Java BufferedImage Trim trimWhiteSpace(BufferedImage img)

Description

Trims the white border around an image.

License

Open Source License

Parameter

Parameter	Description
img	a parameter

Return

a new image, hopefully trimmed.

Declaration

public static BufferedImage trimWhiteSpace(BufferedImage img) 

Method Source Code

//package com.java2s;
/*/*  w w w . j  a v a2s. c o  m*/
 * This file is part of the LIRE project: http://www.semanticmetadata.net/lire
 * LIRE is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * LIRE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with LIRE; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * We kindly ask you to refer the any or one of the following publications in
 * any publication mentioning or employing Lire:
 *
 * Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval ?
 * An Extensible Java CBIR Library. In proceedings of the 16th ACM International
 * Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008
 * URL: http://doi.acm.org/10.1145/1459359.1459577
 *
 * Lux Mathias. Content Based Image Retrieval with LIRE. In proceedings of the
 * 19th ACM International Conference on Multimedia, pp. 735-738, Scottsdale,
 * Arizona, USA, 2011
 * URL: http://dl.acm.org/citation.cfm?id=2072432
 *
 * Mathias Lux, Oge Marques. Visual Information Retrieval using Java and LIRE
 * Morgan & Claypool, 2013
 * URL: http://www.morganclaypool.com/doi/abs/10.2200/S00468ED1V01Y201301ICR025
 *
 * Copyright statement:
 * ====================
 * (c) 2002-2013 by Mathias Lux (mathias@juggle.at)
 *  http://www.semanticmetadata.net/lire, http://www.lire-project.net
 *
 * Updated: 11.07.13 09:32
 */

import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;

public class Main {
    /**
     * Trims the white border around an image.
     *
     * @param img
     * @return a new image, hopefully trimmed.
     */
    public static BufferedImage trimWhiteSpace(BufferedImage img) {
        // idea is to scan lines of an image starting from each side.
        // As soon as a scan line encounters non-white (or non-black) pixels we know there is actual image content.
        WritableRaster raster = getGrayscaleImage(img).getRaster();
        int[] pixels = new int[Math.max(raster.getWidth(), raster.getHeight())];
        int thresholdWhite = 253;
        int trimTop = 0, trimBottom = 0, trimLeft = 0, trimRight = 0;
        boolean white = true;
        while (white) {
            raster.getPixels(0, trimTop, raster.getWidth(), 1, pixels);
            for (int i = 0; i < raster.getWidth(); i++) {
                if (pixels[i] < thresholdWhite)
                    white = false;
            }
            if (white) {
                trimTop++;
            }
        }
        // bottom:
        white = true;
        while (white) {
            raster.getPixels(0, raster.getHeight() - 1 - trimBottom, raster.getWidth(), 1, pixels);
            for (int i = 0; i < raster.getWidth(); i++) {
                if (pixels[i] < thresholdWhite)
                    white = false;
            }
            if (white) {
                trimBottom++;
            }
        }
        // left:
        white = true;
        while (white) {
            raster.getPixels(trimLeft, 0, 1, raster.getHeight(), pixels);
            for (int i = 0; i < raster.getHeight(); i++) {
                if (pixels[i] < thresholdWhite)
                    white = false;
            }
            if (white) {
                trimLeft++;
            }
        }
        // left:
        white = true;
        while (white) {
            raster.getPixels(raster.getWidth() - 1 - trimRight, 0, 1, raster.getHeight(), pixels);
            for (int i = 0; i < raster.getHeight(); i++) {
                if (pixels[i] < thresholdWhite)
                    white = false;
            }
            if (white) {
                trimRight++;
            }
        }
        //        System.out.println("trimTop = " + trimTop);
        //        System.out.println("trimBottom = " + trimBottom);
        //        System.out.println("trimLeft = " + trimLeft);
        //        System.out.println("trimRight = " + trimRight);
        BufferedImage result = new BufferedImage(raster.getWidth() - (trimLeft + trimRight),
                raster.getHeight() - (trimTop + trimBottom), BufferedImage.TYPE_INT_RGB);
        result.getGraphics().drawImage(img, 0, 0, result.getWidth(), result.getHeight(), trimLeft, trimTop,
                img.getWidth() - trimRight, img.getHeight() - trimBottom, null);
        return result;
    }

    /**
     * Converts an image to grey. Use instead of color conversion op, which yields strange results.
     *
     * @param image
     */
    public static BufferedImage getGrayscaleImage(BufferedImage image) {
        BufferedImage result = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
        result.getGraphics().drawImage(image, 0, 0, null);
        return result;
    }
}

Related

1. trimImageVerticallyHelper(BufferedImage image, int maxToTrim)
2. trimImg(BufferedImage img, Color backgroundColor)
3. trimLockdown(BufferedImage Img, int y1)
4. trimLockup(BufferedImage Img)
5. trimmedImage(BufferedImage source)