实现图像的一阶、二阶、三阶、四阶DPCM编码和解码恢复图像的代码

下面是使用MATLAB实现图像的一阶、二阶、三阶、四阶DPCM编码和解码恢复图像的代码：

% 读取图像文件
I = imread('lena.jpg');

% 将图像分为8x8的块
blk_size = 8;
[h, w, d] = size(I);
h_blk_num = floor(h/blk_size);
w_blk_num = floor(w/blk_size);

% 一阶DPCM编码和解码
for i = 1:h_blk_num
    for j = 1:w_blk_num
        blk = double(I(blk_size*(i-1)+1:blk_size*i, blk_size*(j-1)+1:blk_size*j, :));
        diff = blk(:, 2:end, :) - blk(:, 1:end-1, :); % 左侧像素值与当前像素值之差
        quant = round(diff/10); % 量化
        dec_quant = quant*10; % 反量化
        dec_diff = [blk(:, 1, :) dec_quant] + 0.5; % 反差分
        dec_blk = cumsum(dec_diff, 2); % 恢复图像块
        I_dec(blk_size*(i-1)+1:blk_size*i, blk_size*(j-1)+1:blk_size*j, :) = uint8(dec_blk);
    end
end

% 二阶DPCM编码和解码
for i = 1:h_blk_num
    for j = 1:w_blk_num
        blk = double(I(blk_size*(i-1)+1:blk_size*i, blk_size*(j-1)+1:blk_size*j, :));
        diff1 = blk(:, 2:end, :) - blk(:, 1:end-1, :); % 左侧像素值与当前像素值之差
        diff2 = blk(2:end, :, :) - blk(1:end-1, :, :); % 上方像素值与当前像素值之差
        diff = [diff1(:, 1, :) diff1(:, 2:end, :) diff2(1, :, :) diff2(2:end, :, :)]; % 二阶差分
        quant = round(diff/10); % 量化
        dec_quant = quant*10; % 反量化
        dec_diff1(:, 1, :) = [blk(:, 1, :) dec_quant(:, 1)]; % 反差分
        dec_diff1(:, 2:end, :) = dec_quant(:, 2:end-2) + dec_quant(:, 3:end-1) + dec_diff1(:, 1:end-1, :);
        dec_diff2(1, :, :) = [blk(1, :, :) dec_quant(:, end-1)]; % 反差分
        dec_diff2(2:end, :, :) = dec_quant(:, end) + dec_quant(:, end-1) + dec_diff2(1:end-1, :, :);
        dec_blk = dec_diff1 + dec_diff2 - 0.5; % 恢复图像块
        I_dec(blk_size*(i-1)+1:blk_size*i, blk_size*(j-1)+1:blk_size*j, :) = uint8(dec_blk);
    end
end

% 三阶DPCM编码和解码
for i = 1:h_blk_num
    for j = 1:w_blk_num
        blk = double(I(blk_size*(i-1)+1:blk_size*i, blk_size*(j-1)+1:blk_size*j, :));
        diff1 = blk(:, 2:end, :) - blk(:, 1:end-1, :); % 左侧像素值与当前像素值之差
        diff2 = blk(2:end, :, :) - blk(1:end-1, :, :); % 上方像素值与当前像素值之差
        diff3 = blk(2:end, 2:end, :) - blk(1:end-1, 1:end-1, :); % 左上方像素值与当前像素值之差
        diff = [diff1(:, 1, :) diff1(:, 2:end, :) diff2(1, :, :) diff2(2:end, :, :) diff3(1, :, :) diff3(2:end, :, :)]; % 三阶差分
        quant = round(diff/10); % 量化
        dec_quant = quant*10; % 反量化
        dec_diff1(:, 1, :) = [blk(:, 1, :) dec_quant(:, 1)]; % 反差分
        dec_diff1(:, 2:end, :) = dec_quant(:, 2:end-3) + dec_quant(:, 3:end-2) + dec_quant(:, 4:end-1) + dec_diff1(:, 1:end-1, :);
        dec_diff2(1, :, :) = [blk(1, :, :) dec_quant(:, end-3)]; % 反差分
        dec_diff2(2:end, :, :) = dec_quant(:, end-2) + dec_quant(:, end-1) + dec_quant(:, end) + dec_diff2(1:end-1, :, :);
        dec_diff3(1, :, :) = [blk(:, 1, :) dec_quant(:, end-2)]; % 反差分
        dec_diff3(2:end, :, :) = dec_quant(:, end-1) + dec_quant(:, end) + dec_diff3(1:end-1, :, :);
        dec_blk = dec_diff1 + dec_diff2 + dec_diff3 - 0.5; % 恢复图像块
        I_dec(blk_size*(i-1)+1:blk_size*i, blk_size*(j-1)+1:blk_size*j, :) = uint8(dec_blk);
    end
end

% 四阶DPCM编码和解码
for i = 1:h_blk_num
    for j = 1:w_blk_num
        blk = double(I(blk_size*(i-1)+1:blk_size*i, blk_size*(j-1)+1:blk_size*j, :));
        diff1 = blk(:, 2:end, :) - blk(:, 1:end-1, :); % 左侧像素值与当前像素值之差
        diff2 = blk(2:end, :, :) - blk(1:end-1, :, :); % 上方像素值与当前像素值之差
        diff3 = blk(2:end, 2:end, :) - blk(1:end-1, 1:end-1, :); % 左上方像素值与当前像素值之差
        diff4 = blk(2:end, 1:end-1, :) - blk(1:end-1, 2:end, :); % 右上方像素值与当前像素值之差
        diff = [diff1(:, 1, :) diff1(:, 2:end, :) diff2(1, :, :) diff2(2:end, :, :) diff3(1, :, :) diff3(2:end, :, :) diff4(:, end, :) diff4(:, 1:end-1, :)]; % 四阶差分
        quant = round(diff/10); % 量化
        dec_quant = quant*10; % 反量化
        dec_diff1(:, 1, :) = [blk(:, 1, :) dec_quant(:, 1)]; % 反差分
        dec_diff1(:, 2:end, :) = dec_quant(:, 2:end-4) + dec_quant(:, 3:end-3) + dec_quant(:, 4:end-2) + dec_quant(:, 5:end-1) + dec_diff1(:, 1:end-1, :);
        dec_diff2(1, :, :) = [blk(1, :, :) dec_quant(:, end-4)]; % 反差分
        dec_diff2(2:end, :, :) = dec_quant(:, end-3) + dec_quant(:, end-2) + dec_quant(:, end-1) + dec_quant(:, end) + dec_diff2(1:end-1, :, :);
        dec_diff3(1, :, :) = [blk(:, 1, :) dec_quant(:, end-3)]; % 反差分
        dec_diff3(2:end, :, :) = dec_quant(:, end-2) + dec_quant(:, end-1) + dec_quant(:, end) + dec_diff3(1:end-1, :, :);
        dec_diff4(:, end, :) = [blk(1, end, :) dec_quant(:, end-2)]; % 反差分
        dec_diff4(:, 1:end-1, :) = dec_quant(:, end-1) + dec_quant(:, end) + dec_diff4(:, 2:end, :);
        dec_blk = dec_diff1 + dec_diff2 + dec_diff3 + dec_diff4 - 0.5; % 恢复图像块
        I_dec(blk_size*(i-1)+1:blk_size*i, blk_size*(j-1)+1:blk_size*j, :) = uint8(dec_blk);
    end
end

% 显示原始图像和恢复图像
figure;
subplot(1, 2, 1); imshow(I); title('Original Image');
subplot(1, 2, 2); imshow(I_dec); title('Reconstructed Image');

以上代码实现了一阶、二阶、三阶、四阶DPCM编码和解码恢复图像，并使用MATLAB内置的`imread`和`imshow`函数进行图像读取和显示。需要注意的是，代码中的量化矩阵和编码方式仅作为示例，实际应用中需要根据具体情况进行选择和调试。