AutoCrop.java

/*
 *  Copyright 2012 Eric F. Savage, code@efsavage.com
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */

package com.ajah.image;

import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.logging.Logger;

import javax.imageio.ImageIO;

/**
 * Automatically crops extraneous space from an image.
 * 
 * @author <a href="http://efsavage.com">Eric F. Savage</a>, <a
 *         href="mailto:code@efsavage.com">code@efsavage.com</a>.
 */
public class AutoCrop {

	private static Logger log = Logger.getLogger(AutoCrop.class.getName());

	/**
	 * Crops an image based on the value of the top left pixel.
	 * 
	 * @param image
	 *            The image to crop.
	 * @param fuzziness
	 *            The fuzziness allowed for minor deviations (~5 is
	 *            recommended).
	 * @return The new image data, cropped.
	 * @throws IOException
	 *             If the image could not be read.
	 */
	public static BufferedImage autoCrop(final BufferedImage image, final int fuzziness) throws IOException {
		final Color color = new Color(image.getRGB(0, 0));
		boolean stop = false;
		int cropTop = 0;
		for (int y = 0; y < image.getHeight(); y++) {
			for (int x = 0; x < image.getWidth(); x++) {
				if (!ColorUtils.match(color, image.getRGB(x, y), fuzziness)) {
					stop = true;
					break;
				}
			}
			if (stop) {
				if (y > 0) {
					cropTop = y - 1;
				}
				break;
			}
		}

		log.finest("Cropping top " + cropTop + " rows");

		stop = false;
		int cropBot = image.getHeight();
		for (int y = (image.getHeight() - 1); y >= 0; y--) {
			for (int x = 0; x < image.getWidth(); x++) {
				if (!ColorUtils.match(color, image.getRGB(x, y), fuzziness)) {
					stop = true;
					break;
				}
			}
			if (stop) {
				if (y < image.getHeight()) {
					cropBot = y + 1;
				}
				break;
			}
		}

		log.finest("Cropping bottom " + (image.getHeight() - cropBot) + " rows");

		stop = false;
		int cropLeft = 0;
		for (int x = 0; x < image.getWidth(); x++) {
			for (int y = 0; y < image.getHeight(); y++) {
				if (!ColorUtils.match(color, image.getRGB(x, y), fuzziness)) {
					stop = true;
					break;
				}
			}
			if (stop) {
				if (x > 0) {
					cropLeft = x - 1;
				}
				break;
			}
		}

		log.finest("Cropping left " + cropLeft + " rows");

		stop = false;
		int cropRight = 0;
		for (int x = (image.getWidth() - 1); x >= 0; x--) {
			for (int y = 0; y < image.getHeight(); y++) {
				if (!ColorUtils.match(color, image.getRGB(x, y), fuzziness)) {
					stop = true;
					break;
				}
			}
			if (stop) {
				if (x < image.getWidth()) {
					cropRight = x + 1;
				}
				break;
			}
		}

		log.finest("Cropping right " + (image.getWidth() - cropRight) + " rows");

		final BufferedImage cropped = image.getSubimage(cropLeft, cropTop, cropRight - cropLeft, cropBot - cropTop);
		return cropped;
	}

	/**
	 * Crops an image based on the value of the top left pixel.
	 * 
	 * @param data
	 *            The image data.
	 * @param fuzziness
	 *            The fuzziness allowed for minor deviations (~5 is
	 *            recommended).
	 * @return The new image data, cropped.
	 * @throws IOException
	 *             If the image could not be read.
	 */
	public static byte[] autoCrop(final byte[] data, final int fuzziness) throws IOException {
		final BufferedImage image = ImageIO.read(new ByteArrayInputStream(data));
		final BufferedImage cropped = autoCrop(image, fuzziness);
		final ByteArrayOutputStream out = new ByteArrayOutputStream();
		ImageIO.write(cropped, "png", out);
		return out.toByteArray();
	}

}