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使用新的 CameraX API，我尝试使用public void takePicture(final OnImageCapturedListener listener)方法在内存中拍摄图片，然后将给定的图像转换为 OpenCV Mat。

虽然当我尝试以高质量捕获图像时，我能够在 Image Analyzer 中成功将图像转换为 Mat 存在问题，但 getPlanes 返回一个只有一个项目的数组（其中图像分析器，我得到三个 SurfacePlane 项目）和看似破碎：

伊姆古尔

package com.example.scanner;

import android.content.pm.PackageManager;
import android.graphics.ImageFormat;
import android.media.Image;
import android.os.Bundle;
import android.util.Rational;
import android.util.Size;
import android.view.TextureView;
import android.view.ViewGroup;
import android.widget.Toast;

import org.opencv.core.CvType;
import org.opencv.core.Mat;

import java.nio.ByteBuffer;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.camera.core.CameraX;
import androidx.camera.core.ImageAnalysis;
import androidx.camera.core.ImageAnalysisConfig;
import androidx.camera.core.ImageCapture;
import androidx.camera.core.ImageCaptureConfig;
import androidx.camera.core.ImageProxy;
import androidx.camera.core.Preview;
import androidx.camera.core.PreviewConfig;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.lifecycle.LifecycleOwner;

public class CameraXActivity extends AppCompatActivity {

    private final String[] REQUIRED_PERMISSIONS = new String[]{"android.permission.CAMERA", "android.permission.WRITE_EXTERNAL_STORAGE"};
    //array w/ permissions from manifest
    TextureView mSurfaceView;
    private int REQUEST_CODE_PERMISSIONS = 10; //arbitrary number, can be changed accordingly

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

        mSurfaceView = findViewById(R.id.action_sync);

        if (allPermissionsGranted()) {
            startCamera(); //start camera if permission has been granted by user
        } else {
            ActivityCompat.requestPermissions(this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS);
        }
    }

    private void startCamera() {
        androidx.camera.core.CameraX.unbindAll();

        /* start preview */
        int aspRatioW = mSurfaceView.getWidth(); // get width of screen
        int aspRatioH = mSurfaceView.getHeight(); // get height
        Rational asp = new Rational(aspRatioW, aspRatioH); // aspect ratio
        Size screen = new Size(aspRatioW, aspRatioH); // size of the screen

        PreviewConfig pConfig = new PreviewConfig.Builder()
                .setTargetAspectRatio(asp)
                .setTargetResolution(screen)
                .setLensFacing(androidx.camera.core.CameraX.LensFacing.BACK)
                .build();
        Preview preview = new Preview(pConfig); //lets build it


        preview.setOnPreviewOutputUpdateListener(
                new Preview.OnPreviewOutputUpdateListener() {
                    @Override
                    public void onUpdated(Preview.PreviewOutput output) {
                        mSurfaceView.setSurfaceTexture(output.getSurfaceTexture());
                    }
                });

        ImageAnalysisConfig imgAConfig = new ImageAnalysisConfig.Builder()
                .setImageReaderMode(ImageAnalysis.ImageReaderMode.ACQUIRE_LATEST_IMAGE)
                .setLensFacing(CameraX.LensFacing.BACK)
                .setTargetResolution(new android.util.Size(2480, 3508))
                .build();
        ImageAnalysis analysis = new ImageAnalysis(imgAConfig);

        analysis.setAnalyzer(
                new ImageAnalysis.Analyzer() {
                    @Override
                    public void analyze(ImageProxy image, int rotationDegrees) {

                        Mat mat = imageToMat(image.getImage()); // no errors here!

                    }
                });

        preview.setOnPreviewOutputUpdateListener(
                new Preview.OnPreviewOutputUpdateListener() {
                    //to update the surface texture we have to destroy it first, then re-add it
                    @Override
                    public void onUpdated(Preview.PreviewOutput output) {
                        ViewGroup parent = (ViewGroup) mSurfaceView.getParent();
                        parent.removeView(mSurfaceView);
                        parent.addView(mSurfaceView, 0);

                        mSurfaceView.setSurfaceTexture(output.getSurfaceTexture());
                    }
                });

        ImageCaptureConfig imgCapConfig =
                new ImageCaptureConfig.Builder()
                        .setCaptureMode(ImageCapture.CaptureMode.MIN_LATENCY)
                        .setLensFacing(CameraX.LensFacing.BACK)
                        .setTargetResolution(new android.util.Size(2480, 3508))
                        .build();
        final ImageCapture imgCap = new ImageCapture(imgCapConfig);

        // call after 5 seconds of starting
        new Thread(() -> {
            try {
                Thread.sleep(5000);
                imgCap.takePicture(new ImageCapture.OnImageCapturedListener() {
                    @Override
                    public void onCaptureSuccess(ImageProxy image, int rotationDegrees) {

                        Mat mat = imageToMat(image.getImage()); // ERROR HERE!

                    }

                    @Override
                    public void onError(ImageCapture.UseCaseError useCaseError, String message, @Nullable Throwable cause) {
                        // Error
                    }
                });
            } catch (Exception e) {
                System.err.println(e);
            }
        }).start();
        //bind to lifecycle:
        androidx.camera.core.CameraX.bindToLifecycle((LifecycleOwner) this, analysis, imgCap, preview);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        //start camera when permissions have been granted otherwise exit app
        if (requestCode == REQUEST_CODE_PERMISSIONS) {
            if (allPermissionsGranted()) {
                startCamera();
            } else {
                Toast.makeText(this, "Permissions not granted by the user.", Toast.LENGTH_SHORT).show();
                finish();
            }
        }
    }

    private boolean allPermissionsGranted() {
        //check if req permissions have been granted
        for (String permission : REQUIRED_PERMISSIONS) {
            if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
                return false;
            }
        }
        return true;
    }


    public static Mat imageToMat(Image image) {
        ByteBuffer buffer;
        int rowStride;
        int pixelStride;
        int width = image.getWidth();
        int height = image.getHeight();
        int offset = 0;

        Image.Plane[] planes = image.getPlanes();
        byte[] data = new byte[image.getWidth() * image.getHeight() * ImageFormat.getBitsPerPixel(ImageFormat.YUV_420_888) / 8];
        byte[] rowData = new byte[planes[0].getRowStride()];

        for (int i = 0; i < planes.length; i++) {
            buffer = planes[i].getBuffer();
            rowStride = planes[i].getRowStride();
            pixelStride = planes[i].getPixelStride();
            int w = (i == 0) ? width : width / 2;
            int h = (i == 0) ? height : height / 2;
            for (int row = 0; row < h; row++) {
                int bytesPerPixel = ImageFormat.getBitsPerPixel(ImageFormat.YUV_420_888) / 8;
                if (pixelStride == bytesPerPixel) {
                    int length = w * bytesPerPixel;
                    buffer.get(data, offset, length);

                    if (h - row != 1) {
                        buffer.position(buffer.position() + rowStride - length);
                    }
                    offset += length;
                } else {


                    if (h - row == 1) {
                        buffer.get(rowData, 0, width - pixelStride + 1);
                    } else {
                        buffer.get(rowData, 0, rowStride);
                    }

                    for (int col = 0; col < w; col++) {
                        data[offset++] = rowData[col * pixelStride];
                    }
                }
            }
        }

        Mat mat = new Mat(height + height / 2, width, CvType.CV_8UC1);
        mat.put(0, 0, data);

        return mat;
    }
}

尝试使用 1.0.0-alpha01 和最新 (1.0.0-alpha03) 版本的相机。最初，虽然问题在于 YUV 到 Mat 的转换或图像太大，但事实并非如此。

使用的手机是华为P20 Pro。

4

1 回答 1

3

找到导致此问题的问题。捕获的图像不是 Yuv，而是 JPEG 格式，如文档中所述。

要将 JPEG 转换为 Mat，可以使用以下代码：

imgCap.takePicture(new ImageCapture.OnImageCapturedListener() {
                @Override
                public void onCaptureSuccess(ImageProxy image, int rotationDegrees) {
                    ByteBuffer bb = image.getPlanes()[0].getBuffer();
                    byte[] buf = new byte[bb.remaining()];
                    bb.get(buf);

                    Mat mat = Imgcodecs.imdecode(new MatOfByte(buf), Imgcodecs.IMREAD_UNCHANGED);

                    // Do something with Mat...

                    image.close();
                }

                @Override
                public void onError(
                        ImageCapture.UseCaseError error, String message, @Nullable Throwable cause) {

                    // silently ingore error
                }
            });
于 2019-07-05T08:50:24.910 回答