我试图从Java的下一页转换文本检测示例。原始代码是C ++。
https://github.com/opencv/opencv/blob/master/samples/dnn/text_detection.cpp
但是在Java中转换以下几行（cpp文件中的131-136）时，我遇到了问题：
...
const float* scoresData = scores.ptr<float>(0, 0, y);
const float* x0_data = geometry.ptr<float>(0, 0, y);
const float* x1_data = geometry.ptr<float>(0, 1, y);
...
我尝试使用openCV Mat类中的每种方法，但大多数方法都会引发异常！
到目前为止，我的代码如下：
Net net = Dnn.readNet("C:\\frozen_east_text_detection.pb");
Mat blob = Dnn.blobFromImage(resizedImg, 1.0, resizedImg.size(), new Scalar(123.68, 116.78, 103.94), true,
false);
net.setInput(blob);
List<Mat> outs = new ArrayList<>();
net.forward(outs, LAYER_NAMES);
Mat scores = outs.get(0);
Mat geometry = outs.get(1);
int numRows = scores.size(2);
int numCols = scores.size(3);
List<RotatedRect> boxes = new ArrayList<>();
List<Double> confidences = new ArrayList<>();
System.out.printf("numRows = %d\n", scores.size(2));
System.out.printf("numCols = %d\n", scores.size(3));
我对指针不是很熟悉，但是我能理解的是scores本机对象似乎是一个4-D数组，但是它是Java中的一个类，并且在Java中无法解决具有索引的类，例如所示的C ++或如下所示的python（将cpp程序转换为另一个网站上的python）：
for y in range(0, numRows):
scoresData = scores[0, 0, y]
xData0 = geometry[0, 0, y]
xData1 = geometry[0, 1, y]
xData2 = geometry[0, 2, y]
xData3 = geometry[0, 3, y]
anglesData = geometry[0, 4, y]
答案 0 :(得分：2)
这是我在this gist的berak处找到的Java等价代码：
Mat scoresData = scores.row(y);
Mat x0Data = geometry.submat(0, height, 0, width).row(y);
Mat x1Data = geometry.submat(height, 2 * height, 0, width).row(y);
Mat x2Data = geometry.submat(2 * height, 3 * height, 0, width).row(y);
Mat x3Data = geometry.submat(3 * height, 4 * height, 0, width).row(y);
Mat anglesData = geometry.submat(4 * height, 5 * height, 0, width).row(y);
这是Java中完整的文本检测代码：
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.opencv.core.Core;
import org.opencv.core.*;
import org.opencv.core.MatOfFloat;
import org.opencv.core.MatOfByte;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.dnn.*;
import org.opencv.dnn.Dnn;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
import org.opencv.utils.*;
public class SimpleSample {
static {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
}
public static void main(String[] args) {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
float scoreThresh = 0.5f;
float nmsThresh = 0.4f;
// Model from https://github.com/argman/EAST
// You can find it here : https://github.com/opencv/opencv_extra/blob/master/testdata/dnn/download_models.py#L309
Net net = Dnn.readNetFromTensorflow("c:/data/mdl/frozen_east_text_detection.pb");
// input image
Mat frame = Imgcodecs.imread("nantext.png");
Imgproc.cvtColor(frame, frame, Imgproc.COLOR_RGBA2RGB);
Size siz = new Size(320, 320);
int W = (int)(siz.width / 4); // width of the output geometry / score maps
int H = (int)(siz.height / 4); // height of those. the geometry has 4, vertically stacked maps, the score one 1
Mat blob = Dnn.blobFromImage(frame, 1.0,siz, new Scalar(123.68, 116.78, 103.94), true, false);
net.setInput(blob);
List<Mat> outs = new ArrayList<>(2);
List<String> outNames = new ArrayList<String>();
outNames.add("feature_fusion/Conv_7/Sigmoid");
outNames.add("feature_fusion/concat_3");
net.forward(outs, outNames);
// Decode predicted bounding boxes.
Mat scores = outs.get(0).reshape(1, H);
// My lord and savior : http://answers.opencv.org/question/175676/javaandroid-access-4-dim-mat-planes/
Mat geometry = outs.get(1).reshape(1, 5 * H); // don't hardcode it !
List<Float> confidencesList = new ArrayList<>();
List<RotatedRect> boxesList = decode(scores, geometry, confidencesList, scoreThresh);
// Apply non-maximum suppression procedure.
MatOfFloat confidences = new MatOfFloat(Converters.vector_float_to_Mat(confidencesList));
RotatedRect[] boxesArray = boxesList.toArray(new RotatedRect[0]);
MatOfRotatedRect boxes = new MatOfRotatedRect(boxesArray);
MatOfInt indices = new MatOfInt();
Dnn.NMSBoxesRotated(boxes, confidences, scoreThresh, nmsThresh, indices);
// Render detections
Point ratio = new Point((float)frame.cols()/siz.width, (float)frame.rows()/siz.height);
int[] indexes = indices.toArray();
for(int i = 0; i<indexes.length;++i) {
RotatedRect rot = boxesArray[indexes[i]];
Point[] vertices = new Point[4];
rot.points(vertices);
for (int j = 0; j < 4; ++j) {
vertices[j].x *= ratio.x;
vertices[j].y *= ratio.y;
}
for (int j = 0; j < 4; ++j) {
Imgproc.line(frame, vertices[j], vertices[(j + 1) % 4], new Scalar(0, 0,255), 1);
}
}
Imgcodecs.imwrite("out.png", frame);
}
private static List<RotatedRect> decode(Mat scores, Mat geometry, List<Float> confidences, float scoreThresh) {
// size of 1 geometry plane
int W = geometry.cols();
int H = geometry.rows() / 5;
//System.out.println(geometry);
//System.out.println(scores);
List<RotatedRect> detections = new ArrayList<>();
for (int y = 0; y < H; ++y) {
Mat scoresData = scores.row(y);
Mat x0Data = geometry.submat(0, H, 0, W).row(y);
Mat x1Data = geometry.submat(H, 2 * H, 0, W).row(y);
Mat x2Data = geometry.submat(2 * H, 3 * H, 0, W).row(y);
Mat x3Data = geometry.submat(3 * H, 4 * H, 0, W).row(y);
Mat anglesData = geometry.submat(4 * H, 5 * H, 0, W).row(y);
for (int x = 0; x < W; ++x) {
double score = scoresData.get(0, x)[0];
if (score >= scoreThresh) {
double offsetX = x * 4.0;
double offsetY = y * 4.0;
double angle = anglesData.get(0, x)[0];
double cosA = Math.cos(angle);
double sinA = Math.sin(angle);
double x0 = x0Data.get(0, x)[0];
double x1 = x1Data.get(0, x)[0];
double x2 = x2Data.get(0, x)[0];
double x3 = x3Data.get(0, x)[0];
double h = x0 + x2;
double w = x1 + x3;
Point offset = new Point(offsetX + cosA * x1 + sinA * x2, offsetY - sinA * x1 + cosA * x2);
Point p1 = new Point(-1 * sinA * h + offset.x, -1 * cosA * h + offset.y);
Point p3 = new Point(-1 * cosA * w + offset.x, sinA * w + offset.y); // original trouble here !
RotatedRect r = new RotatedRect(new Point(0.5 * (p1.x + p3.x), 0.5 * (p1.y + p3.y)), new Size(w, h), -1 * angle * 180 / Math.PI);
detections.add(r);
confidences.add((float) score);
}
}
}
return detections;
}
}