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我正在尝试使用 tessract/tess-two 库创建一个带有 OCR 扫描仪的应用程序，我已经成功访问​​了手机摄像头，我可以进行手动对焦，但是当我拍照时出现以下错误：

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);
    }
}

我已按照本教程（http://www.codeproject.com/Tips/840623/Android-Character-Recognition）进行操作，但可能由于我对 Android 缺乏了解而忘记了一些事情

4

1 回答 1

1

这if(context == null || bmp == null)不是必需的，因为您已经使用instanceof.

但我猜你的主要问题是this从 Fragment 作为Activity参数传递，但事实并非如此。

修复..我总体上会尽量不要乱扔Activity指针，因为它们在 android 上的生命周期非常有限。我有一个带有 tess-two 的应用程序，我不记得曾经需要 Activity 来初始化它（尽管通常我从本机 C++ 初始化它，所以是 YMMV）。

不只是Context那个电话的需要吗？如果是，我建议改为转向getApplicationContext()价值。我认为这也可以直接或间接访问Fragment。

很抱歉没有尝试您的代码，但这是您可以很容易地调试的东西。

关于 android 和 tesseract 用法的另一条说明。是什么Tools.getFocusedBitmap？它会合理地减少图片吗？如果它保持全尺寸，并且您的相机设置为全尺寸，那么您将折腾大约 5-10+MP 位图，这在 Android 中意味着几乎立即达到内存不足 (OOM)。要么将相机设置为相当低的分辨率，要么尽快剪掉照片的设计部分并丢弃整个图像，理想情况下作为处理的第一步。

此外，您可能想重新考虑整个 tess-two 的事情，并尝试来自 Google play services 的官方 Google Text API。

https://developers.google.com/android/reference/com/google/android/gms/vision/text/Text

它是全新添加的，内部我猜它会使用最新改进的第二代 Tesseract 引擎，因此很有可能获得比 tess-two 更好的结果和更快的速度。

我认为它只能从 Android 4.4 访问，并且只能在具有 Google Play 服务的设备上访问，而且跨平台很糟糕，所以我在我的项目中使用 tess-two - 因为我还必须支持 iOS 和 Windows Phone。

而且一般我不相信没有源的东西，没有源的SW是僵尸，在你使用它时已经死了（最多需要30-50年才能死），这是浪费时间和技能那些程序员。

于 2016-07-18T17:47:50.387 回答