Question

Can we find which color is dominant in an image using Java, ImageMagick, or JMagick?

Answer 1

in java iterate on each pixel and determine color

import java.awt.image.BufferedImage;
import java.io.File;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;


public class ImageTester {


    public static void main(String args[]) throws Exception {
        File file = new File("C:\\Users\\Andrew\\Desktop\\myImage.gif");
        ImageInputStream is = ImageIO.createImageInputStream(file);
        Iterator iter = ImageIO.getImageReaders(is);

        if (!iter.hasNext())
        {
            System.out.println("Cannot load the specified file "+ file);
            System.exit(1);
        }
        ImageReader imageReader = (ImageReader)iter.next();
        imageReader.setInput(is);

        BufferedImage image = imageReader.read(0);

        int height = image.getHeight();
        int width = image.getWidth();

        Map m = new HashMap();
        for(int i=0; i < width ; i++)
        {
            for(int j=0; j < height ; j++)
            {
                int rgb = image.getRGB(i, j);
                int[] rgbArr = getRGBArr(rgb);                
                // Filter out grays....                
                if (!isGray(rgbArr)) {                
                        Integer counter = (Integer) m.get(rgb);   
                        if (counter == null)
                            counter = 0;
                        counter++;                                
                        m.put(rgb, counter);                
                }                
            }
        }        
        String colourHex = getMostCommonColour(m);
        System.out.println(colourHex);
    }


    public static String getMostCommonColour(Map map) {
        List list = new LinkedList(map.entrySet());
        Collections.sort(list, new Comparator() {
              public int compare(Object o1, Object o2) {
                return ((Comparable) ((Map.Entry) (o1)).getValue())
                  .compareTo(((Map.Entry) (o2)).getValue());
              }
        });    
        Map.Entry me = (Map.Entry )list.get(list.size()-1);
        int[] rgb= getRGBArr((Integer)me.getKey());
        return Integer.toHexString(rgb[0])+" "+Integer.toHexString(rgb[1])+" "+Integer.toHexString(rgb[2]);        
    }    

    public static int[] getRGBArr(int pixel) {
        int alpha = (pixel >> 24) & 0xff;
        int red = (pixel >> 16) & 0xff;
        int green = (pixel >> 8) & 0xff;
        int blue = (pixel) & 0xff;
        return new int[]{red,green,blue};

  }
    public static boolean isGray(int[] rgbArr) {
        int rgDiff = rgbArr[0] - rgbArr[1];
        int rbDiff = rgbArr[0] - rgbArr[2];
        // Filter out black, white and grays...... (tolerance within 10 pixels)
        int tolerance = 10;
        if (rgDiff > tolerance || rgDiff < -tolerance) 
            if (rbDiff > tolerance || rbDiff < -tolerance) { 
                return false;
            }                 
        return true;
    }
}