android - 在异步方法中使用 Tesseract 代码

Question

我正在构建一个在异步调用中使用 Tesseract 库的 Android 应用。执行 OCR 的方法非常有效，直到我在不同的线程上调用它。我得到的异常(exception)是:

*1: java.Lang.Unsatisfiedlinkerror: Library opencv_core not found; tried [/vendor/lib/libopencv_core.so, /system/lib/libopencv_core.so]

2: System.TypeInitializationException: An exception was thrown by the type initializer for Emgu.CV.CvInvoke*

我使用的代码:

protected override void OnStart()
{
    base.OnStart();
    ImageView testimage = FindViewById<ImageView>(Resource.Id.TestImage);
    testimage.SetImageBitmap(ScanImage);

    ThreadPool.QueueUserWorkItem(state => {
        PerformOCR();
    });
}

protected void PerformOCR() //object state
{
    //Get the tesseract directory
    Java.IO.File myDir = Android.OS.Environment.ExternalStorageDirectory;
    Tesseract _ocr = new Tesseract(myDir.ToString() + "/tesseract/", "eng", Tesseract.OcrEngineMode.OEM_TESSERACT_CUBE_COMBINED);

    //Image optimization
    Image<Gray, Byte> passport = new Image<Gray, Byte>(ScanImage);
    Image<Gray, float> sobel = passport.Sobel(1, 0, 5);
    sobel.Add(passport.Sobel(0, 1, 5));
    passport = passport.Add(sobel.Convert<Gray, byte>());           

    _ocr.Recognize(passport);
    string text = _ocr.GetText();
    RunOnUiThread(() => SpecificationsText.Text = text); 
}

OCR 中使用的图像存储在静态类中。

Answer 1

好的，我已经解决了我自己的问题。

出于某种原因，tesseract 初始化无法在异步方法中完成，因此通过从方法调用中删除初始化并在其他地方进行初始化，我的问题得到了解决。

protected override void OnStart()
{
    base.OnStart();
    ImageView testimage = FindViewById<ImageView>(Resource.Id.TestImage);
    testimage.SetImageBitmap(ScanImage);

    //Get the tesseract directory
    Java.IO.File myDir = Android.OS.Environment.ExternalStorageDirectory;
    Tesseract _ocr = new Tesseract(myDir.ToString() + "/tesseract/", "eng", Tesseract.OcrEngineMode.OEM_TESSERACT_CUBE_COMBINED);

    ThreadPool.QueueUserWorkItem(state => {
        PerformOCR(_ocr);
    });
}

protected void PerformOCR(Tesseract _ocr)
{
    //Image optimization
    Image<Gray, Byte> passport = new Image<Gray, Byte>(ScanImage);
    Image<Gray, float> sobel = passport.Sobel(1, 0, 5);
    sobel.Add(passport.Sobel(0, 1, 5));
    passport = passport.Add(sobel.Convert<Gray, byte>());           

    _ocr.Recognize(passport);
    string text = _ocr.GetText();
    RunOnUiThread(() => SpecificationsText.Text = text); 
}