Compress and save an image to the disk : ImageIO « 2D Graphics « Java Tutorial






/*
 * Copyright (c) JForum Team
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 * with or without modification, are permitted provided 
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 * following  disclaimer.
 * 2)  Redistributions in binary form must reproduce the 
 * above copyright notice, this list of conditions and 
 * the following disclaimer in the documentation and/or 
 * other materials provided with the distribution.
 * 3) Neither the name of "Rafael Steil" nor 
 * the names of its contributors may be used to endorse 
 * or promote products derived from this software without 
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT 
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 * 
 * This file creation date: 21/04/2004 - 19:54:16
 * The JForum Project
 * http://www.jforum.net
 */

import java.awt.Dimension;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.PixelGrabber;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.Locale;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream;


/**
 * Utilities methods for image manipulation. It does not support writting of GIF images, but it can
 * read from. GIF images will be saved as PNG.
 * 
 * @author Rafael Steil
 * @version $Id: ImageUtils.java,v 1.23 2007/09/09 01:05:22 rafaelsteil Exp $
 */
public class ImageUtils
{
  public static final int IMAGE_UNKNOWN = -1;
  public static final int IMAGE_JPEG = 0;
  public static final int IMAGE_PNG = 1;
  public static final int IMAGE_GIF = 2;

  /**
   * Resizes an image
   * 
   * @param imgName The image name to resize. Must be the complet path to the file
   * @param type int
   * @param maxWidth The image's max width
   * @param maxHeight The image's max height
   * @return A resized <code>BufferedImage</code>
   */
  public static BufferedImage resizeImage(String imgName, int type, int maxWidth, int maxHeight)
  {
    try {
      return resizeImage(ImageIO.read(new File(imgName)), type, maxWidth, maxHeight);
    }
    catch (IOException e) {
      e.printStackTrace();
    }
  }

  /**
   * Resizes an image.
   * 
   * @param image
   *            The image to resize
   * @param maxWidth
   *            The image's max width
   * @param maxHeight
   *            The image's max height
   * @return A resized <code>BufferedImage</code>
   * @param type
   *            int
   */
  public static BufferedImage resizeImage(BufferedImage image, int type, int maxWidth, int maxHeight)
  {
    Dimension largestDimension = new Dimension(maxWidth, maxHeight);

    // Original size
    int imageWidth = image.getWidth(null);
    int imageHeight = image.getHeight(null);

    float aspectRatio = (float) imageWidth / imageHeight;

    if (imageWidth > maxWidth || imageHeight > maxHeight) {
      if ((float) largestDimension.width / largestDimension.height > aspectRatio) {
        largestDimension.width = (int) Math.ceil(largestDimension.height * aspectRatio);
      }
      else {
        largestDimension.height = (int) Math.ceil(largestDimension.width / aspectRatio);
      }

      imageWidth = largestDimension.width;
      imageHeight = largestDimension.height;
    }

    return createHeadlessSmoothBufferedImage(image, type, imageWidth, imageHeight);
  }

  /**
   * Saves an image to the disk.
   * 
   * @param image  The image to save
   * @param toFileName The filename to use
   * @param type The image type. Use <code>ImageUtils.IMAGE_JPEG</code> to save as JPEG images,
   *  or <code>ImageUtils.IMAGE_PNG</code> to save as PNG.
   * @return <code>false</code> if no appropriate writer is found
   */
  public static boolean saveImage(BufferedImage image, String toFileName, int type)
  {
    try {
      return ImageIO.write(image, type == IMAGE_JPEG ? "jpg" : "png", new File(toFileName));
    }
    catch (IOException e) {
      e.printStackTrace();
    }
  }

  /**
   * Compress and save an image to the disk. Currently this method only supports JPEG images.
   * 
   * @param image The image to save
   * @param toFileName The filename to use
   * @param type The image type. Use <code>ImageUtils.IMAGE_JPEG</code> to save as JPEG images,
   * or <code>ImageUtils.IMAGE_PNG</code> to save as PNG.
   */
  public static void saveCompressedImage(BufferedImage image, String toFileName, int type)
  {
    try {
      if (type == IMAGE_PNG) {
        throw new UnsupportedOperationException("PNG compression not implemented");
      }

      Iterator iter = ImageIO.getImageWritersByFormatName("jpg");
      ImageWriter writer;
      writer = (ImageWriter) iter.next();

      ImageOutputStream ios = ImageIO.createImageOutputStream(new File(toFileName));
      writer.setOutput(ios);

      ImageWriteParam iwparam = new JPEGImageWriteParam(Locale.getDefault());

      iwparam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
      iwparam.setCompressionQuality(0.7F);

      writer.write(null, new IIOImage(image, null, null), iwparam);

      ios.flush();
      writer.dispose();
      ios.close();
    }
    catch (IOException e) {
      e.printStackTrace();
    }
  }

  /**
   * Creates a <code>BufferedImage</code> from an <code>Image</code>. This method can
   * function on a completely headless system. This especially includes Linux and Unix systems
   * that do not have the X11 libraries installed, which are required for the AWT subsystem to
   * operate. This method uses nearest neighbor approximation, so it's quite fast. Unfortunately,
   * the result is nowhere near as nice looking as the createHeadlessSmoothBufferedImage method.
   * 
   * @param image  The image to convert
   * @param w The desired image width
   * @param h The desired image height
   * @return The converted image
   * @param type int
   */
  public static BufferedImage createHeadlessBufferedImage(BufferedImage image, int type, int width, int height)
  {
    if (type == ImageUtils.IMAGE_PNG && hasAlpha(image)) {
      type = BufferedImage.TYPE_INT_ARGB;
    }
    else {
      type = BufferedImage.TYPE_INT_RGB;
    }

    BufferedImage bi = new BufferedImage(width, height, type);

    for (int y = 0; y < height; y++) {
      for (int x = 0; x < width; x++) {
        bi.setRGB(x, y, image.getRGB(x * image.getWidth() / width, y * image.getHeight() / height));
      }
    }

    return bi;
  }

  /**
   * Creates a <code>BufferedImage</code> from an <code>Image</code>. This method can
   * function on a completely headless system. This especially includes Linux and Unix systems
   * that do not have the X11 libraries installed, which are required for the AWT subsystem to
   * operate. The resulting image will be smoothly scaled using bilinear filtering.
   * 
   * @param source The image to convert
   * @param w The desired image width
   * @param h The desired image height
   * @return The converted image
   * @param type  int
   */
  public static BufferedImage createHeadlessSmoothBufferedImage(BufferedImage source, int type, int width, int height)
  {
    if (type == ImageUtils.IMAGE_PNG && hasAlpha(source)) {
      type = BufferedImage.TYPE_INT_ARGB;
    }
    else {
      type = BufferedImage.TYPE_INT_RGB;
    }

    BufferedImage dest = new BufferedImage(width, height, type);

    int sourcex;
    int sourcey;

    double scalex = (double) width / source.getWidth();
    double scaley = (double) height / source.getHeight();

    int x1;
    int y1;

    double xdiff;
    double ydiff;

    int rgb;
    int rgb1;
    int rgb2;

    for (int y = 0; y < height; y++) {
      sourcey = y * source.getHeight() / dest.getHeight();
      ydiff = scale(y, scaley) - sourcey;

      for (int x = 0; x < width; x++) {
        sourcex = x * source.getWidth() / dest.getWidth();
        xdiff = scale(x, scalex) - sourcex;

        x1 = Math.min(source.getWidth() - 1, sourcex + 1);
        y1 = Math.min(source.getHeight() - 1, sourcey + 1);

        rgb1 = getRGBInterpolation(source.getRGB(sourcex, sourcey), source.getRGB(x1, sourcey), xdiff);
        rgb2 = getRGBInterpolation(source.getRGB(sourcex, y1), source.getRGB(x1, y1), xdiff);

        rgb = getRGBInterpolation(rgb1, rgb2, ydiff);

        dest.setRGB(x, y, rgb);
      }
    }

    return dest;
  }

  private static double scale(int point, double scale)
  {
    return point / scale;
  }

  private static int getRGBInterpolation(int value1, int value2, double distance)
  {
    int alpha1 = (value1 & 0xFF000000) >>> 24;
    int red1 = (value1 & 0x00FF0000) >> 16;
    int green1 = (value1 & 0x0000FF00) >> 8;
    int blue1 = (value1 & 0x000000FF);

    int alpha2 = (value2 & 0xFF000000) >>> 24;
    int red2 = (value2 & 0x00FF0000) >> 16;
    int green2 = (value2 & 0x0000FF00) >> 8;
    int blue2 = (value2 & 0x000000FF);

    int rgb = ((int) (alpha1 * (1.0 - distance) + alpha2 * distance) << 24)
      | ((int) (red1 * (1.0 - distance) + red2 * distance) << 16)
      | ((int) (green1 * (1.0 - distance) + green2 * distance) << 8)
      | (int) (blue1 * (1.0 - distance) + blue2 * distance);

    return rgb;
  }

  /**
   * Determines if the image has transparent pixels.
   * 
   * @param image The image to check for transparent pixel.s
   * @return <code>true</code> of <code>false</code>, according to the result
   */
  public static boolean hasAlpha(Image image)
  {
    try {
      PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false);
      pg.grabPixels();

      return pg.getColorModel().hasAlpha();
    }
    catch (InterruptedException e) {
      return false;
    }
  }
}








16.33.ImageIO
16.33.1.Use Image.IO to read an image file and display it
16.33.2.Load an Image from a JAR file
16.33.3.Use the getResourceAsStream method
16.33.4.Show ImageIO Info
16.33.5.Add Image IO Read Progress Listener to ImageReader
16.33.6.Get list of unique supported write formats
16.33.7.Get list of unique MIME types that can be read
16.33.8.Get list of unique MIME types that can be written
16.33.9.Get list of unique supported read formats
16.33.10.Returns true if the specified format name can be read
16.33.11.Returns true if the specified format name can be written
16.33.12.Returns true if the specified file extension can be read
16.33.13.Returns true if the specified file extension can be written
16.33.14.Returns true if the specified mime type can be read
16.33.15.Returns true if the specified mime type can be written
16.33.16.Determining the Format of an Image in a File
16.33.17.Detect image type
16.33.18.Read an Image from a file
16.33.19.Read an Image from inputStream
16.33.20.Read an Image from URL
16.33.21.Write Image with different types
16.33.22.Load the image file from a folder or a jar file: use javax.imageio.ImageIO class to read the image file
16.33.23.Detect the file type of the input stream prior to reading the image
16.33.24.Compress and save an image to the disk
16.33.25.Resizes an image
16.33.26.Creates an image compatible with the current display