64 lines
1.8 KiB
Java
64 lines
1.8 KiB
Java
import java.awt.image.BufferedImage;
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import java.io.File;
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import java.io.IOException;
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import javax.imageio.ImageIO;
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public enum ImageProcessing {
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;
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public static void main(String[] args) throws IOException {
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BufferedImage img = ImageIO.read(new File("example.png"));
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BufferedImage bwimg = toBlackAndWhite(img);
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ImageIO.write(bwimg, "png", new File("example-bw.png"));
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}
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private static int luminance(int rgb) {
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int r = (rgb >> 16) & 0xFF;
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int g = (rgb >> 8) & 0xFF;
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int b = rgb & 0xFF;
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return (r + b + g) / 3;
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}
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private static BufferedImage toBlackAndWhite(BufferedImage img) {
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int width = img.getWidth();
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int height = img.getHeight();
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int[] histo = computeHistogram(img);
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int median = getMedian(width * height, histo);
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BufferedImage bwimg = new BufferedImage(width, height, img.getType());
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for (int y = 0; y < height; y++) {
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for (int x = 0; x < width; x++) {
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bwimg.setRGB(x, y, luminance(img.getRGB(x, y)) >= median ? 0xFFFFFFFF : 0xFF000000);
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}
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}
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return bwimg;
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}
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private static int[] computeHistogram(BufferedImage img) {
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int width = img.getWidth();
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int height = img.getHeight();
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int[] histo = new int[256];
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for (int y = 0; y < height; y++) {
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for (int x = 0; x < width; x++) {
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histo[luminance(img.getRGB(x, y))]++;
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}
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}
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return histo;
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}
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private static int getMedian(int total, int[] histo) {
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int median = 0;
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int sum = 0;
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for (int i = 0; i < histo.length && sum + histo[i] < total / 2; i++) {
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sum += histo[i];
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median++;
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}
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return median;
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}
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}
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