Javascript隐写术:在图像中隐藏图像

// 示例代码：使用LSB隐写术嵌入图像
function embedImage(originalImage, secretImage) {
    const canvas = document.createElement('canvas');
    const ctx = canvas.getContext('2d');
    canvas.width = originalImage.width;
    canvas.height = originalImage.height;

    ctx.drawImage(originalImage, 0, 0);
    const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
    const data = imageData.data;

    // 嵌入secretImage的像素数据
    for (let i = 0; i < secretImage.width * secretImage.height * 4; i += 4) {
        const x = i / 4 % secretImage.width;
        const y = Math.floor(i / 4 / secretImage.width);
        const index = (y * canvas.width + x) * 4;
        data[index] = (data[index] & 0xFE) | ((secretImage.data[i] >> 7) & 0x01);
        data[index + 1] = (data[index + 1] & 0xFE) | ((secretImage.data[i + 1] >> 7) & 0x01);
        data[index + 2] = (data[index + 2] & 0xFE) | ((secretImage.data[i + 2] >> 7) & 0x01);
        data[index + 3] = (data[index + 3] & 0xFE) | ((secretImage.data[i + 3] >> 7) & 0x01);
    }

    ctx.putImageData(imageData, 0, 0);
    return canvas.toDataURL();
}

// 示例代码：提取嵌入的图像
function extractImage(stegoImage) {
    const canvas = document.createElement('canvas');
    const ctx = canvas.getContext('2d');
    canvas.width = stegoImage.width;
    canvas.height = stegoImage.height;

    ctx.drawImage(stegoImage, 0, 0);
    const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
    const data = imageData.data;
    const secretImageData = new Uint8ClampedArray(canvas.width * canvas.height * 4);

    for (let i = 0; i < data.length; i += 4) {
        secretImageData[i] = (data[i] & 0x01) << 7;
        secretImageData[i + 1] = (data[i + 1] & 0x01) << 7;
        secretImageData[i + 2] = (data[i + 2] & 0x01) << 7;
        secretImageData[i + 3] = (data[i + 3] & 0x01) << 7;
    }

    const secretCanvas = document.createElement('canvas');
    const secretCtx = secretCanvas.getContext('2d');
    secretCanvas.width = canvas.width;
    secretCanvas.height = canvas.height;
    secretCtx.putImageData(new ImageData(secretImageData, canvas.width, canvas.height), 0, 0);
    return secretCanvas.toDataURL();
}