Java 从乐谱中提取每行的度量值

我想知道一种提取单个度量线的方法。我不确定是否已经存在这样的算法，所以我想从左到右扫描一张乐谱，从一行度量的上方和下方提取所有空白

我不是在寻找将乐谱转换为MusicXML或提取其他有用信息的方法。不，基本上我处理的是一份常规文件。我需要把段落分开。我对该段所传达的信息不感兴趣，只是将它们与文件的区域分开。在这种情况下，一段将是一行措施。我不需要单独的措施，但所有的措施对每一行的乐谱

这是一个输出，我想从全张音乐，但没有标题，作曲家等。

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假设您有PDF文件中的乐谱，我会使用从包含乐谱的输入PDF文件中获取图像，然后找到您需要的整个酒吧的坐标，使用选定的图像定义坐标以裁剪图像并对其进行操作，直到获得所需的结果

PDDocument document = null; 
document = PDDocument.load(inFile); 
List pages = document.getDocumentCatalog().getAllPages();
Iterator iter = pages.iterator(); 
while (iter.hasNext()) {
            PDPage page = (PDPage) iter.next();
            PDResources resources = page.getResources();
            Map pageImages = resources.getImages();
            if (pageImages != null) { 
                Iterator imageIter = pageImages.keySet().iterator();
                while (imageIter.hasNext()) {
                    String key = (String) imageIter.next();
                    PDXObjectImage image = (PDXObjectImage) pageImages.get(key);
                    image.write2OutputStream(/* some output stream */);
                }
            }
}

下面是ApachePDFBox中可用的示例代码

import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.encryption.AccessPermission;
import org.apache.pdfbox.pdmodel.encryption.StandardDecryptionMaterial;
import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObject;
import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObjectForm;
import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObjectImage;

/**
 * This will read a read pdf and extract images. <br/><br/>
 *
 * usage: java org.apache.pdfbox.ExtractImages &lt;pdffile&gt; &lt;password&gt; [imageprefix]
 *
 * @author  <a href="mailto:ben@benlitchfield.com">Ben Litchfield</a>
 * @version $Revision: 1.7 $
 */
public class ExtractImages
{
    private int imageCounter = 1;

    private static final String PASSWORD = "-password";
    private static final String PREFIX = "-prefix";
    private static final String ADDKEY = "-addkey";
    private static final String NONSEQ = "-nonSeq";

    private ExtractImages()
    {
    }

    /**
     * This is the entry point for the application.
     *
     * @param args The command-line arguments.
     *
     * @throws Exception If there is an error decrypting the document.
     */
    public static void main( String[] args ) throws Exception
    {
        ExtractImages extractor = new ExtractImages();
        extractor.extractImages( args );
    }

    private void extractImages( String[] args ) throws Exception
    {
        if( args.length < 1 || args.length > 4 )
        {
            usage();
        }
        else
        {
            String pdfFile = null;
            String password = "";
            String prefix = null;
            boolean addKey = false;
            boolean useNonSeqParser = false;
            for( int i=0; i<args.length; i++ )
            {
                if( args[i].equals( PASSWORD ) )
                {
                    i++;
                    if( i >= args.length )
                    {
                        usage();
                    }
                    password = args[i];
                }
                else if( args[i].equals( PREFIX ) )
                {
                    i++;
                    if( i >= args.length )
                    {
                        usage();
                    }
                    prefix = args[i];
                }
                else if( args[i].equals( ADDKEY ) )
                {
                    addKey = true;
                }
                else if( args[i].equals( NONSEQ ) )
                {
                    useNonSeqParser = true;
                }
                else
                {
                    if( pdfFile == null )
                    {
                        pdfFile = args[i];
                    }
                }
            }
            if(pdfFile == null)
            {
                usage();
            }
            else
            {
                if( prefix == null && pdfFile.length() >4 )
                {
                    prefix = pdfFile.substring( 0, pdfFile.length() -4 );
                }

                PDDocument document = null;

                try
                {
                    if (useNonSeqParser)
                    {
                        document = PDDocument.loadNonSeq(new File(pdfFile), null, password);
                    }
                    else
                    {
                        document = PDDocument.load( pdfFile );

                        if( document.isEncrypted() )
                        {
                            StandardDecryptionMaterial spm = new StandardDecryptionMaterial(password);
                            document.openProtection(spm);
                        }
                    }
                    AccessPermission ap = document.getCurrentAccessPermission();
                    if( ! ap.canExtractContent() )
                    {
                        throw new IOException(
                            "Error: You do not have permission to extract images." );
                    }

                    List pages = document.getDocumentCatalog().getAllPages();
                    Iterator iter = pages.iterator();
                    while( iter.hasNext() )
                    {
                        PDPage page = (PDPage)iter.next();
                        PDResources resources = page.getResources();
                        // extract all XObjectImages which are part of the page resources
                        processResources(resources, prefix, addKey);
                    }
                }
                finally
                {
                    if( document != null )
                    {
                        document.close();
                    }
                }
            }
        }
    }

    private void processResources(PDResources resources, String prefix, boolean addKey) throws IOException
    {
        if (resources == null)
        {
            return;
        }
        Map<String, PDXObject> xobjects = resources.getXObjects();
        if( xobjects != null )
        {
            Iterator<String> xobjectIter = xobjects.keySet().iterator();
            while( xobjectIter.hasNext() )
            {
                String key = xobjectIter.next();
                PDXObject xobject = xobjects.get( key );
                // write the images
                if (xobject instanceof PDXObjectImage)
                {
                    PDXObjectImage image = (PDXObjectImage)xobject;
                    String name = null;
                    if (addKey) 
                    {
                        name = getUniqueFileName( prefix + "_" + key, image.getSuffix() );
                    }
                    else 
                    {
                        name = getUniqueFileName( prefix, image.getSuffix() );
                    }
                    System.out.println( "Writing image:" + name );
                    image.write2file( name );
                }
                // maybe there are more images embedded in a form object
                else if (xobject instanceof PDXObjectForm)
                {
                    PDXObjectForm xObjectForm = (PDXObjectForm)xobject;
                    PDResources formResources = xObjectForm.getResources();
                    processResources(formResources, prefix, addKey);
                }
            }
        }
    }

    private String getUniqueFileName( String prefix, String suffix )
    {
        String uniqueName = null;
        File f = null;
        while( f == null || f.exists() )
        {
            uniqueName = prefix + "-" + imageCounter;
            f = new File( uniqueName + "." + suffix );
            imageCounter++;
        }
        return uniqueName;
    }

    /**
     * This will print the usage requirements and exit.
     */
    private static void usage()
    {
        System.err.println( "Usage: java org.apache.pdfbox.ExtractImages [OPTIONS] <PDF file>\n" +
            "  -password  <password>        Password to decrypt document\n" +
            "  -prefix  <image-prefix>      Image prefix(default to pdf name)\n" +
            "  -addkey                      add the internal image key to the file name\n" +
            "  -nonSeq                      Enables the new non-sequential parser\n" +
            "  <PDF file>                   The PDF document to use\n"
            );
        System.exit( 1 );
    }

}

在和中提供

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还有其他选项可以解析pdf文件中的图像，请特别查看

您还需要员工上方/下方的注释吗？有时，这些可能会有点纠结。“提取单个度量线”是什么意思？不是一个音乐术语。不是一个直接的答案，但谷歌搜索“python sheet music ocr”会让我想到另一个堆栈问题：：：这可能会帮助你解决这个问题实际上有点类似于描述如何在文本中找到“河流”（线性空白流）的问题。我建议你也检查一下这个答案：不确定为什么选择这个答案，因为它完全无法回答用户的问题。

/**
     * Crop the main image according to this rectangle, and scale it to the
     * correct size for a thumbnail.
     */
    public InputStream cropAndScale(InputStream mainImageStream,
            CropRectangle crop) {
        try {
            RenderedOp mainImage = loadImage(mainImageStream);
            RenderedOp opaqueImage = makeImageOpaque(mainImage);
            RenderedOp croppedImage = cropImage(opaqueImage, crop);
            RenderedOp scaledImage = scaleImage(croppedImage);
            byte[] jpegBytes = encodeAsJpeg(scaledImage);
            return new ByteArrayInputStream(jpegBytes);
        } catch (Exception e) {
            throw new IllegalStateException("Failed to scale the image", e);
        }
    }