Display brightness histogram on JavaFX LineChart

The java.awt.Color.RGBtoHSB(int r, int g, int b, float[] hsbvals) method converts RGB components to an equivalent set of values for hue, saturation, and brightness that are the three components of the HSB model. We can easy modify last post "Display image's Histogram on JavaFX LineChart" to display brightness histogram.


remark: In the video, photos from http://www.ultimate-photo-tips.com/histogram-examples.html are used as sample to generate histogram.

Example code:

package javafx_imagehistogram;

import java.awt.Color;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.scene.Scene;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.TextField;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.image.PixelReader;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 * @web http://java-buddy.blogspot.com
 */
public class JavaFX_ImageHistogram extends Application {

    String defaultImage = "http://goo.gl/kYEQl";

    @Override
    public void start(Stage primaryStage) {

        Label labelInfo = new Label();
        labelInfo.setText(
                "java.version: " + System.getProperty("java.version") + "\n"
                + "javafx.runtime.version: " + System.getProperty("javafx.runtime.version")
        );

        TextField textSrc = new TextField();
        textSrc.setText(defaultImage);
        Button btnDo = new Button("Do Histogram");
        ImageView imageView = new ImageView();

        final CategoryAxis xAxis = new CategoryAxis();
        final NumberAxis yAxis = new NumberAxis();
        final LineChart<String, Number> chartHistogram
                = new LineChart<>(xAxis, yAxis);
        chartHistogram.setCreateSymbols(false);
        
        final CategoryAxis xAxis_brightness = new CategoryAxis();
        final NumberAxis yAxis_brightness = new NumberAxis();
        final LineChart<String, Number> brightnessHistogram
                = new LineChart<>(xAxis_brightness, yAxis_brightness);
        brightnessHistogram.setCreateSymbols(false);
        
        VBox vBoxHistogram = new VBox();
        vBoxHistogram.getChildren().addAll(chartHistogram, brightnessHistogram);
        ScrollPane scrollPane = new ScrollPane();
        scrollPane.setContent(vBoxHistogram);

        btnDo.setOnAction((ActionEvent event) -> {

            String imageSrc = textSrc.getText();
            Image image = new Image(imageSrc);
            imageView.setImage(image);
            chartHistogram.getData().clear();
            brightnessHistogram.getData().clear();

            ImageHistogram imageHistogram = new ImageHistogram(image);
            if(imageHistogram.isSuccess()){
                chartHistogram.getData().addAll(
                    //imageHistogram.getSeriesAlpha(),
                    imageHistogram.getSeriesRed(),
                    imageHistogram.getSeriesGreen(),
                    imageHistogram.getSeriesBlue());
                
                brightnessHistogram.getData().add(
                    imageHistogram.getSeriesBrightness());
            }
        });

        HBox hBox = new HBox();
        hBox.getChildren().addAll(imageView, scrollPane);

        VBox vBox = new VBox();
        vBox.getChildren().addAll(labelInfo, textSrc, btnDo, hBox);

        StackPane root = new StackPane();
        root.getChildren().add(vBox);

        Scene scene = new Scene(root, 1000, 500);

        primaryStage.setTitle("java-buddy.blogspot.com");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

    class ImageHistogram {

        private Image image;

        private long alpha[] = new long[256];
        private long red[] = new long[256];
        private long green[] = new long[256];
        private long blue[] = new long[256];
        
        private long brightness[] = new long[256];

        XYChart.Series seriesAlpha;
        XYChart.Series seriesRed;
        XYChart.Series seriesGreen;
        XYChart.Series seriesBlue;
        
        XYChart.Series seriesBrightness;

        private boolean success;

        ImageHistogram(Image src) {
            image = src;
            success = false;

            //init
            for (int i = 0; i < 256; i++) {
                alpha[i] = red[i] = green[i] = blue[i] = 0;
                brightness[i] = 0;
            }

            PixelReader pixelReader = image.getPixelReader();
            if (pixelReader == null) {
                return;
            }

            //count pixels
            for (int y = 0; y < image.getHeight(); y++) {
                for (int x = 0; x < image.getWidth(); x++) {
                    int argb = pixelReader.getArgb(x, y);
                    int a = (0xff & (argb >> 24));
                    int r = (0xff & (argb >> 16));
                    int g = (0xff & (argb >> 8));
                    int b = (0xff & argb);

                    alpha[a]++;
                    red[r]++;
                    green[g]++;
                    blue[b]++;
                    
                    //Convert RGB to HSB (or HSV)
                    float[] hsb = new float[3];
                    Color.RGBtoHSB(r, g, b, hsb);
                    brightness[(int)(hsb[2]*255)]++;
                }
            }

            seriesAlpha = new XYChart.Series();
            seriesRed = new XYChart.Series();
            seriesGreen = new XYChart.Series();
            seriesBlue = new XYChart.Series();
            seriesBrightness = new XYChart.Series();
            seriesAlpha.setName("alpha");
            seriesRed.setName("red");
            seriesGreen.setName("green");
            seriesBlue.setName("blue");
            seriesBrightness.setName("Brightness");

            //copy alpha[], red[], green[], blue[], brightness
            //to seriesAlpha, seriesRed, seriesGreen, seriesBlue, seriesBrightness
            for (int i = 0; i < 256; i++) {
                seriesAlpha.getData().add(new XYChart.Data(String.valueOf(i), alpha[i]));
                seriesRed.getData().add(new XYChart.Data(String.valueOf(i), red[i]));
                seriesGreen.getData().add(new XYChart.Data(String.valueOf(i), green[i]));
                seriesBlue.getData().add(new XYChart.Data(String.valueOf(i), blue[i]));
                
                seriesBrightness.getData().add(new XYChart.Data(String.valueOf(i), brightness[i]));
            }

            success = true;
        }

        public boolean isSuccess() {
            return success;
        }

        public XYChart.Series getSeriesAlpha() {
            return seriesAlpha;
        }

        public XYChart.Series getSeriesRed() {
            return seriesRed;
        }

        public XYChart.Series getSeriesGreen() {
            return seriesGreen;
        }

        public XYChart.Series getSeriesBlue() {
            return seriesBlue;
        }
        
        public XYChart.Series getSeriesBrightness() {
            return seriesBrightness;
        }
    }

}

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