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：/tesseract-ocr/tesseract
Tess4J的github地址：/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 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 formats = new ArrayList(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 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);
}
