Java Convert a greyscale and sepia version of an image with BufferedImage

Question

I want to read an image and convert and output the original image, a greyscale version, and a sepia version. I am having trouble with the conversion, not very familiar with

Answer 1

Gray scaling is rather easy, sepia not so much. I stole the algorithm off the net...

import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.color.ColorSpace;
import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class ColorAlteration {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }
                try {
                    BufferedImage master = ImageIO.read(new File("C:\\hold\\thumbnails\\_cg_836___Tilting_Windmills___by_Serena_Clearwater.png"));
                    BufferedImage gray = toGrayScale(master);
                    BufferedImage sepia = toSepia(master, 80);

                    JPanel panel = new JPanel(new GridBagLayout());
                    panel.add(new JLabel(new ImageIcon(master)));
                    panel.add(new JLabel(new ImageIcon(gray)));
                    panel.add(new JLabel(new ImageIcon(sepia)));

                    JOptionPane.showMessageDialog(null, panel);

                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        });
    }

    public static BufferedImage toGrayScale(BufferedImage master) {
        BufferedImage gray = new BufferedImage(master.getWidth(), master.getHeight(), BufferedImage.TYPE_INT_ARGB);

        // Automatic converstion....
        ColorConvertOp op = new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null);
        op.filter(master, gray);

        return gray;
    }

    public static BufferedImage toSepia(BufferedImage img, int sepiaIntensity) {

        BufferedImage sepia = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_INT_RGB);
        // Play around with this.  20 works well and was recommended
        //   by another developer. 0 produces black/white image
        int sepiaDepth = 20;

        int w = img.getWidth();
        int h = img.getHeight();

        WritableRaster raster = sepia.getRaster();

        // We need 3 integers (for R,G,B color values) per pixel.
        int[] pixels = new int[w * h * 3];
        img.getRaster().getPixels(0, 0, w, h, pixels);

        //  Process 3 ints at a time for each pixel.  Each pixel has 3 RGB
        //    colors in array
        for (int i = 0; i < pixels.length; i += 3) {
            int r = pixels[i];
            int g = pixels[i + 1];
            int b = pixels[i + 2];

            int gry = (r + g + b) / 3;
            r = g = b = gry;
            r = r + (sepiaDepth * 2);
            g = g + sepiaDepth;

            if (r > 255) {
                r = 255;
            }
            if (g > 255) {
                g = 255;
            }
            if (b > 255) {
                b = 255;
            }

            // Darken blue color to increase sepia effect
            b -= sepiaIntensity;

            // normalize if out of bounds
            if (b < 0) {
                b = 0;
            }
            if (b > 255) {
                b = 255;
            }

            pixels[i] = r;
            pixels[i + 1] = g;
            pixels[i + 2] = b;
        }
        raster.setPixels(0, 0, w, h, pixels);

        return sepia;
    }
}

You can find the original posting for the sepia algorithm here

And because I'm stubborn...I changed the sepia algorithm to work with alpha based images...

public static BufferedImage toSepia(BufferedImage img, int sepiaIntensity) {

    BufferedImage sepia = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_INT_ARGB);
    // Play around with this.  20 works well and was recommended
    //   by another developer. 0 produces black/white image
    int sepiaDepth = 20;

    int w = img.getWidth();
    int h = img.getHeight();

    WritableRaster raster = sepia.getRaster();

    // We need 3 integers (for R,G,B color values) per pixel.
    int[] pixels = new int[w * h * 3];
    img.getRaster().getPixels(0, 0, w, h, pixels);

    for (int x = 0; x < img.getWidth(); x++) {
        for (int y = 0; y < img.getHeight(); y++) {

            int rgb = img.getRGB(x, y);
            Color color = new Color(rgb, true);
            int r = color.getRed();
            int g = color.getGreen();
            int b = color.getBlue();
            int gry = (r + g + b) / 3;

            r = g = b = gry;
            r = r + (sepiaDepth * 2);
            g = g + sepiaDepth;

            if (r > 255) {
                r = 255;
            }
            if (g > 255) {
                g = 255;
            }
            if (b > 255) {
                b = 255;
            }

            // Darken blue color to increase sepia effect
            b -= sepiaIntensity;

            // normalize if out of bounds
            if (b < 0) {
                b = 0;
            }
            if (b > 255) {
                b = 255;
            }

            color = new Color(r, g, b, color.getAlpha());
            sepia.setRGB(x, y, color.getRGB());

        }
    }

    return sepia;
}

Answer 2

I used @@MadProgrammer code to write this code. Which I think it is much more efficient.

1. Using raster data of the image instead of accessing each byte of image. Although it seems it copys the data into pixels array, it is not used in the program.

2. You are calling getRGB each time + getWidth() + getHeight() + getRed(), getGreen() + getBlue().

3. Writing colors directly into your image, I think it is a bottleneck once you write a color using setRGB, you will lose graphic processor benefits. (I read it somewhere, but can't find the link now.)

4. Converting the color back to Color object and getting it back using getRGB().

All I did was using bit-wise operators which it is very fast and then copied the pixel arrays once I was done working with it. Function call is expensive and I avoided them.

However, thanks for the idea, @MadProgrammer.

public static BufferedImage toSepia(BufferedImage image, int sepiaIntensity) {

    int width = image.getWidth();
    int height = image.getHeight();
    int sepiaDepth = 20;

    int[] imagePixels = image.getRGB(0, 0, width, height, null, 0, width);

    for (int i = 0; i < imagePixels.length; i++) {
        int color = imagePixels[i];

        int r = (color >> 16) & 0xff;
        int g = (color >> 8) & 0xff;
        int b = (color) & 0xff;
        int gry = (r + g + b) / 3;

        r = g = b = gry;
        r = r + (sepiaDepth * 2);
        g = g + sepiaDepth;

        if (r > 255) {
            r = 255;
        }
        if (g > 255) {
            g = 255;
        }
        if (b > 255) {
            b = 255;
        }

        // Darken blue color to increase sepia effect
        b -= sepiaIntensity;

        // normalize if out of bounds
        if (b < 0) {
            b = 0;
        }
        if (b > 255) {
            b = 255;
        }

        imagePixels[i] = (color & 0xff000000) + (r << 16) + (g << 8) + b;
    }

    BufferedImage res = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
    res.setRGB(0, 0, width, height, imagePixels, 0, width);
    return res;
}

Answer 3

You can create a filter interface for code reuse.

FilterApp

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class FilterApp {
    public static ClassLoader loader = FilterApp.class.getClassLoader();
    public static String outputDir = "build";

    public static void main(String[] args) {
        try {
            BufferedImage srcImage = loadImage("lobster.jpg");
            File dir = new File(outputDir);

            if (!dir.exists()) {
                dir.mkdirs();
            }

            for (FilterType filter : FilterType.values()) {
                BufferedImage filteredImage = filter.applyFilter(srcImage);
                String filename = String.format("%s/lobster_%s", outputDir, filter.name().toLowerCase());
                writeImage(filteredImage, filename, "jpg");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static BufferedImage loadImage(String filename) throws IOException {
        return ImageIO.read(loader.getResourceAsStream("resources/" + filename));
    }

    private static void writeImage(BufferedImage image, String filename, String ext) throws IOException {
        ImageIO.write(image, ext, new File(filename + '.' + ext));
    }
}

FilterType

import java.awt.image.BufferedImage;

import filter.GreyscaleFilter;
import filter.ImageFilter;
import filter.InvertFilter;
import filter.SepiaFilter;

public enum FilterType {
    GREYSCALE(new GreyscaleFilter()),
    INVERT(new InvertFilter()),
    SEPIA_10(new SepiaFilter(10));

    private ImageFilter filter;

    public ImageFilter getFilter() { return filter; }

    public BufferedImage applyFilter(BufferedImage img) {
        return this.filter.apply(img);
    }

    private FilterType(ImageFilter filter) {
        this.filter = filter;
    }
}

ImageFilter

package filter;

import java.awt.image.BufferedImage;

/** Common Interface for different filters. */ 
public interface ImageFilter {
    public BufferedImage apply(BufferedImage img);
}

GreyscaleFilter

package filter;

import java.awt.color.ColorSpace;
import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;

public class GreyscaleFilter implements ImageFilter {
    @Override
    public BufferedImage apply(BufferedImage img) {
        BufferedImage result = new BufferedImage(img.getWidth(), img.getHeight(), img.getType());
        ColorConvertOp op = new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null);

        op.filter(img, result);

        return result;
    }
}

InvertFilter

package filter;

import java.awt.Color;
import java.awt.image.BufferedImage;

public class InvertFilter implements ImageFilter {
    @Override
    public BufferedImage apply(BufferedImage img) {
        BufferedImage result = new BufferedImage(img.getWidth(), img.getHeight(), img.getType());

        for (int x = 0; x < img.getWidth(); x++) {
            for (int y = 0; y < img.getHeight(); y++) {
                int rgb = img.getRGB(x, y);
                Color color = new Color(rgb, true);
                int r = 255 - color.getRed();
                int g = 255 - color.getGreen();
                int b = 255 - color.getBlue();

                color = new Color(r, g, b, color.getAlpha());
                result.setRGB(x, y, color.getRGB());
            }
        }

        return result;
    }
}

SepiaFilter

package filter;

import java.awt.Color;
import java.awt.image.BufferedImage;

// Algorithm obtained from http://stackoverflow.com/questions/21899824
public class SepiaFilter implements ImageFilter {
    private int intensity;

    public void setIntensity(int intensity) { this.intensity = intensity; }
    public int getIntensity() { return intensity; }

    public SepiaFilter(int intensity) {
        this.intensity = intensity;
    }

    @Override
    public BufferedImage apply(BufferedImage img) {
        BufferedImage result = new BufferedImage(img.getWidth(), img.getHeight(), img.getType());
        // Play around with this.
        // 20 works well and was recommended by another developer.
        // 0 produces black/white image
        int sepiaDepth = 20;

        int w = img.getWidth();
        int h = img.getHeight();

        // We need 3 integers (for R,G,B color values) per pixel.
        int[] pixels = new int[w * h * 3];
        img.getRaster().getPixels(0, 0, w, h, pixels);

        for (int x = 0; x < img.getWidth(); x++) {
            for (int y = 0; y < img.getHeight(); y++) {
                int rgb = img.getRGB(x, y);
                Color color = new Color(rgb, true);
                int r = color.getRed();
                int g = color.getGreen();
                int b = color.getBlue();
                int gry = (r + g + b) / 3;

                r = g = b = gry;
                r = r + (sepiaDepth * 2);
                g = g + sepiaDepth;

                if (r > 255) { r = 255; }
                if (g > 255) { g = 255; }
                if (b > 255) { b = 255; }

                // Darken blue color to increase sepia effect
                b -= this.intensity;

                // normalize if out of bounds
                if (b < 0)   { b = 0; }
                if (b > 255) { b = 255; }

                color = new Color(r, g, b, color.getAlpha());
                result.setRGB(x, y, color.getRGB());
            }
        }

        return result;
    }
}

Output

Source Image

Generated Images