unknowIfGuestInDream · unknowIfGuestInDream · May 2, 2025 · May 2, 2025
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+/*
+ * Copyright (c) 2025 unknowIfGuestInDream.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *     * Neither the name of unknowIfGuestInDream, any associated website, nor the
+ * names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL UNKNOWIFGUESTINDREAM BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.tlcsdm.core.watermark;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.BitSet;
+
+/**
+ * 基于LSB（最低有效位）的暗水印实现.
+ * LSB水印的局限性：
+ * 1. 对图像处理操作（如压缩、缩放、格式转换）敏感
+ * 2. 容易被发现和移除
+ * 3. 适合对图像质量要求不高且不需要强鲁棒性的场景
+ * <p>
+ * 注意事项
+ * 目前看只支持png
+ *
+ * @author unknowIfGuestInDream
+ */
+public class LSBWatermark {
+    /**
+     * 添加暗水印到图片
+     *
+     * @param inputImage    原始图片文件
+     * @param outputImage   输出图片文件
+     * @param watermarkText 水印文本
+     */
+    public static void addTextWatermark(File inputImage, File outputImage, String watermarkText) throws IOException {
+        BufferedImage image = ImageIO.read(inputImage);
+
+        // 将水印文本转换为字节数组
+        byte[] watermarkBytes = watermarkText.getBytes(StandardCharsets.UTF_8);
+
+        // 将字节数组转换为位集合
+        BitSet watermarkBits = BitSet.valueOf(watermarkBytes);
+
+        // 计算需要多少像素来存储水印(每个像素可以存储3位 - RGB各1位)
+        int requiredPixels = (watermarkBytes.length * 8 + 2) / 3;
+
+        // 检查图片是否有足够像素存储水印
+        if (requiredPixels > image.getWidth() * image.getHeight()) {
+            throw new IllegalArgumentException("图片太小，无法容纳水印数据");
+        }
+
+        // 首先写入水印长度(使用前16位)
+        int watermarkLength = watermarkBytes.length;
+        int pixelIndex = 0;
+
+        // 写入水印长度(16位)
+        for (int i = 0; i < 16; i++) {
+            boolean bit = ((watermarkLength >> (15 - i)) & 1) == 1;
+            setNextWatermarkBit(image, pixelIndex++, bit);
+        }
+
+        // 写入水印数据
+        for (int i = 0; i < watermarkBits.size(); i++) {
+            setNextWatermarkBit(image, pixelIndex++, watermarkBits.get(i));
+        }
+
+        // 保存带水印的图片
+        String formatName = outputImage.getName().substring(outputImage.getName().lastIndexOf(".") + 1);
+        ImageIO.write(image, formatName, outputImage);
+    }
+
+    private static void setNextWatermarkBit(BufferedImage image, int bitIndex, boolean bit) {
+        int x = bitIndex % image.getWidth();
+        int y = bitIndex / image.getWidth();
+
+        int rgb = image.getRGB(x, y);
+
+        // 分解RGB分量
+        int r = (rgb >> 16) & 0xFF;
+        int g = (rgb >> 8) & 0xFF;
+        int b = rgb & 0xFF;
+
+        // 根据位索引决定修改哪个通道的最低有效位
+        int channel = bitIndex % 3;
+        switch (channel) {
+            case 0 -> r = (r & 0xFE) | (bit ? 1 : 0);
+            case 1 -> g = (g & 0xFE) | (bit ? 1 : 0);
+            case 2 -> b = (b & 0xFE) | (bit ? 1 : 0);
+        }
+
+        // 重新组合RGB值
+        int newRgb = (r << 16) | (g << 8) | b;
+        image.setRGB(x, y, newRgb);
+    }
+
+    /**
+     * 从图片中提取暗水印
+     *
+     * @param watermarkedImage 带水印的图片文件
+     * @return 提取出的水印文本
+     * @throws IOException 如果读取图片失败
+     */
+    public static String extractTextWatermark(File watermarkedImage) throws IOException {
+        BufferedImage image = ImageIO.read(watermarkedImage);
+
+        // 首先读取水印长度(16位)
+        int watermarkLength = 0;
+        int pixelIndex = 0;
+
+        for (int i = 0; i < 16; i++) {
+            boolean bit = getNextWatermarkBit(image, pixelIndex++);
+            watermarkLength = (watermarkLength << 1) | (bit ? 1 : 0);
+        }
+
+        // 计算需要读取的位数
+        int totalBits = watermarkLength * 8;
+        BitSet watermarkBits = new BitSet(totalBits);
+
+        // 读取水印数据
+        for (int i = 0; i < totalBits; i++) {
+            watermarkBits.set(i, getNextWatermarkBit(image, pixelIndex++));
+        }
+
+        // 将BitSet转换为字节数组
+        byte[] watermarkBytes = watermarkBits.toByteArray();
+
+        // 确保字节数组长度正确
+        if (watermarkBytes.length < watermarkLength) {
+            byte[] correctedBytes = new byte[watermarkLength];
+            System.arraycopy(watermarkBytes, 0, correctedBytes, 0, watermarkBytes.length);
+            watermarkBytes = correctedBytes;
+        } else if (watermarkBytes.length > watermarkLength) {
+            byte[] correctedBytes = new byte[watermarkLength];
+            System.arraycopy(watermarkBytes, 0, correctedBytes, 0, watermarkLength);
+            watermarkBytes = correctedBytes;
+        }
+
+        return new String(watermarkBytes, StandardCharsets.UTF_8);
+    }
+
+    private static boolean getNextWatermarkBit(BufferedImage image, int bitIndex) {
+        int x = bitIndex % image.getWidth();
+        int y = bitIndex / image.getWidth();
+
+        int rgb = image.getRGB(x, y);
+
+        // 根据位索引决定读取哪个通道的最低有效位
+        int channel = bitIndex % 3;
+        return switch (channel) {
+            case 0 -> ((rgb >> 16) & 0x01) == 1;
+            case 1 -> ((rgb >> 8) & 0x01) == 1;
+            case 2 -> (rgb & 0x01) == 1;
+            default -> false;
+        };
+    }
+}
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+/*
+ * Copyright (c) 2025 unknowIfGuestInDream.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *     * Neither the name of unknowIfGuestInDream, any associated website, nor the
+ * names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL UNKNOWIFGUESTINDREAM BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.tlcsdm.core.watermark;
+
+import cn.hutool.core.io.resource.ResourceUtil;
+import cn.hutool.log.StaticLog;
+import org.apache.commons.io.FilenameUtils;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * @author unknowIfGuestInDream
+ */
+class InvisibleWatermarkTest {
+
+    @ParameterizedTest
+    @ValueSource(strings = {"watermark/originBig.jpg", "watermark/originSmall.png"})
+    void lsb(String inputImagePath) throws IOException {
+        File inputImage = new File(ResourceUtil.getResource(inputImagePath).getFile());
+        File parentFile = inputImage.getParentFile();
+        // 添加暗水印
+        File watermarkedImage = new File(parentFile,
+            FilenameUtils.getBaseName(inputImage.getName()) + "_lsb." + FilenameUtils.getExtension(
+                inputImage.getName()));
+        String watermarkText = "Copyright 2025 - Tlcsdm";
+
+        LSBWatermark.addTextWatermark(inputImage, watermarkedImage, watermarkText);
+        StaticLog.info("暗水印添加成功!");
+
+        // 提取暗水印
+        String extractedWatermark = LSBWatermark.extractTextWatermark(watermarkedImage);
+        if ("png".equals(FilenameUtils.getExtension(inputImage.getName()))) {
+            Assertions.assertEquals(watermarkText, extractedWatermark);
+        } else {
+            Assertions.assertNotEquals(watermarkText, extractedWatermark);
+        }
+    }
+
+}