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• ImageUtil.java

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com.recognition.software.jdeskew.ImageUtil Maven / Gradle / Ivy

/**
 * JDeskew
 */
package com.recognition.software.jdeskew;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;

import net.sourceforge.tess4j.util.LoggHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ImageUtil {

    private static final Logger logger = LoggerFactory.getLogger(new LoggHelper().toString());

    /**
     * Whether the pixel is black.
     * 
     * @param image source image
     * @param x x-coordinate
     * @param y y-coordinate
     * @return true if pixel is black; false, otherwise
     */
    public static boolean isBlack(BufferedImage image, int x, int y) {
        if (image.getType() == BufferedImage.TYPE_BYTE_BINARY) {
            WritableRaster raster = image.getRaster();
            int pixelRGBValue = raster.getSample(x, y, 0);
            return pixelRGBValue == 0;
        }

        int luminanceValue = 140;
        return isBlack(image, x, y, luminanceValue);
    }

    /**
     * Whether the pixel is black.
     * 
     * @param image source image
     * @param x x-coordinate
     * @param y y-coordinate
     * @param luminanceCutOff luminance threshold
     * @return true if pixel is black; false, otherwise
     */
    public static boolean isBlack(BufferedImage image, int x, int y, int luminanceCutOff) {
        int pixelRGBValue;
        int r;
        int g;
        int b;
        double luminance = 0.0;

        // return white on areas outside of image boundaries
        if (x < 0 || y < 0 || x > image.getWidth() || y > image.getHeight()) {
            return false;
        }

        try {
            pixelRGBValue = image.getRGB(x, y);
            r = (pixelRGBValue >> 16) & 0xff;
            g = (pixelRGBValue >> 8) & 0xff;
            b = (pixelRGBValue) & 0xff;
            luminance = (r * 0.299) + (g * 0.587) + (b * 0.114);
        } catch (Exception e) {
            logger.warn("", e);
        }

        return luminance < luminanceCutOff;
    }

    /**
     * Rotates image.
     * 
     * @param image source image
     * @param angle by degrees
     * @param cx x-coordinate of pivot point
     * @param cy y-coordinate of pivot point
     * @return rotated image
     */
    public static BufferedImage rotate(BufferedImage image, double angle, int cx, int cy) {
        int width = image.getWidth(null);
        int height = image.getHeight(null);

        int minX, minY, maxX, maxY;
        minX = minY = maxX = maxY = 0;

        int[] corners = {0, 0, width, 0, width, height, 0, height};

        double theta = Math.toRadians(angle);
        for (int i = 0; i < corners.length; i += 2) {
            int x = (int) (Math.cos(theta) * (corners[i] - cx)
                    - Math.sin(theta) * (corners[i + 1] - cy) + cx);
            int y = (int) (Math.sin(theta) * (corners[i] - cx)
                    + Math.cos(theta) * (corners[i + 1] - cy) + cy);

            if (x > maxX) {
                maxX = x;
            }

            if (x < minX) {
                minX = x;
            }

            if (y > maxY) {
                maxY = y;
            }

            if (y < minY) {
                minY = y;
            }

        }

        cx = (cx - minX);
        cy = (cy - minY);

        BufferedImage bi = new BufferedImage((maxX - minX), (maxY - minY),
                image.getType());
        Graphics2D g2 = bi.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                RenderingHints.VALUE_INTERPOLATION_BICUBIC);

        g2.setBackground(Color.white);
        g2.fillRect(0, 0, bi.getWidth(), bi.getHeight());

        AffineTransform at = new AffineTransform();
        at.rotate(theta, cx, cy);

        g2.setTransform(at);
        g2.drawImage(image, -minX, -minY, null);
        g2.dispose();

        return bi;
    }
}