有没有一种方法可以在数据库中存储OpenCV/javacv Mat对象？

zvokhttg  于 2024-01-05  发布在  Java
关注(0)|答案(4)|浏览(202)

在阅读了无数的文档并试图理解有关opencv/javacv提取关键点的示例之后，使用一些DescriptorExtractor计算特征以将输入图像与一堆图像进行匹配，以查看输入图像是其中之一还是其中之一的一部分，我认为，我们应该在计算后存储Mat对象。
我将使用Emily Webb'的代码作为示例：
String smallUrl =“rsz_our-mobile-planet-us-infographic_infographics_lg_unerela.jpg”; String largeUrl =“our-mobile-planet-us-infographic_infographics_lg.jpg”;

  1. IplImage image = cvLoadImage(largeUrl,CV_LOAD_IMAGE_UNCHANGED );
  2. IplImage image2 = cvLoadImage(smallUrl,CV_LOAD_IMAGE_UNCHANGED ); 
  4. CvMat descriptorsA = new CvMat(null);
  5. CvMat descriptorsB = new CvMat(null);
  7. final FastFeatureDetector ffd = new FastFeatureDetector(40, true);
  8. final KeyPoint keyPoints = new KeyPoint();
  9. final KeyPoint keyPoints2 = new KeyPoint();
  11. ffd.detect(image, keyPoints, null);
  12. ffd.detect(image2, keyPoints2, null);
  14. System.out.println("keyPoints.size() : "+keyPoints.size());
  15. System.out.println("keyPoints2.size() : "+keyPoints2.size());
  16.  // BRISK extractor = new  BRISK();
  17.  //BriefDescriptorExtractor extractor = new BriefDescriptorExtractor();
  18. FREAK extractor = new FREAK();
  20. extractor.compute(image, keyPoints, descriptorsA);
  21. extractor.compute(image2, keyPoints2, descriptorsB);
  23. System.out.println("descriptorsA.size() : "+descriptorsA.size());
  24. System.out.println("descriptorsB.size() : "+descriptorsB.size());
  26. DMatch dmatch = new DMatch();
  27. //FlannBasedMatcher matcher = new FlannBasedMatcher();
  28. //DescriptorMatcher matcher = new DescriptorMatcher();
  30. BFMatcher matcher = new BFMatcher();
  31. matcher.match(descriptorsA, descriptorsB, dmatch, null);
  33. System.out.println(dmatch.capacity());

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我的问题是：我如何在DB中存储mptorsA（或mptorsB）--在opencv的java实现中-？（它们是在extractor.compute（image，keyPoints，mptorsA）之后获得的Mat对象;）
我知道Mat对象在Java实现中不是可序列化的对象，但可以肯定的是，如果你想将一个图像与一组存档图像相匹配，你必须提取存档的描述符并将它们存储在某个地方以供功能使用。

Java

4条答案

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vecaoik1

vecaoik11#

经过一些更多的搜索，我发现一些链接在http://answers.opencv.org/question/8873/best-way-to-store-a-mat-object-in-android/
虽然答案主要针对Android设备，并参考了之前关于保存关键点（Saving ORB feature vectors using OpenCV4Android (java API)）的问题，但下面代码中的答案“从Mat对象到xml和xml到Mat对象”似乎是有效的：

  1. import org.opencv.core.CvType;
  2. import org.opencv.core.Mat;
  3. import org.w3c.dom.Document;
  4. import org.w3c.dom.Element;
  5. import org.w3c.dom.Node;
  6. import org.w3c.dom.NodeList;
  8. import javax.xml.parsers.DocumentBuilderFactory;
  9. import javax.xml.transform.OutputKeys;
  10. import javax.xml.transform.Transformer;
  11. import javax.xml.transform.TransformerFactory;
  12. import javax.xml.transform.dom.DOMSource;
  13. import javax.xml.transform.stream.StreamResult;
  14. import java.io.File;
  15. import java.util.Locale;
  16. import java.util.Scanner;
  18. public class TaFileStorage {
  19.     // static
  20.     public static final int READ = 0;
  21.     public static final int WRITE = 1;
  23.     // varaible
  24.     private File file;
  25.     private boolean isWrite;
  26.     private Document doc;
  27.     private Element rootElement;
  29.     public TaFileStorage() {
  30.         file = null;
  31.         isWrite = false;
  32.         doc = null;
  33.         rootElement = null;
  34.     }
  36.     // read or write
  37.     public void open(String filePath, int flags ) {
  38.         try {
  39.             if( flags == READ ) {
  40.                 open(filePath);
  41.             }
  42.             else {
  43.                 create(filePath);
  44.             }
  45.         } catch(Exception e) {
  46.             e.printStackTrace();
  47.         }
  49.     }
  51.     // read only
  52.     public void open(String filePath) {
  53.         try {
  54.             file = new File(filePath);
  55.             if( file == null || file.isFile() == false ) {
  56.                 System.err.println("Can not open file: " + filePath );
  57.             }
  58.             else {
  59.                 isWrite = false;
  60.                 doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(file);
  61.                 doc.getDocumentElement().normalize();
  62.             }
  63.         } catch(Exception e) {
  64.             e.printStackTrace();
  65.         }
  67.     }
  69.     // write only
  70.     public void create(String filePath) {
  71.         try {
  72.             file = new File(filePath);
  73.             if( file == null ) {
  74.                 System.err.println("Can not wrtie file: " + filePath );
  75.             }
  76.             else {
  77.                 isWrite = true;
  78.                 doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
  80.                 rootElement = doc.createElement("opencv_storage");
  81.                 doc.appendChild(rootElement);
  82.             }
  83.         } catch(Exception e) {
  84.             e.printStackTrace();
  85.         }
  86.     }
  88.     public Mat readMat(String tag) {
  89.         if( isWrite ) {
  90.             System.err.println("Try read from file with write flags");
  91.             return null;
  92.         }
  94.         NodeList nodelist = doc.getElementsByTagName(tag);
  95.         Mat readMat = null;
  97.         for( int i = 0 ; i<nodelist.getLength() ; i++ ) {
  98.             Node node = nodelist.item(i);
  100.             if( node.getNodeType() == Node.ELEMENT_NODE ) {
  101.                 Element element = (Element)node;
  103.                 String type_id = element.getAttribute("type_id");
  104.                 if( "opencv-matrix".equals(type_id) == false) {
  105.                     System.out.println("Fault type_id ");
  106.                 }
  108.                 String rowsStr = element.getElementsByTagName("rows").item(0).getTextContent();
  109.                 String colsStr = element.getElementsByTagName("cols").item(0).getTextContent();
  110.                 String dtStr = element.getElementsByTagName("dt").item(0).getTextContent();
  111.                 String dataStr = element.getElementsByTagName("data").item(0).getTextContent();
  113.                 int rows = Integer.parseInt(rowsStr);
  114.                 int cols = Integer.parseInt(colsStr);
  115.                 int type = CvType.CV_8U;
  117.                 Scanner s = new Scanner(dataStr);
  118.                 s.useLocale(Locale.US);
  120.                 if( "f".equals(dtStr) ) {
  121.                     type = CvType.CV_32F;
  122.                     readMat = new Mat( rows, cols, type );
  123.                     float fs[] = new float[1];
  124.                     for( int r=0 ; r<rows ; r++ ) {
  125.                         for( int c=0 ; c<cols ; c++ ) {
  126.                             if( s.hasNextFloat() ) {
  127.                                 fs[0] = s.nextFloat();
  128.                             }
  129.                             else {
  130.                                 fs[0] = 0;
  131.                                 System.err.println("Unmatched number of float value at rows="+r + " cols="+c);
  132.                             }
  133.                             readMat.put(r, c, fs);
  134.                         }
  135.                     }
  136.                 }
  137.                 else if( "i".equals(dtStr) ) {
  138.                     type = CvType.CV_32S;
  139.                     readMat = new Mat( rows, cols, type );
  140.                     int is[] = new int[1];
  141.                     for( int r=0 ; r<rows ; r++ ) {
  142.                         for( int c=0 ; c<cols ; c++ ) {
  143.                             if( s.hasNextInt() ) {
  144.                                 is[0] = s.nextInt();
  145.                             }
  146.                             else {
  147.                                 is[0] = 0;
  148.                                 System.err.println("Unmatched number of int value at rows="+r + " cols="+c);
  149.                             }
  150.                             readMat.put(r, c, is);
  151.                         }
  152.                     }
  153.                 }
  154.                 else if( "s".equals(dtStr) ) {
  155.                     type = CvType.CV_16S;
  156.                     readMat = new Mat( rows, cols, type );
  157.                     short ss[] = new short[1];
  158.                     for( int r=0 ; r<rows ; r++ ) {
  159.                         for( int c=0 ; c<cols ; c++ ) {
  160.                             if( s.hasNextShort() ) {
  161.                                 ss[0] = s.nextShort();
  162.                             }
  163.                             else {
  164.                                 ss[0] = 0;
  165.                                 System.err.println("Unmatched number of int value at rows="+r + " cols="+c);
  166.                             }
  167.                             readMat.put(r, c, ss);
  168.                         }
  169.                     }
  170.                 }
  171.                 else if( "b".equals(dtStr) ) {
  172.                     readMat = new Mat( rows, cols, type );
  173.                     byte bs[] = new byte[1];
  174.                     for( int r=0 ; r<rows ; r++ ) {
  175.                         for( int c=0 ; c<cols ; c++ ) {
  176.                             if( s.hasNextByte() ) {
  177.                                 bs[0] = s.nextByte();
  178.                             }
  179.                             else {
  180.                                 bs[0] = 0;
  181.                                 System.err.println("Unmatched number of byte value at rows="+r + " cols="+c);
  182.                             }
  183.                             readMat.put(r, c, bs);
  184.                         }
  185.                     }
  186.                 }
  187.             }
  188.         }
  189.         return readMat;
  190.     }
  192.     public void writeMat(String tag, Mat mat) {
  193.         try {
  194.             if( isWrite == false) {
  195.                 System.err.println("Try write to file with no write flags");
  196.                 return;
  197.             }
  199.             Element matrix = doc.createElement(tag);
  200.             matrix.setAttribute("type_id", "opencv-matrix");
  201.             rootElement.appendChild(matrix);
  203.             Element rows = doc.createElement("rows");
  204.             rows.appendChild( doc.createTextNode( String.valueOf(mat.rows()) ));
  206.             Element cols = doc.createElement("cols");
  207.             cols.appendChild( doc.createTextNode( String.valueOf(mat.cols()) ));
  209.             Element dt = doc.createElement("dt");
  210.             String dtStr;
  211.             int type = mat.type();
  212.             if(type == CvType.CV_32F ) { // type == CvType.CV_32FC1
  213.                 dtStr = "f";
  214.             }
  215.             else if( type == CvType.CV_32S ) { // type == CvType.CV_32SC1
  216.                 dtStr = "i";
  217.             }
  218.             else if( type == CvType.CV_16S  ) { // type == CvType.CV_16SC1
  219.                 dtStr = "s";
  220.             }
  221.             else if( type == CvType.CV_8U ){ // type == CvType.CV_8UC1 
  222.                 dtStr = "b";
  223.             }
  224.             else {
  225.                 dtStr = "unknown";
  226.             }
  227.             dt.appendChild( doc.createTextNode( dtStr ));
  229.             Element data = doc.createElement("data");
  230.             String dataStr = dataStringBuilder( mat );
  231.             data.appendChild( doc.createTextNode( dataStr ));
  233.             // append all to matrix
  234.             matrix.appendChild( rows );
  235.             matrix.appendChild( cols );
  236.             matrix.appendChild( dt );
  237.             matrix.appendChild( data );
  239.         } catch(Exception e) {
  240.             e.printStackTrace();
  241.         }
  242.     }
  244.     private String dataStringBuilder(Mat mat) {
  245.         StringBuilder sb = new StringBuilder();
  246.         int rows = mat.rows();
  247.         int cols = mat.cols();
  248.         int type = mat.type();
  250.         if( type == CvType.CV_32F ) {
  251.             float fs[] = new float[1];
  252.             for( int r=0 ; r<rows ; r++ ) {
  253.                 for( int c=0 ; c<cols ; c++ ) {
  254.                     mat.get(r, c, fs);
  255.                     sb.append( String.valueOf(fs[0]));
  256.                     sb.append( ' ' );
  257.                 }
  258.                 sb.append( '\n' );
  259.             }       
  260.         }
  261.         else if( type == CvType.CV_32S ) {
  262.             int is[] = new int[1];
  263.             for( int r=0 ; r<rows ; r++ ) {
  264.                 for( int c=0 ; c<cols ; c++ ) {
  265.                     mat.get(r, c, is);
  266.                     sb.append( String.valueOf(is[0]));
  267.                     sb.append( ' ' );
  268.                 }
  269.                 sb.append( '\n' );
  270.             }
  271.         }
  272.         else if( type == CvType.CV_16S ) {
  273.             short ss[] = new short[1];
  274.             for( int r=0 ; r<rows ; r++ ) {
  275.                 for( int c=0 ; c<cols ; c++ ) {
  276.                     mat.get(r, c, ss);
  277.                     sb.append( String.valueOf(ss[0]));
  278.                     sb.append( ' ' );
  279.                 }
  280.                 sb.append( '\n' );
  281.             }
  282.         }
  283.         else if( type == CvType.CV_8U ) {
  284.             byte bs[] = new byte[1];
  285.             for( int r=0 ; r<rows ; r++ ) {
  286.                 for( int c=0 ; c<cols ; c++ ) {
  287.                     mat.get(r, c, bs);
  288.                     sb.append( String.valueOf(bs[0]));
  289.                     sb.append( ' ' );
  290.                 }
  291.                 sb.append( '\n' );
  292.             }
  293.         }       
  294.         else {
  295.             sb.append("unknown type\n");
  296.         }
  298.         return sb.toString();
  299.     }
  301.     public void release() {
  302.         try {
  303.             if( isWrite == false) {
  304.                 System.err.println("Try release of file with no write flags");
  305.                 return;
  306.             }
  308.             DOMSource source = new DOMSource(doc);
  310.             StreamResult result = new StreamResult(file);
  312.             // write to xml file
  313.             Transformer transformer = TransformerFactory.newInstance().newTransformer();
  314.             transformer.setOutputProperty(OutputKeys.INDENT, "yes");
  316.             // do it
  317.             transformer.transform(source, result);
  318.         } catch(Exception e) {
  319.             e.printStackTrace();
  320.         }
  321.     }
  322. }

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gt0wga4j

gt0wga4j2#

由于Thorben提出的代码在我的情况下很慢，我使用序列化提出了以下代码。

  1. public final void saveMat(String path, Mat mat) {
  2.     File file = new File(path).getAbsoluteFile();
  3.     file.getParentFile().mkdirs();
  4.     try {
  5.         int cols = mat.cols();
  6.         float[] data = new float[(int) mat.total() * mat.channels()];
  7.         mat.get(0, 0, data);
  8.         try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(path))) {
  9.             oos.writeObject(cols);
  10.             oos.writeObject(data);
  11.             oos.close();
  12.         }
  13.     } catch (IOException | ClassCastException ex) {
  14.         System.err.println("ERROR: Could not save mat to file: " + path);
  15.         Logger.getLogger(this.class.getName()).log(Level.SEVERE, null, ex);
  16.     }
  17. }
  19. public final Mat loadMat(String path) {
  20.     try {
  21.         int cols;
  22.         float[] data;
  23.         try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(path))) {
  24.             cols = (int) ois.readObject();
  25.             data = (float[]) ois.readObject();
  26.         }
  27.         Mat mat = new Mat(data.length / cols, cols, CvType.CV_32F);
  28.         mat.put(0, 0, data);
  29.         return mat;
  30.     } catch (IOException | ClassNotFoundException | ClassCastException ex) {
  31.         System.err.println("ERROR: Could not load mat from file: " + path);
  32.         Logger.getLogger(this.class.getName()).log(Level.SEVERE, null, ex);
  33.     }
  34.     return null;
  35. }

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对于描述符你OpenCV使用垫的浮动，在其他情况下，你必须相应地修改代码这个列表中找到here：

  1. CV_8U and CV_8S -> byte[]
  2. CV_16U and CV_16S -> short[]
  3. CV_32S -> int[]
  4. CV_32F -> float[]
  5. CV_64F-> double[]

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35g0bw71

35g0bw713#

搜索完所有的答案后，我编辑了一些代码，它似乎工作。我用它来存储筛选描述符到HBase。

  1. public static byte[] serializeMat(Mat mat) {
  2.         ByteArrayOutputStream bos = new ByteArrayOutputStream();
  3.         try {
  4.             float[] data = new float[(int) mat.total() * mat.channels()];
  5.             mat.get(0, 0, data);
  6.             ObjectOutput out = new ObjectOutputStream(bos);
  7.             out.writeObject(data);
  8.             out.close();
  9.             // Get the bytes of the serialized object
  10.             byte[] buf = bos.toByteArray();
  11.             return buf;
  12.         } catch (IOException ioe) {
  13.             ioe.printStackTrace();
  14.             return null;
  15.         }
  16.     }

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qnakjoqk

qnakjoqk4#

我还遇到了Javaorg.opencv没有原生OpenCV的FileStorage功能的问题。

  1. package net.sf.jaer.util;
  3. import com.esotericsoftware.yamlbeans.YamlException;
  4. import com.esotericsoftware.yamlbeans.YamlReader;
  5. import com.esotericsoftware.yamlbeans.YamlWriter;
  6. import java.io.FileReader;
  7. import java.io.FileNotFoundException;
  8. import java.io.FileWriter;
  9. import java.io.IOException;
  10. import java.util.ArrayList;
  11. import java.util.List;
  12. import java.util.Map;
  13. import java.util.logging.Logger;
  15. import org.opencv.core.CvType;
  16. import org.opencv.core.Mat;
  18. /**
  19.  * Adapted from
  20.  * https://stackoverflow.com/questions/34297676/how-to-load-opencv-matrices-saved-with-filestorage-in-java
  21.  * 
  22.  * using
  23.  * https://github.com/EsotericSoftware/yamlbeans
  24.  *
  25.  * @author https://stackoverflow.com/users/3303546/cecilia
  26.  */
  27. public class YamlMatFileStorage {
  29.     private static final Logger log = Logger.getLogger("YamlMatLoader");
  31.     // Mat cannot be used directly because it is a native object and yamlbeans only deals with Java objects
  32.     protected static class MatStorage {
  34.         public int rows;
  35.         public int cols;
  36.         public String dt;
  37.         public List<String> data;
  39.         // The empty constructor is required by YamlReader
  40.         public MatStorage() {
  41.         }
  43.         public double[] getData() {
  44.             double[] dataOut = new double[data.size()];
  45.             for (int i = 0; i < dataOut.length; i++) {
  46.                 dataOut[i] = Double.parseDouble(data.get(i));
  47.             }
  49.             return dataOut;
  50.         }
  52.         public void putData(Mat m) {
  53.             rows = m.rows();
  54.             cols = m.cols();
  55.             data = new ArrayList();
  56.             for (int r = 0; r < rows; r++) {
  57.                 for (int c = 0; c < cols; c++) {
  58.                     data.add(Double.toString(m.get(r, c)[0]));
  59.                 }
  60.             }
  62.         }
  63.     }
  65.     /**
  66.      * Reads a Mat from a YAML file
  67.      *
  68.      * @param path path to YAML file
  69.      * @return the Mat
  70.      */
  71.     public Mat readMatYml(String path) throws FileNotFoundException, YamlException, IOException {
  72.         Mat m=null;
  73.         try (YamlReader reader = new YamlReader(new FileReader(path))) {
  74.             MatStorage matStorage = (MatStorage) reader.read();
  75.             // Create a new Mat to hold the extracted data
  76.             m = new Mat(matStorage.rows, matStorage.cols, CvType.CV_32FC1);
  77.             m.put(0, 0, matStorage.getData());
  78.             log.info(String.format("From file %s loaded Mat %s", path, m));
  79.         }
  80.         return m;
  81.     }
  83.     // Loading function
  84.     /**
  85.      * Reads a Mat from a YAML file
  86.      *
  87.      * @param path path to YAML file
  88.      * @param m the Mat to write
  89.      * @throws java.io.IOException
  90.      * @throws com.esotericsoftware.yamlbeans.YamlException
  91.      */
  92.     public void writeMatYml(String path, Mat m) throws IOException, YamlException {
  93.         try (YamlWriter writer = new YamlWriter(new FileWriter(path))) {
  94.             // write the Mat
  95.             MatStorage ms = new MatStorage();
  96.             ms.putData(m);
  97.             writer.write(ms);
  98.         }
  99.         log.info(String.format("Wrote Mat %s to file %s", m, path));
  100.     }
  102. }

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存储的文件看起来像这样：

  1. !net.sf.jaer.util.YamlMatFileStorage$MatStorage
  2. cols: 3
  3. data: 
  4. - 1735.0830676085973
  5. - 0.0
  6. - 173.80815300223972
  7. - 0.0
  8. - 1720.885058317215
  9. - 147.99521279976508
  10. - 0.0
  11. - 0.0
  12. - 1.0
  13. rows: 3

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