178H

    import java.awt.image.BufferedImage;
    import java.io.File;
    import java.io.IOException;
    import java.util.regex.Pattern;
    import javax.imageio.ImageIO;

    public class Fractal {

    public static int n;
    public static BufferedImage fractal;
    public static Pattern p;
    public static int threadNumber;
    private static int returnedThreads = 0;
    private static long t = System.nanoTime();

    public static void main(String[] args) throws IOException {
        n = Integer.parseInt(args[0]);
        p = Pattern.compile(args[1]);
        threadNumber = Integer.parseInt(args[2]);
        fractal = new BufferedImage(n, n, BufferedImage.TYPE_INT_RGB);
        for (int i = 0; i < threadNumber; i++) {
            Thread thread = new Thread(new FractalThread(n, i));
            thread.start();
        }
    }

    public static synchronized void writeImage() throws IOException {
        returnedThreads++;
        if(returnedThreads >= threadNumber) {
            long ti = System.nanoTime();
            File f = new File("fractal.png");
            ImageIO.write(fractal, "PNG", f);
            System.out.println("Done in " + (System.nanoTime()-t)/1000000000F + " s");
        }
    }

    }

    import java.io.IOException;
    import java.util.regex.Matcher;

    public class FractalThread implements Runnable {

    private int n;
    private int threads = Fractal.threadNumber;
    private int startingPoint;

    public FractalThread(int n, int startingPoint) {
        this.n = n;
        this.startingPoint = startingPoint;
    }

    @Override
    public void run() {
        for (int i = startingPoint; i < n * n; i += threads) {
            String code = getCode(i);
            Matcher m = Fractal.p.matcher(code);
            float percentage;
            int rgb = 0;
            if (m.find()) {
                String match = m.group(1);
                percentage = match.length()/(float)code.length();
            } else {
                percentage = 1;
                rgb += 255 * 65536 + 255 * 256;
            }
            int blue = (int) (255 * percentage);
            rgb += blue;
            Fractal.fractal.setRGB(i % n, i / n, rgb);
        }
        try {
            Fractal.writeImage();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public String getCode(int pixel) {
        StringBuilder code = new StringBuilder();
        int currentN = n;
        int x = pixel % currentN;
        int y = pixel / currentN;
        while (currentN > 1) {
            if (y >= currentN / 2) {
                if (x >= currentN / 2) {
                    code.append("4");
                    x -= currentN / 2;
                    y -= currentN / 2;
                } else {
                    code.append("3");
                    y -= currentN / 2;
                }
            } else {
                if (x >= currentN / 2) {
                    code.append("1");
                    x -= currentN / 2;
                } else {
                    code.append("2");
                }
            }
            currentN /= 2;
        }
        return code.toString();
    }

    }