我尝试使用tessract / tess-two库创建一个带有OCR扫描仪的应用程序，我已成功访问手机摄像头，我可以进行手动对焦但是当我拍摄时图片出现以下错误：
07-18 19:07:06.335 2585-2585/com.fastnetserv.myapp D/DBG_com.fastnetserv.myapp.MainActivity: Picture taken
07-18 19:07:06.335 2585-2585/com.fastnetserv.myapp D/DBG_com.fastnetserv.myapp.MainActivity: Got null data
07-18 19:07:06.405 2585-2585/com.fastnetserv.myapp D/DBG_com.fastnetserv.myapp.MainActivity: Picture taken
07-18 19:07:06.426 2585-2585/com.fastnetserv.myapp D/DBG_com.fastnetserv.myapp.MainActivity: Got bitmap
07-18 19:07:06.427 2585-11599/com.fastnetserv.myapp E/DBG_com.fastnetserv.myapp.TessAsyncEngine: Error passing parameter to execute(context, bitmap)
07-18 19:07:14.111 2585-2585/com.fastnetserv.myapp D/DBG_com.fastnetserv.myapp.CameraUtils: CameraEngine Stopped
这里是CameraFragment代码：
package com.fastnetserv.myapp;
import android.content.Context;
import android.graphics.Bitmap;
import android.hardware.Camera;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import com.googlecode.tesseract.android.TessBaseAPI;
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link //CameraFragment.//OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link CameraFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class CameraFragment extends Fragment implements SurfaceHolder.Callback, View.OnClickListener,
Camera.PictureCallback, Camera.ShutterCallback {
static final String TAG = "DBG_" + MainActivity.class.getName();
Button shutterButton;
Button focusButton;
FocusBoxView focusBox;
SurfaceView cameraFrame;
CameraEngine cameraEngine;
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public CameraFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment CameraFragment.
*/
// TODO: Rename and change types and number of parameters
public static CameraFragment newInstance(String param1, String param2) {
CameraFragment fragment = new CameraFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_camera, container, false);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
try {
mListener = (OnFragmentInteractionListener) context;
} catch (ClassCastException e) {
throw new ClassCastException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
// Camera Code
public String detectText(Bitmap bitmap) {
TessDataManager.initTessTrainedData(getActivity());
TessBaseAPI tessBaseAPI = new TessBaseAPI();
String path = "/mnt/sdcard/com.fastnetserv.myapp/tessdata/ita.traineddata";
Log.d(TAG, "Check data path: " + path);
tessBaseAPI.setDebug(true);
tessBaseAPI.init(path, "ita"); //Init the Tess with the trained data file, with english language
//For example if we want to only detect numbers
tessBaseAPI.setVariable(TessBaseAPI.VAR_CHAR_WHITELIST, "1234567890");
tessBaseAPI.setVariable(TessBaseAPI.VAR_CHAR_BLACKLIST, "!@#$%^&*()_+=-qwertyuiop[]}{POIU" +
"YTREWQasdASDfghFGHjklJKLl;L:'\"\\|~`xcvXCVbnmBNM,./<>?");
tessBaseAPI.setImage(bitmap);
String text = tessBaseAPI.getUTF8Text();
//Log.d(TAG, "Got data: " + result);
tessBaseAPI.end();
return text;
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
Log.d(TAG, "Surface Created - starting camera");
if (cameraEngine != null && !cameraEngine.isOn()) {
cameraEngine.start();
}
if (cameraEngine != null && cameraEngine.isOn()) {
Log.d(TAG, "Camera engine already on");
return;
}
cameraEngine = CameraEngine.New(holder);
cameraEngine.start();
Log.d(TAG, "Camera engine started");
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
@Override
public void onResume() {
super.onResume();
cameraFrame = (SurfaceView) getActivity().findViewById(R.id.camera_frame);
shutterButton = (Button) getActivity().findViewById(R.id.shutter_button);
focusBox = (FocusBoxView) getActivity().findViewById(R.id.focus_box);
focusButton = (Button) getActivity().findViewById(R.id.focus_button);
shutterButton.setOnClickListener(this);
focusButton.setOnClickListener(this);
SurfaceHolder surfaceHolder = cameraFrame.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
cameraFrame.setOnClickListener(this);
}
@Override
public void onPause() {
super.onPause();
if (cameraEngine != null && cameraEngine.isOn()) {
cameraEngine.stop();
}
SurfaceHolder surfaceHolder = cameraFrame.getHolder();
surfaceHolder.removeCallback(this);
}
@Override
public void onClick(View v) {
if(v == shutterButton){
if(cameraEngine != null && cameraEngine.isOn()){
cameraEngine.takeShot(this, this, this);
}
}
if(v == focusButton){
if(cameraEngine!=null && cameraEngine.isOn()){
cameraEngine.requestFocus();
}
}
}
@Override
public void onPictureTaken(byte[] data, Camera camera) {
Log.d(TAG, "Picture taken");
if (data == null) {
Log.d(TAG, "Got null data");
return;
}
Bitmap bmp = Tools.getFocusedBitmap(getActivity(), camera, data, focusBox.getBox());
Log.d(TAG, "Got bitmap");
new TessAsyncEngine().executeOnExecutor(AsyncTask.SERIAL_EXECUTOR, this, bmp);
}
@Override
public void onShutter() {
}
}
这里是TessAsyncEngine：
package com.fastnetserv.myapp;
import android.app.Activity;
import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.util.Log;
import com.fastnetserv.myapp.ImageDialog;
import com.fastnetserv.myapp.Tools;
/**
* Created by Fadi on 6/11/2014.
*/
public class TessAsyncEngine extends AsyncTask<Object, Void, String> {
static final String TAG = "DBG_" + TessAsyncEngine.class.getName();
private Bitmap bmp;
private Activity context;
@Override
protected String doInBackground(Object... params) {
try {
if(params.length < 2) {
Log.e(TAG, "Error passing parameter to execute - missing params");
return null;
}
if(!(params[0] instanceof Activity) || !(params[1] instanceof Bitmap)) {
Log.e(TAG, "Error passing parameter to execute(context, bitmap)");
return null;
}
context = (Activity)params[0];
bmp = (Bitmap)params[1];
if(context == null || bmp == null) {
Log.e(TAG, "Error passed null parameter to execute(context, bitmap)");
return null;
}
int rotate = 0;
if(params.length == 3 && params[2]!= null && params[2] instanceof Integer){
rotate = (Integer) params[2];
}
if(rotate >= -180 && rotate <= 180 && rotate != 0)
{
bmp = Tools.preRotateBitmap(bmp, rotate);
Log.d(TAG, "Rotated OCR bitmap " + rotate + " degrees");
}
TessEngine tessEngine = TessEngine.Generate(context);
bmp = bmp.copy(Bitmap.Config.ARGB_8888, true);
String result = tessEngine.detectText(bmp);
Log.d(TAG, result);
return result;
} catch (Exception ex) {
Log.d(TAG, "Error: " + ex + "\n" + ex.getMessage());
}
return null;
}
@Override
protected void onPostExecute(String s) {
if(s == null || bmp == null || context == null)
return;
ImageDialog.New()
.addBitmap(bmp)
.addTitle(s)
.show(context.getFragmentManager(), TAG);
super.onPostExecute(s);
}
}
我已经按照本教程（http://www.codeproject.com/Tips/840623/Android-Character-Recognition）进行了操作，但由于我对Android缺乏了解，可能会忘记一些事情
答案 0 :(得分：1)
不需要if(context == null || bmp == null)，因为您已使用instanceof测试了这些值。
但我猜你的主要问题是将this从Fragment传递为Activity参数，而不是。{/ p>
要修复..我总体上会尝试不要乱扔Activity指针，因为那些在android上的生命周期非常有限。我有一个tess-two的应用程序，我不记得曾经需要Activity来初始化它（虽然我通常是从原生C ++开始，所以YMMV）。
这个电话不仅仅是Context吗？如果是，我建议改为getApplicationContext()值。我认为这也可以直接或间接地从Fragment访问。
很抱歉没有尝试使用您的代码，但这是您可以轻松调试的内容。
还有一个关于android和tesseract用法的说明。什么是Tools.getFocusedBitmap？它会合理地削减图片吗？如果它保持全尺寸，并且你的相机设置为全尺寸，那么你将在5-10 + MP位图附近投掷，这在Android中意味着几乎立即击中内存不足（OOM）。要么将相机设置为相当低的分辨率，要么尽快将照片的设计部分剪切掉并放下整个图像，理想情况下是处理的第一步。
此外，您可能需要重新考虑整个问题，并尝试使用Google Play服务中的官方Google Text API。
https://developers.google.com/android/reference/com/google/android/gms/vision/text/Text
这是全新的补充，我猜它会使用第二代Tesseract引擎进行最新改进，因此很有可能获得更好的结果和更好的速度，而不是tess-two。
我认为它只能从Android 4.4访问，只能在具有Google Play服务的设备上访问，并且跨平台很糟糕，所以我在我的项目中仍然使用tess-two，因为我还需要支持iOS和Windows Phone。
一般来说，我不相信没有来源的东西，没有来源的SW是僵尸，当你使用它时已经死了（最多需要30-50y才能死），这是浪费这些程序员的时间和技巧。