DCT数字水印的matlab代码
时间: 2024-02-12 13:54:57 浏览: 35
以下是一个简单的DCT数字水印的matlab代码示例:
```matlab
% 读取图像
I = imread('lena.png');
figure, imshow(I);
% 转换为灰度图像
I = rgb2gray(I);
% 显示灰度图像
figure, imshow(I);
% 设置水印信息
watermark = 'Hello World!';
% 将水印信息转换为二进制串
binaryWatermark = dec2bin(watermark);
% 将二进制串转换为数组
watermarkArray = zeros(1, length(binaryWatermark));
for i = 1:length(binaryWatermark)
watermarkArray(i) = str2double(binaryWatermark(i));
end
% 将水印信息嵌入到DCT系数中
dctCoeffs = dct2(I);
dctCoeffs(1:8, 1:8) = embedWatermark(dctCoeffs(1:8, 1:8), watermarkArray);
% 显示水印图像
watermarkedI = idct2(dctCoeffs);
figure, imshow(watermarkedI);
% 提取水印信息
extractedWatermark = extractWatermark(dctCoeffs(1:8, 1:8));
% 将二进制串转换为字符
extractedWatermark = char(bin2dec(reshape(num2str(extractedWatermark), 8, []).')).';
disp(extractedWatermark);
% 嵌入水印信息的函数
function coeffs = embedWatermark(coeffs, watermark)
% 将水印信息嵌入到DCT系数中
for i = 1:length(watermark)
if watermark(i) == 1
coeffs(i+1) = coeffs(i+1) + 1;
else
coeffs(i+1) = coeffs(i+1) - 1;
end
end
end
% 提取水印信息的函数
function watermark = extractWatermark(coeffs)
% 提取水印信息
watermark = zeros(1, length(coeffs)-1);
for i = 1:length(watermark)
if coeffs(i+1) > coeffs(i)
watermark(i) = 1;
else
watermark(i) = 0;
end
end
end
```
这个示例代码将一个字符串水印嵌入到lena图像的左上角8x8的DCT系数中,并提取出来以验证。请注意,这只是一个简单的示例代码,实际应用中需要更复杂的技术来保证水印的稳健性和隐蔽性。