谷歌 OCR 在特定领域工作

Question

我目前正在使用来自com.google.android.gms.vision 的SurfaceView 和CameraSource 来捕获图像上检测到的文本，但是由于它捕获了SurfaceView 区域上的所有内容，因此我需要丢弃一些恢复的内容。

目标是让SurfaceView 像下一张图片一样工作，忽略所有检测到的红叉区域中的文本，只给我蓝色方块上的东西。

这可能吗？

这是布局（没什么特别的）：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <SurfaceView
        android:id="@+id/fragment_surface"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

这里有关于类的 OCR 相关代码：

public class CameraActivity extends AppCompatActivity {

    private SurfaceView surfaceView;
    private CameraSource cameraSource;
    private StringBuilder builder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera);

        surfaceView = (SurfaceView) findViewById(R.id.fragment_surface);

        TextRecognizer recognizer = new TextRecognizer.Builder(getApplicationContext()).build();
        if (recognizer.isOperational()) {

            cameraSource = new CameraSource.Builder(getApplicationContext(), recognizer)
                    .setFacing(CameraSource.CAMERA_FACING_BACK)
                    .setRequestedPreviewSize(1280, 1024)
                    .setRequestedFps(15.0f)
                    .setAutoFocusEnabled(true)
                    .build();

            surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
                @Override
                public void surfaceCreated(SurfaceHolder holder) {
                    if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                        ActivityCompat.requestPermissions(CameraActivity.this, new String[]{Manifest.permission.CAMERA}, 100);
                        return;
                    }
                    try {
                        cameraSource.start(surfaceView.getHolder());
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

                @Override
                public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                    //
                }

                @Override
                public void surfaceDestroyed(SurfaceHolder holder) {
                    cameraSource.stop();
                }
            });
            recognizer.setProcessor(new Detector.Processor<TextBlock>() {
                @Override
                public void release() {
                    //
                }

                @Override
                public void receiveDetections(Detector.Detections<TextBlock> detections) {
                    final SparseArray<TextBlock> items = detections.getDetectedItems();
                    if (items.size() != 0) {
                        builder = new StringBuilder();
                        for (int i = 0; i < items.size(); i++) {
                            TextBlock it = items.valueAt(i);
                            builder.append(it.getValue());
                        }
                        String read = builder.toString().trim().replace(" ", "").replace("\n", "");

                        //It continues doing other things here
                    }
                }
            });
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case 100:
                if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    try {
                        if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                            return;
                        }
                        cameraSource.start(surfaceView.getHolder());
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                break;
        }
    }
}

Answer 1

当设备处于纵向模式（如您的图片中）时，非红色区域应该是相机预览的裁剪部分（填满整个屏幕），因此：

• 如果您想显示整个相机预览并仅在裁剪区域上执行 OCR：那么您必须获取 SurfaceView 的“屏幕截图”（完整区域），然后裁剪该区域以获得所需的即时像素李>
• intead，如果您只想显示裁剪区域（因为红色区域充满了其他界面、按钮、TextView 等）：那么您必须使用 SurfaceView 来仅渲染所需的部分通过使用 Matrix 参数在该特定位置进行相机预览

我建议您“升级”到 TextureView，这有点难以管理/使用，但允许通过在其内部纹理上使用矩阵来根据需要裁剪、缩放和缩放预览。

Answer 2

简介

我正在尝试对您现有的代码进行最小的更改，因此只需像现在一样扫描您的整个图像，并过滤掉超出范围的结果单词（或块）。

代码

使用rect.intersect 查找word 的bounding-box 并查看它是否在您的rectangle (rect) 中：

Rect yourRect = new Rect(10, 20, 30, 40);
rect.intersect(yourRect);//also see Drawable d = d.getBounds();

尝试将此代码添加到您的 @Override public void receiveDetections() 方法中：

        //Loop through each `Block`
        foreach (TextBlock textBlock in blocks)
        {
            IList<IText> textLines = textBlock.Components; 

            //loop Through each `Line`
            foreach (IText currentLine in textLines)
            {
                IList<IText>  words = currentLine.Components;

                //Loop through each `Word`
                foreach (IText currentword in words)
                {
                    //Get the Rectangle/BoundingBox of the word
                    RectF rect = new RectF(currentword.BoundingBox);

                   // Check if the word boundingBox is inside the area required

                  // using: rect.intersect(yourRect);
                  //...
                }

所以它看起来像这样：

        recognizer.setProcessor(new Detector.Processor<TextBlock>() {
            @Override
            public void release() {
                //
            }

            @Override
            public void receiveDetections(Detector.Detections<TextBlock> detections) {
                final SparseArray<TextBlock> items = detections.getDetectedItems();
                if (items.size() != 0) {
                    builder = new StringBuilder();
                    for (int i = 0; i < items.size(); i++) {
                        TextBlock it = items.valueAt(i);
                        builder.append(it.getValue());
                    }
                    String read = builder.toString().trim().replace(" ", "").replace("\n", "");

        List<TextBlock> blocks = new List<TextBlock>();

        TextBlock myItem = null;
        for (int i = 0; i < items.Size(); ++i)
        {
            myItem = (TextBlock)items.ValueAt(i);

            //Add All TextBlocks to the `blocks` List
            blocks.Add(myItem);

        }

        //Loop through each `Block`
        foreach (TextBlock textBlock in blocks)
        {
            IList<IText> textLines = textBlock.Components; 

            //loop Through each `Line`
            foreach (IText currentLine in textLines)
            {
                IList<IText>  words = currentLine.Components;

                //Loop through each `Word`
                foreach (IText currentword in words)
                {
                    //Get the Rectangle/BoundingBox of the word
                    RectF rect = new RectF(currentword.BoundingBox);

                   // Check if the word boundingBox is inside the area required

                  // using: rect.intersect(yourRect);
                  //put the word in a filtered list...
                }

            }

                    //It continues doing other things here
                }
            }
        });

只有六行代码！