Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
Captcha OCR + Tesseract
public class OCR {
private static final String INPUT = "C:/captcha/ex.png";
private static final String OUTPUT = "C:/captcha/captcha-out.png";
private static final String TESSERACT_BIN = "C:/Program Files/Tesseract-OCR/tesseract.exe";
private static final String TESSERACT_OUTPUT = "C:/captcha/out.txt";
private static final int WHITE = 0x00FFFFFF, BLACK = 0x00000000;
public static void main(String... args) throws Exception {
BufferedImage image = ImageIO.read(new FileInputStream(INPUT));
int average = 0;
for( int row = 0; ++row < image.getHeight(); )
for ( int column = 0; ++column < image.getWidth(); )
average += image.getRGB(column, row) & 0x000000FF;
average /= image.getWidth() * image.getHeight();
for( int row = 0; ++row < image.getHeight(); )
for ( int column = 0; ++column < image.getWidth(); )
if ((image.getRGB(column, row) & 0x000000FF) <= average * .80)
image.setRGB(column, row, BLACK);
else
image.setRGB(column, row, WHITE);
for( int row = 0; ++row < image.getHeight(); )
for ( int column = 0; ++column < image.getWidth(); )
if ((image.getRGB(column, row) & WHITE) == WHITE) {
int height = countVerticalWhite(image, column, row);
int width = countHorizontalWhite(image, column, row);
if ((width * height <= 6) || (width == 1) || (height == 1))
image.setRGB(column, row, BLACK);
}
for( int row = 0; ++row < image.getHeight(); )
for ( int column = 0; ++column < image.getWidth(); )
if ((image.getRGB(column, row) & WHITE) != WHITE)
if (countBlackNeighbors(image, column, row) <= 3)
image.setRGB(column, row, WHITE);
ImageIO.write(image, "png", new File(OUTPUT));
Process tesseractProc = Runtime.getRuntime().exec(TESSERACT_BIN + " " + OUTPUT + " " + TESSERACT_OUTPUT + " nobatch letters");
tesseractProc.waitFor();
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(TESSERACT_OUTPUT + ".txt")));
System.out.println("CAPTCHA: " + reader.readLine());
reader.close();
}
private static int countVerticalWhite(BufferedImage image, int x, int y) {
return (countAboveWhite(image, x, y) + countBelowWhite(image, x, y)) + 1;
}
private static int countHorizontalWhite(BufferedImage image, int x, int y) {
return (countLeftWhite(image, x, y) + countRightWhite(image, x, y)) + 1;
}
private static int countLeftWhite(BufferedImage image, int x, int y) {
int leftWhite = 0;
x--;
while (x-- > 0)
if ((image.getRGB(x, y) & WHITE) == WHITE)
leftWhite++;
else
break;
return leftWhite;
}
private static int countRightWhite(BufferedImage image, int x, int y) {
int rightWhite = 0;
x++;
while (x < image.getWidth())
if ((image.getRGB(x++, y) & WHITE) == WHITE)
rightWhite++;
else
break;
return rightWhite;
}
private static int countBlackNeighbors(BufferedImage image, int x, int y) {
int numBlacks = 0;
if (pixelColor(image, x - 1, y) != WHITE)
numBlacks++;
if (pixelColor(image, x - 1, y + 1) != WHITE)
numBlacks++;
if (pixelColor(image, x - 1, y - 1) != WHITE)
numBlacks++;
if (pixelColor(image, x, y + 1) != WHITE)
numBlacks++;
if (pixelColor(image, x, y - 1) != WHITE)
numBlacks++;
if (pixelColor(image, x + 1, y) != WHITE)
numBlacks++;
if (pixelColor(image, x + 1, y + 1) != WHITE)
numBlacks++;
if (pixelColor(image, x + 1, y - 1) != WHITE)
numBlacks++;
return numBlacks;
}
private static int pixelColor(BufferedImage image, int x, int y) {
if (x >= image.getWidth() || x < 0 || y < 0 || y >= image.getHeight())
return WHITE;
return image.getRGB(x, y) & WHITE;
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.