Indicates whether a zero bit indicates a black/dark pixel for a monochrome image RenderedImage. - Java 2D Graphics

Java examples for 2D Graphics:BufferedImage Pixel

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Description

Indicates whether a zero bit indicates a black/dark pixel for a monochrome image RenderedImage.

Demo Code

/*/*from   w w  w.ja va2  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.
 */
//package com.java2s;

import java.awt.image.ColorModel;
import java.awt.image.IndexColorModel;
import java.awt.image.RenderedImage;

public class Main {
    /**
     * Indicates whether a zero bit indicates a black/dark pixel for a
     * monochrome image.
     * 
     * @param img
     *            the image (must be 1 bit monochrome)
     * @return true if a zero bit indicates a black/dark pixel, false for a
     *         white/bright pixel
     */
    public static boolean isZeroBlack(final RenderedImage img) {
        if (!isMonochromeImage(img)) {
            throw new IllegalArgumentException(
                    "Image is not a monochrome image!");
        }
        final IndexColorModel icm = (IndexColorModel) img.getColorModel();
        final int gray0 = convertToGray(icm.getRGB(0));
        final int gray1 = convertToGray(icm.getRGB(1));
        return gray0 < gray1;
    }

    /**
     * Indicates whether an image is a monochrome (1 bit black and white) image.
     * 
     * @param img
     *            the image
     * @return true if it's a monochrome image
     */
    public static boolean isMonochromeImage(final RenderedImage img) {
        return getColorIndexSize(img) == 2;
    }

    /**
     * Convert an RGB color value to a grayscale from 0 to 100.
     * 
     * @param r
     *            the red component
     * @param g
     *            the green component
     * @param b
     *            the blue component
     * @return the gray value
     */
    public static int convertToGray(final int r, final int g, final int b) {
        return (r * 30 + g * 59 + b * 11) / 100;
    }

    /**
     * Convert an RGB color value to a grayscale from 0 to 100.
     * 
     * @param rgb
     *            the RGB value
     * @return the gray value
     */
    public static int convertToGray(final int rgb) {
        final int r = (rgb & 0xFF0000) >> 16;
        final int g = (rgb & 0xFF00) >> 8;
        final int b = rgb & 0xFF;
        return convertToGray(r, g, b);
    }

    /**
     * Returns the size of the color index if the given image has one.
     * 
     * @param img
     *            the image
     * @return the size of the color index or 0 if there's no color index
     */
    public static int getColorIndexSize(final RenderedImage img) {
        final ColorModel cm = img.getColorModel();
        if (cm instanceof IndexColorModel) {
            final IndexColorModel icm = (IndexColorModel) cm;
            return icm.getMapSize();
        } else {
            return 0;
        }
    }
}

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