analysis to prevent preview glitches
    setCallbackHandler(Handler(analyzerThread.looper))
    // In our analysis, we care more about the latest image than analyzing *every* image
    setImageReaderMode(ImageAnalysis.ImageReaderMode.ACQUIRE_LATEST_IMAGE)
    // Set initial target rotation, we will have to call this again if rotation changes
    // during the lifecycle of this use case
    setTargetRotation(viewFinder.display.rotation)
}.build()

Answer 1

val imageCaptureBuilder = ImageCapture.Builder().apply {
    setLensFacing(lensFacing)
    setCaptureMode(CaptureMode.MIN_LATENCY)
    // We request aspect ratio but no resolution to match preview config but letting
    // CameraX optimize for whatever specific resolution best fits requested capture mode
    setTargetAspectRatio(screenAspectRatio)
    // Set initial target rotation, we will have to call this again if rotation changes
    // during the lifecycle of this use case
    setTargetRotation(viewFinder.display.rotation)
}

Camera2Interop.Extender(imageCaptureBuilder).setCaptureRequestOption(
  CaptureRequest.CONTROL_AE_EXPOSURE_COMPENSATION, exposure)
  
imageCapture = imageCaptureBuilder.build()

其中exposure是您想要的價值

理想情況下，您應該查詢CONTROL_AE_COMPENSATION_RANGE以設置exposure的有效值。

Answer 2

CameraX 1.0.0-beta09為ExposureCompensation添加了實驗性接口

您可以通過以下方式設置曝光：

val camera = cameraProvider.bindToLifecycle(viewLifecycleOwner, cameraSelector, preview, imageCapture)
val cameraControl = camera.cameraControl
cameraControl.setExposureCompensationIndex(exposure)