JAVA使用Tess4J进行ocr识别

Tess4J是对Tesseract OCR API.的Java JNA 封装。使java能够通过调用Tess4J的API来使用Tesseract OCR。支持的格式：TIFF,JPEG,GIF,PNG,BMP,JPEG,and PDF
Tesseract 的github地址：https://github.com/tesseract-ocr/tesseract
Tess4J的github地址：https://github.com/nguyenq/tess4j

Tess4J API 提供的功能：
1、直接识别支持的文件
2、识别图片流
3、识别图片的某块区域
4、将识别结果保存为 TEXT/ HOCR/ PDF/ UNLV/ BOX
5、通过设置取词的等级，提取识别出来的文字
6、获得每一个识别区域的具体坐标范围
7、调整倾斜的图片
8、裁剪图片
9、调整图片分辨率
10、从粘贴板获得图像
11、克隆一个图像（目的：创建一份一模一样的图片，与原图在操作修改上，不相 互影响）
12、图片转换为二进制、黑白图像、灰度图像
13、反转图片颜色
demo.java:

    /**
     * Test of doOCR method, of class Tesseract.
     * 根据图片文件进行识别
     * @throws Exception while processing image.
     */
    @Test
    public void testDoOCR_File() throws Exception {
        logger.info("doOCR on a jpg image");
        File imageFile = new File(this.testResourcesDataPath, "ocr.png");
        //set language
        instance.setDatapath(testResourcesLanguagePath);
        instance.setLanguage("chi_sim");
        String result = instance.doOCR(imageFile);
        logger.info(result);
    }

    /**
     * Test of doOCR method, of class Tesseract.
     * 根据图片流进行识别
     * @throws Exception while processing image.
     */
    @Test
    public void testDoOCR_BufferedImage() throws Exception {
        logger.info("doOCR on a buffered image of a PNG");
        File imageFile = new File(this.testResourcesDataPath, "ocr.png");
        BufferedImage bi = ImageIO.read(imageFile);

        //set language
        instance.setDatapath(testResourcesLanguagePath);
        instance.setLanguage("chi_sim");

        String result = instance.doOCR(bi);
        logger.info(result);
    }

    /**
     * Test of getSegmentedRegions method, of class Tesseract.
     * 得到每一个划分区域的具体坐标
     * @throws java.lang.Exception
     */
    @Test
    public void testGetSegmentedRegions() throws Exception {
        logger.info("getSegmentedRegions at given TessPageIteratorLevel");
        File imageFile = new File(testResourcesDataPath, "ocr.png");
        BufferedImage bi = ImageIO.read(imageFile);
        int level = TessPageIteratorLevel.RIL_SYMBOL;
        logger.info("PageIteratorLevel: " + Utils.getConstantName(level, TessPageIteratorLevel.class));
        List<Rectangle> result = instance.getSegmentedRegions(bi, level);
        for (int i = 0; i < result.size(); i++) {
            Rectangle rect = result.get(i);
            logger.info(String.format("Box[%d]: x=%d, y=%d, w=%d, h=%d", i, rect.x, rect.y, rect.width, rect.height));
        }

        assertTrue(result.size() > 0);
    }


    /**
     * Test of doOCR method, of class Tesseract.
     * 根据定义坐标范围进行识别
     * @throws Exception while processing image.
     */
    @Test
    public void testDoOCR_File_Rectangle() throws Exception {
        logger.info("doOCR on a BMP image with bounding rectangle");
        File imageFile = new File(this.testResourcesDataPath, "ocr.png");
        //设置语言库
        instance.setDatapath(testResourcesLanguagePath);
        instance.setLanguage("chi_sim");
        //划定区域
        // x,y是以左上角为原点，width和height是以xy为基础
        Rectangle rect = new Rectangle(84, 21, 15, 13);
        String result = instance.doOCR(imageFile, rect);
        logger.info(result);
    }

    /**
     * Test of createDocuments method, of class Tesseract.
     * 存储结果
     * @throws java.lang.Exception
     */
    @Test
    public void testCreateDocuments() throws Exception {
        logger.info("createDocuments for png");
        File imageFile = new File(this.testResourcesDataPath, "ocr.png");
        String outputbase = "target/test-classes/docrenderer-2";
        List<RenderedFormat> formats = new ArrayList<RenderedFormat>(Arrays.asList(RenderedFormat.HOCR, RenderedFormat.TEXT));

        //设置语言库
        instance.setDatapath(testResourcesLanguagePath);
        instance.setLanguage("chi_sim");

        instance.createDocuments(new String[]{imageFile.getPath()}, new String[]{outputbase}, formats);
    }

    /**
     * Test of getWords method, of class Tesseract.
     * 取词方法
     * @throws java.lang.Exception
     */
    @Test
    public void testGetWords() throws Exception {
        logger.info("getWords");
        File imageFile = new File(this.testResourcesDataPath, "ocr.png");

        //设置语言库
        instance.setDatapath(testResourcesLanguagePath);
        instance.setLanguage("chi_sim");

        //按照每个字取词
        int pageIteratorLevel = TessPageIteratorLevel.RIL_SYMBOL;
        logger.info("PageIteratorLevel: " + Utils.getConstantName(pageIteratorLevel, TessPageIteratorLevel.class));
        BufferedImage bi = ImageIO.read(imageFile);
        List<Word> result = instance.getWords(bi, pageIteratorLevel);

        //print the complete result
        for (Word word : result) {
            logger.info(word.toString());
        }
    }

    /**
     * Test of Invalid memory access.
     * 处理倾斜
     * @throws Exception while processing image.
     */
    @Test
    public void testDoOCR_SkewedImage() throws Exception {
        //设置语言库
        instance.setDatapath(testResourcesLanguagePath);
        instance.setLanguage("chi_sim");

        logger.info("doOCR on a skewed PNG image");
        File imageFile = new File(this.testResourcesDataPath, "ocr_skewed.jpg");
        BufferedImage bi = ImageIO.read(imageFile);
        ImageDeskew id = new ImageDeskew(bi);
        double imageSkewAngle = id.getSkewAngle(); // determine skew angle
        if ((imageSkewAngle > MINIMUM_DESKEW_THRESHOLD || imageSkewAngle < -(MINIMUM_DESKEW_THRESHOLD))) {
            bi = ImageHelper.rotateImage(bi, -imageSkewAngle); // deskew image
        }

        String result = instance.doOCR(bi);
        logger.info(result);
    }

Tess4JDemo码云地址：https://gitee.com/zhaohuihbwj/Tess4JDemo