Aus dem Informatik-Unterricht

Histogramm.java

import java.awt.Color;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

import de.informatics4kids.Picture;

public class Histogramm {

	public static void main(String[] args) {
		Picture pic = new Picture("/home/student/devel/Bildverarbeitung/img/hund.jpg");
		int[][] absoluteCounts = new int[3][256];
		for (int y = 0; y < pic.heightY(); y++) {
			for (int x = 0; x < pic.widthX(); x++) {
				Color pxlCol = pic.getColor(x, y);
				for (int i = 0; i < 3; i++) {
					absoluteCounts[i][getColVal(pxlCol, i)]++;
				}
			}
		}
		for (int i = 0; i < absoluteCounts.length; i++) {
			StringBuilder builder = new StringBuilder();
			for (int j = 0; j < absoluteCounts[i].length; j++) {
				if (j != 0)
					builder.append("\n");
				builder.append(
//						j + "\t" + 
						((double) absoluteCounts[i][j]) / (pic.widthX() * pic.heightY()));
			}
			try {
				Files.writeString(Paths.get("/home/student/", String.valueOf(i) + ".txt"), builder.toString(), StandardOpenOption.CREATE);
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	public static int getColVal(Color c, int valNo) {
		switch (valNo) {
		case 0:
			return c.getRed();
		case 1:
			return c.getGreen();
		case 2:
			return c.getBlue();
		default:
			return c.getAlpha();
		}
	}

}