Extracting measures on each line from a note

Question

I would like to know a way to extract an individual line of measures. I'm not sure if an algorithm for this already exists, so I thought about scanning the notes from left to right, extracting all the white spaces above and below the measures line.

I am not looking for a way to convert notes to MusicXML or to extract other useful information. No, in fact, I mean a regular document. I need to separate paragraphs. I am not interested in the information contained in the paragraph, but simply separating them separately from the regions of the document. In this case, the paragraph will be one line of measures. I do not need individual measures, but all measures on each line of notes.

This is one of the results that I would like to get from a full note, but without a title, composer, etc.

Answer 1

If you have notes in a PDF file, I would use Apache PDFBox to get images from the input PDF file containing notes, then find the coordinates the whole stroke you need, with the selected image determine the coordinates to crop the image and manipulate it until get the desired result.

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 */); } } } 

Here is sample code available in Apache PDFBox.

 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: [e-mail] ">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 ); } } 

Now, to crop the image, you can use:

 /** * 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); } } 

which is available on this page and.

There is another option for parsing images inside a pdf file, look at this code specifically this