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Add Images#computePerceptualHash()
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@BalusC
BalusC committed Dec 6, 2024
1 parent 969a637 commit 81a21d1
Showing 1 changed file with 65 additions and 28 deletions.
93 changes: 65 additions & 28 deletions src/main/java/org/omnifaces/utils/image/Images.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,19 +18,22 @@
import static java.awt.image.BufferedImage.TYPE_INT_ARGB;
import static java.awt.image.BufferedImage.TYPE_INT_RGB;
import static java.lang.Math.max;
import static java.util.stream.IntStream.range;
import static javax.imageio.ImageIO.read;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.math.BigInteger;
import java.util.Base64;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Consumer;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.stream.MemoryCacheImageOutputStream;

public final class Images {
Expand All @@ -44,23 +47,23 @@ public static BufferedImage toBufferedImage(byte[] content) throws IOException {
}

public static byte[] toPng(BufferedImage image) throws IOException {
ByteArrayOutputStream output = new ByteArrayOutputStream();
var output = new ByteArrayOutputStream();
ImageIO.write(image, "png", output);
return output.toByteArray();
}

public static byte[] toJpg(BufferedImage image) throws IOException {
// Start with a white layer to have images with an alpha layer handled correctly.
BufferedImage newBufferedImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);
var newBufferedImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);
newBufferedImage.createGraphics().drawImage(image, 0, 0, Color.WHITE, null);

// Manually get the ImageWriter to be able to adjust quality
ImageWriter writer = ImageIO.getImageWritersBySuffix("jpg").next();
ImageWriteParam imageWriterParam = writer.getDefaultWriteParam();
var writer = ImageIO.getImageWritersBySuffix("jpg").next();
var imageWriterParam = writer.getDefaultWriteParam();
imageWriterParam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
imageWriterParam.setCompressionQuality(1f);

ByteArrayOutputStream output = new ByteArrayOutputStream();
var output = new ByteArrayOutputStream();
writer.setOutput(new MemoryCacheImageOutputStream(output));
writer.write(null, new IIOImage(newBufferedImage, null, null), imageWriterParam);
writer.dispose();
Expand All @@ -69,10 +72,10 @@ public static byte[] toJpg(BufferedImage image) throws IOException {
}

public static BufferedImage cropImage(BufferedImage image, int desiredWidth, int desiredHeight) {
boolean cropHorizontally = (image.getWidth() > desiredWidth);
var cropHorizontally = image.getWidth() > desiredWidth;

int x = cropHorizontally ? (image.getWidth() - desiredWidth) / 2 : 0;
int y = cropHorizontally ? 0 : (image.getHeight() - desiredHeight) / 2;
var x = cropHorizontally ? (image.getWidth() - desiredWidth) / 2 : 0;
var y = cropHorizontally ? 0 : (image.getHeight() - desiredHeight) / 2;

return image.getSubimage(x, y, desiredWidth, desiredHeight);
}
Expand All @@ -89,45 +92,79 @@ public static BufferedImage cropImage(BufferedImage image, double desiredAspectR
return cropToSquareImage(image);
}

double currentAspectRatio = image.getWidth() * 1.0 / image.getHeight();
var currentAspectRatio = image.getWidth() * 1.0 / image.getHeight();

if (currentAspectRatio == desiredAspectRatio) {
return image;
}

boolean cropHorizontally = (currentAspectRatio > desiredAspectRatio);

int desiredWidth = cropHorizontally ? (int) (image.getHeight() * desiredAspectRatio) : image.getWidth();
int desiredHeight = cropHorizontally ? image.getHeight() : (int) (image.getWidth() / desiredAspectRatio);

var cropHorizontally = currentAspectRatio > desiredAspectRatio;
var desiredWidth = cropHorizontally ? (int) (image.getHeight() * desiredAspectRatio) : image.getWidth();
var desiredHeight = cropHorizontally ? image.getHeight() : (int) (image.getWidth() / desiredAspectRatio);
return cropImage(image, desiredWidth, desiredHeight);
}

public static BufferedImage cropToSquareImage(BufferedImage image) {
boolean cropHorizontally = (image.getWidth() > image.getHeight());

int desiredSize = cropHorizontally ? image.getHeight() : image.getWidth();

var cropHorizontally = image.getWidth() > image.getHeight();
var desiredSize = cropHorizontally ? image.getHeight() : image.getWidth();
return cropImage(image, desiredSize, desiredSize);
}

public static BufferedImage progressiveBilinearDownscale(BufferedImage image, int desiredWidth, int desiredHeight) {
BufferedImage rescaledImage = image;
var rescaledImage = image;

while (rescaledImage.getWidth() > desiredWidth || rescaledImage.getHeight() > desiredHeight) {
int nextWidth = max(rescaledImage.getWidth() / 2, desiredWidth);
int nextHeight = max(rescaledImage.getHeight() / 2, desiredHeight);

BufferedImage nextScaledImage = new BufferedImage(nextWidth, nextHeight, image.getTransparency() == OPAQUE ? TYPE_INT_RGB : TYPE_INT_ARGB);
Graphics2D graphics = nextScaledImage.createGraphics();
var nextWidth = max(rescaledImage.getWidth() / 2, desiredWidth);
var nextHeight = max(rescaledImage.getHeight() / 2, desiredHeight);
var nextScaledImage = new BufferedImage(nextWidth, nextHeight, image.getTransparency() == OPAQUE ? TYPE_INT_RGB : TYPE_INT_ARGB);
var graphics = nextScaledImage.createGraphics();
graphics.setRenderingHint(KEY_INTERPOLATION, VALUE_INTERPOLATION_BILINEAR);
graphics.drawImage(rescaledImage, 0, 0, nextWidth, nextHeight, null);
graphics.dispose();

rescaledImage = nextScaledImage;
}

return rescaledImage;
}

}
public static BufferedImage grayscale(BufferedImage image) {
var grayscale = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
var g = grayscale.getGraphics();
g.drawImage(image, 0, 0, null);
g.dispose();
return grayscale;
}

/**
* https://apiumhub.com/tech-blog-barcelona/introduction-perceptual-hashes-measuring-similarity/
*/
public static String computePerceptualHash(BufferedImage image, int size, int base) {
if (size < 8 || size > 32) {
throw new IllegalArgumentException("size " + size + " must be between 8 and 32");
}
if (base != 2 && base != 10 && base != 16 && base != 32 && base != 36 && base != 64) {
throw new IllegalArgumentException("base " + base + " must be 2, 10, 16, 32, 36 or 64");
}

var grayscale = grayscale(progressiveBilinearDownscale(image, size, size));
Consumer<Consumer<Integer>> forEachPixel = perPixel -> range(0, size).forEach(x -> range(0, size).forEach(y -> perPixel.accept(grayscale.getRGB(x, y) & 0xFF)));
var totalPixelValue = new AtomicInteger();
forEachPixel.accept(pixel -> totalPixelValue.addAndGet(pixel));
var averagePixelValue = totalPixelValue.get() / (size * size);
var perceptualHash = new StringBuilder();
forEachPixel.accept(pixel -> perceptualHash.append(pixel > averagePixelValue ? "1" : "0"));
var hash = perceptualHash.toString();

if (base == 2) {
return hash;
} else {
var integer = new BigInteger(hash, 2);

if (base == 64) {
return Base64.getEncoder().encodeToString(integer.toByteArray());
} else {
return integer.toString(base);
}
}
}
}

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