I have created a small console application to do OCR on a .tiff image file, I have done this using tess4j.

public class JavaApplication10 { /** * @param args the command line arguments */ public static void main(String[] args) { File imageFile = new File("C:\\Users\\Manesh\\Desktop\\license_plate.tiff"); Tesseract instance = Tesseract.getInstance(); // JNA Interface Mapping // Tesseract1 instance = new Tesseract1(); // JNA Direct Mapping try { String result = instance.doOCR(imageFile); //Empty result System.out.println("hahahaha"); System.out.println("The result is: " + result); } catch (TesseractException e) { System.out.println("error:" + e); } } }

I'm not getting any value inside result, when I looked into the code of Tesseract class and inserted a couple of System.out.println those are also not getting printed in the console. My Tesseract code is given below.

public class Tesseract { private static Tesseract instance; private final static Rectangle EMPTY_RECTANGLE = new Rectangle(); private String language = "eng"; private String datapath = "tessdata"; private int psm = TessAPI.TessPageSegMode.PSM_AUTO; private boolean hocr; private int pageNum; private int ocrEngineMode = TessAPI.TessOcrEngineMode.OEM_DEFAULT; private Properties prop = new Properties(); public final static String htmlBeginTag = "<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\"" + " \"">\n" + "<html>\n<head>\n<title></title>\n" + "<meta http-equiv=\"Content-Type\" content=\"text/html;" + "charset=utf-8\" />\n<meta name='ocr-system' content='tesseract'/>\n" + "</head>\n<body>\n"; public final static String htmlEndTag = "</body>\n</html>\n"; private Tesseract() { System.setProperty("jna.encoding", "UTF8"); } public static synchronized Tesseract getInstance() { if (instance == null) { instance = new Tesseract(); } return instance; } public void setDatapath(String datapath) { this.datapath = datapath; } public void setLanguage(String language) { this.language = language; } public void setOcrEngineMode(int ocrEngineMode) { this.ocrEngineMode = ocrEngineMode; } public void setPageSegMode(int mode) { this.psm = mode; } public void setHocr(boolean hocr) { this.hocr = hocr; prop.setProperty("tessedit_create_hocr", hocr ? "1" : "0"); } public void setTessVariable(String key, String value) { prop.setProperty(key, value); } public String doOCR(File imageFile) throws TesseractException { System.out.println("hiiiiiii "); //not getting printed return doOCR(imageFile, null); } public String doOCR(File imageFile, Rectangle rect) throws TesseractException { try { System.out.println("be: "); //not getting printed return doOCR(ImageIOHelper.getIIOImageList(imageFile), rect); } catch (IOException ioe) { throw new TesseractException(ioe); } } public String doOCR(BufferedImage bi) throws TesseractException { return doOCR(bi, null); } public String doOCR(BufferedImage bi, Rectangle rect) throws TesseractException { IIOImage oimage = new IIOImage(bi, null, null); List<IIOImage> imageList = new ArrayList<IIOImage>(); imageList.add(oimage); return doOCR(imageList, rect); } public String doOCR(List<IIOImage> imageList, Rectangle rect) throws TesseractException { StringBuilder sb = new StringBuilder(); pageNum = 0; for (IIOImage oimage : imageList) { pageNum++; try { ByteBuffer buf = ImageIOHelper.getImageByteBuffer(oimage); RenderedImage ri = oimage.getRenderedImage(); String pageText = doOCR(ri.getWidth(), ri.getHeight(), buf, rect, ri.getColorModel().getPixelSize()); sb.append(pageText); } catch (IOException ioe) { //skip the problematic image System.err.println(ioe.getMessage()); } } if (hocr) { sb.insert(0, htmlBeginTag).append(htmlEndTag); } return sb.toString(); } public String doOCR(int xsize, int ysize, ByteBuffer buf, Rectangle rect, int bpp) throws TesseractException { TessAPI api = TessAPI.INSTANCE; TessAPI.TessBaseAPI handle = api.TessBaseAPICreate(); api.TessBaseAPIInit2(handle, datapath, language, ocrEngineMode); api.TessBaseAPISetPageSegMode(handle, psm); Enumeration em = prop.propertyNames(); while (em.hasMoreElements()) { String key = (String) em.nextElement(); api.TessBaseAPISetVariable(handle, key, prop.getProperty(key)); } int bytespp = bpp / 8; int bytespl = (int) Math.ceil(xsize * bpp / 8.0); api.TessBaseAPISetImage(handle, buf, xsize, ysize, bytespp, bytespl); if (rect != null && !rect.equals(EMPTY_RECTANGLE)) { api.TessBaseAPISetRectangle(handle, rect.x, rect.y, rect.width, rect.height); } Pointer utf8Text = hocr ? api.TessBaseAPIGetHOCRText(handle, pageNum - 1) : api.TessBaseAPIGetUTF8Text(handle); String str = utf8Text.getString(0); api.TessDeleteText(utf8Text); api.TessBaseAPIDelete(handle); return str; } }

I'm using tesseract for the first time please tell me what I'm doing wrong.

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1 Answer

For Tesseract you have to pass the exact image you want to do OCR on, for example, suppose you are reading the chest numbers of players, if you pass the cropped and gray scaled image of the chest number only it will read the text, where as if you pass the whole image it will not read. You can do this using. 

String doOCR(BufferedImage img, Rectangle rect);

Well i'm passing the cropped image directly so I'm not using the above method, My code looks like this rite now.

public class JavaApplication10 { /** * @param args the command line arguments */ public static void main(String[] args) { try { File imageFile = new File("C:\\Users\\Manesh\\Desktop\\116.jpg"); //This is a cropped image of a chest number. BufferedImage img = ImageIO.read(imageFile); //BufferedImageOp grayscaleConv = new ColorConvertOp(colorFrame.getColorModel().getColorSpace(), grayscaleConv.filter(colorFrame, grayFrame); Tesseract instance = Tesseract.getInstance(); // JNA Interface Mapping ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_GRAY); ColorConvertOp op = new ColorConvertOp(cs, null); op.filter(img, img); // gray scaling the image // Tesseract1 instance = new Tesseract1(); // JNA Direct Mapping try { String result = instance.doOCR(img); System.out.println("hahahaha"); System.out.println("The result is: " + result); } catch (TesseractException e) { System.out.println("error:" + e); } } catch (IOException ex) { Logger.getLogger(JavaApplication10.class.getName()).log(Level.SEVERE, null, ex); } } }

This is what I found please feel free to correct me if I'm wrong anywhere.

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