我在我的应用程序中使用相机拍摄身份证照片，我有一个矩形的覆盖层，图像将被裁剪到该覆盖层上。问题是一旦捕获图像，图像质量就会降低。
我无法弄清楚到底发生了什么。在cutImage方法中，我正在剪切图像，但我认为我没有为该图像的分辨率做任何事情。
任何人都可以建议质量可能会下降的地方。
当用户单击拍照时，会调用takePicture。 拍照后，有一个“使用图片”按钮，即调用usePicture时。
cutImage方法用于基于预览裁剪图像。
关于如何阻止分辨率下降的任何建议将非常有帮助
protected void takePicture() {
Log.e(TAG, "takePicture started");
if(null == cameraDevice) {
Log.e(TAG, "cameraDevice is null");
return;
}
try {
ImageReader reader = ImageReader.newInstance(textureViewWidth, textureViewHeight, ImageFormat.JPEG, 1);
List<Surface> outputSurfaces = new ArrayList<Surface>(2);
outputSurfaces.add(reader.getSurface());
outputSurfaces.add(new Surface(textureView.getSurfaceTexture()));
final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(reader.getSurface());
captureBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
// Orientation
int rotation = getActivity().getWindowManager().getDefaultDisplay().getRotation();
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
ImageReader.OnImageAvailableListener readerListener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
Image image = null;
try {
image = reader.acquireLatestImage();
ByteBuffer buffer = image.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.capacity()];
buffer.get(bytes);
takenPictureBytes = bytes;
Log.d(TAG, "takenPictureBytes length - " + takenPictureBytes.length);
} catch (Exception e) {
Log.d(TAG, " onImageAvailable exception ");
e.printStackTrace();
} finally {
if (image != null) {
Log.d(TAG, " image closing");
image.close();
}
}
}
};
reader.setOnImageAvailableListener(readerListener, mBackgroundHandler);
final CameraCaptureSession.CaptureCallback captureListener = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
Log.d(TAG, "takePicture - camera capture session");
switchPanels(true);
progress.setVisibility(View.GONE);
}
};
cameraDevice.createCaptureSession(outputSurfaces, new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
try {
session.capture(captureBuilder.build(), captureListener, mBackgroundHandler);
} catch (CameraAccessException e) {
Log.d(TAG, "takePicture - onConfigured- camera access exception ");
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession session) {
Log.d(TAG, "takePicture - onConfigureFailed");
}
}, mBackgroundHandler);
} catch (CameraAccessException e) {
Log.d(TAG, "takePicture - CameraAccessException ");
e.printStackTrace();
}
}
private void usePicture() {
Log.d(TAG, "usePicture - started ");
if(null != takenPictureBytes ){
try{
String imagePath = null;
Bitmap bitmap = BitmapFactory.decodeByteArray(takenPictureBytes, 0, takenPictureBytes.length);
int bitmapByteCountUsePic = byteSizeOf(bitmap);
Matrix matrix = new Matrix();
matrix.postRotate(90);
Bitmap rotatedBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
if (isFrameMode) {
float withRatio = (float) rotatedBitmap.getWidth() / (float) textureViewWidth;
float heightRatio = (float) rotatedBitmap.getHeight() / (float) textureViewHeight;
Bitmap newImage = cutImage(rotatedBitmap, (int) (photoFrameView.getWidth() * withRatio), (int) (photoFrameView.getHeight() * heightRatio), withRatio);
int bitmapByteCountNewImage = byteSizeOf(newImage);
imagePath = saveBitmap(newImage);
} else {
imagePath = saveBitmap(rotatedBitmap);
}
TakePhotoFragment.TakePhotoFragmentEvent takePhotoFragmentEvent = new TakePhotoFragment.TakePhotoFragmentEvent();
takePhotoFragmentEvent.setImagePath(imagePath);
// send rxjava
//pop backstack
RxBus.getInstance().post(takePhotoFragmentEvent);
getActivity().getSupportFragmentManager().popBackStack();
}catch (Exception e){
Log.d(TAG, "usePicture - exception ");
e.printStackTrace();
}
}else{
Log.d(TAG, "usePicture - takenPictureBytes is null");
DialogUtil.showErrorSnackBar(getView(), R.string.retake_photo );
}
}
public Bitmap cutImage(final Bitmap bitmap, final int pixepWidth, final int pixelsHeight, float widthRatio) {
int bitmapByteCountCutImage = byteSizeOf(bitmap);
Bitmap output = createBitmap(pixepWidth, pixelsHeight, Bitmap.Config.ARGB_8888);
Bitmap original = bitmap;
final Paint paint = new Paint();
Canvas canvas = new Canvas(output);
int padding = (int) ((float) getResources().getDimensionPixelSize(R.dimen.double_padding) * widthRatio);
Rect rect = new Rect(padding, (original.getHeight() - pixelsHeight) / 2, padding + pixepWidth, original.getHeight() - (original.getHeight() - pixelsHeight) / 2);
final RectF cutedRect = new RectF(0, 0, pixepWidth, pixelsHeight);
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
canvas.drawBitmap(original, rect, cutedRect, paint);
return output;
}
private String saveBitmap(Bitmap bitmap) {
File pictureFileDir = getDir();
if (!pictureFileDir.exists() && !pictureFileDir.mkdirs()) {
Toast.makeText(getActivity(), "Can't create directory to save image.", Toast.LENGTH_LONG).show();
return null;
}
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyymmddhhmmssSSS");
String date = dateFormat.format(new Date());
String photoFile = "Picture_" + date + ".jpg";
String filename = pictureFileDir.getPath() + File.separator + photoFile;
File pictureFile = new File(filename);
try {
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(stream.toByteArray());
fos.close();
return pictureFile.getAbsolutePath();
} catch (Exception error) {
Log.d(TAG, "File" + filename + "not saved: " + error.getMessage());
}
return null;
}
答案 0 :(得分：0)
您正在以下代码中更改位图的大小/分辨率：
float withRatio = (float) rotatedBitmap.getWidth() / (float) textureViewWidth;
float heightRatio = (float) rotatedBitmap.getHeight() / (float) textureViewHeight;
Bitmap newImage = cutImage(rotatedBitmap, (int) (photoFrameView.getWidth() * withRatio), (int) (photoFrameView.getHeight() * heightRatio), withRatio);
int bitmapByteCountNewImage = byteSizeOf(newImage);
imagePath = saveBitmap(newImage);
放入一个断点，看看新的heightRatio和widthRatio是什么，以及photoFrameView.getWidth（）* withRatio的值是什么。我认为您会发现它与原始图像相比很小。我不确定为什么要使用textureViewWidth / Height计算比率，所以不必这样做。无论您在其中显示图像的是什么，都应该能够“填充”，而不必更改基础位图的大小，从而可以降低分辨率。
您可以签出此方法：
rawBitmap = ((BitmapDrawable)imageToLoad.getDrawable()).getBitmap();
theBitmap = Bitmap.createScaledBitmap(rawBitmap, 285, 313, false);