Java BufferedImage Operation palettize(BufferedImage img, int maxEntries)

Description

Convert an image to a palletized one.

License

Apache License

Declaration

public static BufferedImage palettize(BufferedImage img, int maxEntries) 

Method Source Code

//package com.java2s;
/*// w w  w . ja  v a  2  s.c  o  m
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.
 */

import com.google.common.collect.Maps;

import java.awt.image.BufferedImage;

import java.awt.image.DataBuffer;
import java.awt.image.IndexColorModel;
import java.awt.image.WritableRaster;
import java.util.Map;

public class Main {
    /**
     * Convert an image to a palletized one. Will not create a palette above a fixed
     * number of entries
     */
    public static BufferedImage palettize(BufferedImage img, int maxEntries) {
        // Just because an image has a palette doesnt mean it has a good one
        // so we re-index even if its an IndexColorModel
        int addedCount = 0;
        Map<Integer, Integer> added = Maps.newHashMap();
        for (int y = 0; y < img.getHeight(); y++) {
            for (int x = 0; x < img.getWidth(); x++) {
                if (!added.containsKey(img.getRGB(x, y))) {
                    added.put(img.getRGB(x, y), addedCount++);
                }
                if (added.size() > maxEntries) {
                    // Bail if palette becomes too large
                    return null;
                }
            }
        }
        int[] cmap = new int[added.size()];
        for (int c : added.keySet()) {
            cmap[added.get(c)] = c;
        }

        int bitCount = 1;
        while (added.size() >> bitCount != 0) {
            bitCount *= 2;
        }

        IndexColorModel icm = new IndexColorModel(bitCount, added.size(),
                cmap, 0, DataBuffer.TYPE_BYTE, null);

        // Check if generated palette matched original
        if (img.getColorModel() instanceof IndexColorModel) {
            IndexColorModel originalModel = (IndexColorModel) img
                    .getColorModel();
            if (originalModel.getPixelSize() == icm.getPixelSize()
                    && originalModel.getMapSize() == icm.getMapSize()) {
                // Old model already had efficient palette
                return null;
            }
        }

        // Be careful to assign correctly assign byte packing method based on pixel size
        BufferedImage dst = new BufferedImage(img.getWidth(),
                img.getHeight(),
                icm.getPixelSize() < 8 ? BufferedImage.TYPE_BYTE_BINARY
                        : BufferedImage.TYPE_BYTE_INDEXED, icm);

        WritableRaster wr = dst.getRaster();
        for (int y = 0; y < dst.getHeight(); y++) {
            for (int x = 0; x < dst.getWidth(); x++) {
                wr.setSample(x, y, 0, added.get(img.getRGB(x, y)));
            }
        }
        return dst;
    }
}

Related

1. optimizeImage(BufferedImage image)
2. otsuTreshold(BufferedImage original)
3. output(BufferedImage image, OutputStream out)
4. outPutImage(BufferedImage bufferedimage, String targetPath)
5. paletteSwapARGB8(Color[] colorSet, Color clearToColorRequested, BufferedImage argbMappedBufferedImage)
6. performRescaleOperation(BufferedImage image, float scale, float offset)
7. prepareModel(BufferedImage model)
8. recolor(BufferedImage img, int newColor)
9. recolor(BufferedImage src, Color sc)