Question

我正在尝试使用Android Camera2 API在弱光条件下使用Flash捕获图像。问题在于我拍摄的第一张照片的光线条件似乎锁定了一些值，而我不知道如何控制它们。

如果我在光线充足的条件下拍摄图片，那么一切都会按需进行。如果以后拍摄低照度照片，我会得到很好的结果。
如果我在弱光条件下拍摄第一张照片，则照片变成白色，然后，预览保持完全曝光过度。接下来拍的每张照片都是白色。

我试图设置CaptureRequest的几个参数（LOCK_AE_MODE等），但我只是不知道控制哪些参数以及何时控制。

这就是我拍照的方式：

protected void takePicture() {
        if (null == cameraDevice) {
            Log.e(TAG, "cameraDevice is null");
            return; }

        image_available=false;
        try {
            List<Surface> outputSurfaces = new ArrayList<Surface>(2);
            outputSurfaces.add(imageReader.getSurface());
            outputSurfaces.add(new Surface(textureView.getSurfaceTexture()));

            final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
            captureBuilder.addTarget(imageReader.getSurface());

            captureBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER, CameraMetadata.CONTROL_AE_PRECAPTURE_TRIGGER_START);
            captureBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START);
            captureBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AE_MODE_ON_ALWAYS_FLASH);


            // Orientation
            int rotation = getActivity().getWindowManager().getDefaultDisplay().getRotation();
            captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));


            imageReader.setOnImageAvailableListener(mOnImageAvailableListener, mBackgroundHandler);

            cameraDevice.createCaptureSession(outputSurfaces, new CameraCaptureSession.StateCallback() {

                public void onConfigured(CameraCaptureSession session) {
                    try {
                        session.capture(captureBuilder.build(), captureCallback, mBackgroundHandler);
                    } catch (CameraAccessException e) {
                        e.printStackTrace();
                    }
                }
                public void onConfigureFailed(CameraCaptureSession session) {
                }
            }, mBackgroundHandler);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

这是我的预览：


protected void createCameraPreview() {
        try {
            SurfaceTexture texture = textureView.getSurfaceTexture();
            assert texture != null;
            texture.setDefaultBufferSize(imageDimension.getWidth(), imageDimension.getHeight());
            Surface surface = new Surface(texture);
            captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
            captureRequestBuilder.addTarget(surface);

            //captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AE_MODE_OFF);
            //captureRequestBuilder.set(CaptureRequest.SENSOR_SENSITIVITY, ??);
            //captureRequestBuilder.set(CaptureRequest.CONTROL_AE_LOCK, true);


            captureRequestBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER, CameraMetadata.CONTROL_AE_PRECAPTURE_TRIGGER_START);
            captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CameraMetadata.CONTROL_AF_MODE_CONTINUOUS_PICTURE);



            cameraDevice.createCaptureSession(Arrays.asList(surface),  new CameraCaptureSession.StateCallback() {
                @Override
                public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
                    if (null == cameraDevice) {
                        return; }

                    try {
                        cameraCaptureSession.capture(captureRequestBuilder.build(), null, mBackgroundHandler);
                    } catch (CameraAccessException e) {
                        e.printStackTrace();
                    }
                    cameraCaptureSessions = cameraCaptureSession;
                    updatePreview();
                }

                @Override
                public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
                    Log.e(TAG, "Configuration change");
                }
            }, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }
    protected void updatePreview() {
        if (null == cameraDevice) {
            Log.e(TAG, "updatePreview error, return");
        }
        captureRequestBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);

        try {
            cameraCaptureSessions.setRepeatingRequest(captureRequestBuilder.build(), null, mBackgroundHandler);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

我的目标是始终获得良好的效果，就像在良好的光照条件下拍摄第一张照片一样。在开始预览之前，有什么方法可以手动设置和锁定相同的参数吗？

Camera2：在弱光条件下拍摄第一张照片后预览曝光过度

0 个答案: