标签：android service android-camera2
我正在使用camera2 API.我需要在没有预览的情况下在服务中拍照.它有效,但照片曝光不好.图片很暗或有时非常浅.如何修复代码以使照片质量更高？我正在使用前置摄像头.
public class Camera2Service extends Service
{
protected static final String TAG = "myLog";
protected static final int CAMERACHOICE = CameraCharacteristics.LENS_FACING_BACK;
protected CameraDevice cameraDevice;
protected CameraCaptureSession session;
protected ImageReader imageReader;
protected CameraDevice.StateCallback cameraStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice camera) {
Log.d(TAG, "CameraDevice.StateCallback onOpened");
cameraDevice = camera;
actOnReadyCameraDevice();
}
@Override
public void onDisconnected(@NonNull CameraDevice camera) {
Log.w(TAG, "CameraDevice.StateCallback onDisconnected");
}
@Override
public void one rror(@NonNull CameraDevice camera, int error) {
Log.e(TAG, "CameraDevice.StateCallback one rror " + error);
}
};
protected CameraCaptureSession.StateCallback sessionStateCallback = new CameraCaptureSession.StateCallback() {
@Override
public void onReady(CameraCaptureSession session) {
Camera2Service.this.session = session;
try {
session.setRepeatingRequest(createCaptureRequest(), null, null);
} catch (CameraAccessException e) {
Log.e(TAG, e.getMessage());
}
}
@Override
public void onConfigured(CameraCaptureSession session) {
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
}
};
protected ImageReader.OnImageAvailableListener onImageAvailableListener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
Log.d(TAG, "onImageAvailable");
Image img = reader.acquireLatestImage();
if (img != null) {
processImage(img);
img.close();
}
}
};
public void readyCamera() {
CameraManager manager = (CameraManager) getSystemService(CAMERA_SERVICE);
try {
String pickedCamera = getCamera(manager);
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
return;
}
manager.openCamera(pickedCamera, cameraStateCallback, null);
imageReader = ImageReader.newInstance(1920, 1088, ImageFormat.JPEG, 2 /* images buffered */);
imageReader.setOnImageAvailableListener(onImageAvailableListener, null);
Log.d(TAG, "imageReader created");
} catch (CameraAccessException e){
Log.e(TAG, e.getMessage());
}
}
public String getCamera(CameraManager manager){
try {
for (String cameraId : manager.getCameraIdList()) {
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
int cOrientation = characteristics.get(CameraCharacteristics.LENS_FACING);
if (cOrientation != CAMERACHOICE) {
return cameraId;
}
}
} catch (CameraAccessException e){
e.printStackTrace();
}
return null;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand flags " + flags + " startId " + startId);
readyCamera();
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onCreate() {
Log.d(TAG,"onCreate service");
super.onCreate();
}
public void actOnReadyCameraDevice()
{
try {
cameraDevice.createCaptureSession(Arrays.asList(imageReader.getSurface()), sessionStateCallback, null);
} catch (CameraAccessException e){
Log.e(TAG, e.getMessage());
}
}
@Override
public void onDestroy() {
try {
session.abortCaptures();
} catch (CameraAccessException e){
Log.e(TAG, e.getMessage());
}
session.close();
}
private void processImage(Image image){
//Process image data
ByteBuffer buffer;
byte[] bytes;
boolean success = false;
File file = new File(Environment.getExternalStorageDirectory() + "/Pictures/image.jpg");
FileOutputStream output = null;
if(image.getFormat() == ImageFormat.JPEG) {
buffer = image.getPlanes()[0].getBuffer();
bytes = new byte[buffer.remaining()]; // makes byte array large enough to hold image
buffer.get(bytes); // copies image from buffer to byte array
try {
output = new FileOutputStream(file);
output.write(bytes); // write the byte array to file
j++;
success = true;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
image.close(); // close this to free up buffer for other images
if (null != output) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
protected CaptureRequest createCaptureRequest() {
try {
CaptureRequest.Builder builder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
builder.addTarget(imageReader.getSurface());
return builder.build();
} catch (CameraAccessException e) {
Log.e(TAG, e.getMessage());
return null;
}
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
}
解决方法:
谢尔盖,我复制了你的代码,事实上我能够重现这个问题.我从Google Pixel 2(Android 8.1)中获得了完全黑色的图片.
但是,我已成功解决了黑皮特问题如下：
首先,如果有人想知道,你实际上不需要任何Activity,或任何预览UI元素,就像有关Camera API声明的许多其他线程一样！对于已弃用的Camera v1 API,过去曾经如此.现在,使用新的Camera v2 API,我所需要的只是前台服务.
为了开始捕获过程,我使用了以下代码：
CaptureRequest.Builder builder = cameraDevice.createCaptureRequest (CameraDevice.TEMPLATE_VIDEO_SNAPSHOT);
builder.set (CaptureRequest.CONTROL_MODE, CaptureRequest.CONTROL_MODE_AUTO);
builder.set (CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);
builder.addTarget (imageReader.getSurface ());
captureRequest = builder.build ();
然后,在ImageReader.onImageAvailable中,我跳过了前N张图片(意思是我没有保存它们).我让会话运行,捕获更多的图片而不保存它们.
这使相机有足够的时间自动逐渐调整曝光参数.然后,在N忽略照片后,我保存了一张照片,这张照片通常是曝光的,而不是黑色照片.
N常数的值取决于硬件的特性.因此,您需要通过实验确定N的理想值.您还可以使用基于直方图的启发式自动化.在实验开始时,不要害怕只有在经过数百毫秒的校准后才开始保存.
最后,在许多类似的主题中,人们建议等待,例如创建会话后500毫秒,然后只拍一张照片.这没有用.一个人必须让相机运行并让它快速拍摄许多照片(以最快的速度拍摄).为此,只需使用setRepeatingRequest方法(与原始代码一样).
希望这可以帮助.
标签：android,service,android-camera2 来源： https://codeday.me/bug/20190701/1350650.html
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