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Using Tesseract OCR, convert an image into the string of letters and words found in the image.
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| package xyz.hiddengames.core; | |
| import net.sourceforge.tess4j.Tesseract; | |
| import javax.imageio.ImageIO; | |
| import java.awt.*; | |
| import java.awt.image.BufferedImage; | |
| import java.io.File; | |
| import java.io.IOException; | |
| // Requires Tesseract: https://mvnrepository.com/artifact/net.sourceforge.tess4j/tess4j/4.5.1 | |
| // Requires Tesseract trained data: https://github.com/tesseract-ocr/tessdata_best | |
| // Crop image method from: https://stackoverflow.com/questions/2386064/how-do-i-crop-an-image-in-java | |
| // Resize image method from: https://www.codejava.net/java-se/graphics/how-to-resize-images-in-java | |
| // Invert image method from: https://dyclassroom.com/image-processing-project/how-to-convert-a-color-image-into-negative | |
| // Read image method from: https://www.geeksforgeeks.org/tesseract-ocr-with-java-with-examples/ | |
| // Usage: | |
| // ImageReader.cropImage("src/test/resources/516.jpg", "src/test/resources/515-1.jpg", new Rectangle(20, 150, 245, 475)); | |
| // ImageReader.invertImage("src/test/resources/515-1.jpg", "src/test/resources/515-2.jpg"); | |
| // ImageReader.resizeImage("src/test/resources/515-2.jpg", "src/test/resources/515-3.jpg", 3.8); | |
| // System.out.println(ImageReader.readImage("src/test/resources/515-3.jpg")); | |
| public class ImageReader { | |
| private static String getFormatName(String outputPath) { | |
| // Extracts extension of output file. | |
| return outputPath.substring(outputPath.lastIndexOf(".") + 1); | |
| } | |
| public static void cropImage(String inputImagePath, String outputImagePath, Rectangle rect) { | |
| try { | |
| File inputFile = new File(inputImagePath); | |
| BufferedImage dest = ImageIO.read(inputFile).getSubimage(rect.x, rect.y, rect.width, rect.height); | |
| ImageIO.write(dest, getFormatName(outputImagePath), new File(outputImagePath)); | |
| } catch (Exception e) { e.printStackTrace(); } | |
| } | |
| /** | |
| * Resizes an image to a absolute width and height (the image may not be | |
| * proportional) | |
| * | |
| * @param inputImagePath Path of the original image | |
| * @param outputImagePath Path to save the resized image | |
| * @param scaledWidth absolute width in pixels | |
| * @param scaledHeight absolute height in pixels | |
| */ | |
| public static void resizeImage(String inputImagePath, String outputImagePath, int scaledWidth, int scaledHeight) { | |
| try { | |
| // Reads input image. | |
| File inputFile = new File(inputImagePath); | |
| BufferedImage inputImage = ImageIO.read(inputFile); | |
| // Creates output image. | |
| BufferedImage outputImage = new BufferedImage(scaledWidth, scaledHeight, inputImage.getType()); | |
| // Scales the input image to the output image. | |
| Graphics2D g2d = outputImage.createGraphics(); | |
| g2d.drawImage(inputImage, 0, 0, scaledWidth, scaledHeight, null); | |
| g2d.dispose(); | |
| // Writes to output file. | |
| ImageIO.write(outputImage, getFormatName(outputImagePath), new File(outputImagePath)); | |
| } catch (Exception e) { e.printStackTrace(); } | |
| } | |
| /** | |
| * Resizes an image by a percentage of original size (proportional). | |
| * | |
| * @param inputImagePath Path of the original image | |
| * @param outputImagePath Path to save the resized image | |
| * @param percent a double number specifies percentage of the output image | |
| * over the input image. | |
| */ | |
| public static void resizeImage(String inputImagePath, String outputImagePath, double percent) { | |
| try { | |
| File inputFile = new File(inputImagePath); | |
| BufferedImage inputImage = ImageIO.read(inputFile); | |
| int scaledWidth = (int) (inputImage.getWidth() * percent); | |
| int scaledHeight = (int) (inputImage.getHeight() * percent); | |
| resizeImage(inputImagePath, outputImagePath, scaledWidth, scaledHeight); | |
| } catch (Exception e) { e.printStackTrace(); } | |
| } | |
| public static void invertImage(String inputImagePath, String outputImagePath) { | |
| BufferedImage img = null; | |
| File f = null; | |
| // Read image. | |
| try { | |
| f = new File(inputImagePath); | |
| img = ImageIO.read(f); | |
| } catch (IOException e) { e.printStackTrace(); } | |
| // Get image width and height. | |
| int width = img.getWidth(); | |
| int height = img.getHeight(); | |
| // Convert to negative. | |
| for (int y = 0; y < height; y++) { | |
| for (int x = 0; x < width; x++) { | |
| int p = img.getRGB(x, y); | |
| int a = (p >> 24) & 0xff; | |
| int r = (p >> 16) & 0xff; | |
| int g = (p >> 8) & 0xff; | |
| int b = p & 0xff; | |
| // Subtract RGB from 255. | |
| r = 255 - r; | |
| g = 255 - g; | |
| b = 255 - b; | |
| // Set new RGB value. | |
| p = (a << 24) | (r << 16) | (g << 8) | b; | |
| img.setRGB(x, y, p); | |
| } | |
| } | |
| // Write image to disk. | |
| try { | |
| f = new File(outputImagePath); | |
| ImageIO.write(img, getFormatName(outputImagePath), f); | |
| } catch (IOException e) { e.printStackTrace(); } | |
| } | |
| public static String readImage(String inputImagePath) { | |
| Tesseract tesseract = new Tesseract(); | |
| try { | |
| // The path to your trained data. | |
| tesseract.setDatapath("src/test/resources/tessdata"); | |
| File file = new File(inputImagePath); | |
| if (file.exists()) { | |
| return tesseract.doOCR(file); | |
| } else { | |
| System.out.println("File does not exist."); | |
| } | |
| } catch (Exception e) { e.printStackTrace(); } | |
| return null; | |
| } | |
| } |
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