Matlab Can'；t使用JPEG算法保存压缩图像

我想问一下jpeg压缩的问题。 我无法保存压缩后的图像，只能保存解压缩后的图像。 我也不会做熵解码。 我希望有人能帮助我。我使用的是MatlabR2012A。我需要的压缩图像文件，以表明我已经压缩，可以计算之间的比例未压缩和压缩的图像。代码如下：

function [ output_image, compressed_vector, ratio ] = jpeg_computing( input_image, q)
runtime = cputime;
n = 8; % size of blocks
dim1 = size(input_image,1); % image width
dim2 = size(input_image,2); % image height
dim3 = size(input_image,3); % number of channels
if (dim3 > 1)
    ycbcrmap = rgb2ycbcr(im2double(input_image)); % mapping, need double for DCT
else
    ycbcrmap = im2double(input_image);
end
% here you can (should) also paste downsampling of chroma components
output_image = zeros(size(input_image), 'double');
compressed_vector = 0;
[qY, qC] = get_quantization(q); % get quantization matrices
T = dctmtx(n); % DCT matrix
scale = 255; % need because DCT values of YCbCr are too small to be quantized
% Block processing functions
dct = @(block_struct) T * block_struct.data * T';
invdct = @(block_struct) T' * block_struct.data * T;
quantY = @(block_struct) round( block_struct.data./qY);
dequantY = @(block_struct) block_struct.data.*qY;
quantC = @(block_struct) round( block_struct.data./qC);
dequantC = @(block_struct) block_struct.data.*qC;
entropy_proc = @(block_struct) entropy_cod(block_struct.data, n);
%---------------------------
for ch=1:dim3
    % encoding ---------------------------
    channel = ycbcrmap(:,:,ch); % get channel
    % compute scaled forward DCT
    channel_dct = blockproc(channel, [n n], dct).*scale; 
    % quantization
    if (ch == 1)
        channel_q = blockproc(channel_dct,[n n], quantY);  % quantization for luma
    else
        channel_q = blockproc(channel_dct,[n n], quantC);  % quantization for colors
    end
    entropy_out = blockproc(channel_q,[n n], entropy_proc); % compute entropy code
    entropy_code = get_entropy(entropy_out, n, dim1, dim2); % get entropy code without
    zeros on the end

    [comp, dict] = huffman_cod(entropy_code); % huffman encoding
    compressed_vector = cat(1, compressed_vector, comp); % add to output
    % decoding ---------------------------
    dsig = reshape(huffmandeco(comp, dict), size(entropy_code)); % huffman decoding 
    if (isequal(entropy_code,dsig) ~= 1) % check if decoding is correct
        input('error in huffmandeco')
    end
    % put entropy decoding here
    % dequantization
    if (ch == 1)
        channel_q = blockproc(channel_q,[n n], dequantY);
    else
        channel_q = blockproc(channel_q,[n n], dequantC);
    end
    output_data = blockproc(channel_q./scale,[n n],invdct); % inverse DCT, scale back
    output_image(:,:,ch) = output_data(1:dim1, 1:dim2); % set output
end
%---------------------------
compressed_vector = compressed_vector(2:length(compressed_vector)); % remove first
symbol
if (dim3 > 1)
    output_image = im2uint8(ycbcr2rgb(output_image)); % back to rgb uint8
else
    output_image = im2uint8(output_image); % back to rgb uint8
end
runtime = cputime-runtime;
% compute compression ratio
% compressed_vector is binary, input image has one byte per pixel
ratio = (dim1 * dim2 * dim3 / (length(compressed_vector) /8));
tampil = guidata(gcbo);
str1 = num2str(ratio,'%1.2f %%');
str2 = num2str(runtime,'%1.2f s');
set(tampil.edit2,'String',str1);
set(tampil.edit3,'String',str2);
axes(tampil.axes_asli), imshow(input_image) % show results
axes(tampil.axes_hasil), imshow(output_image) % show results
end


function [entropy_code] = get_entropy (entropy_raw_matrix, n, dim1, dim2)
% go by tiles in loops to extract shortened entropy codes (without
% zeros on the end)
step = n-1; % poor stuff for entropy coding iterations, should be avoided
tile = entropy_raw_matrix(1:1+step, 1:1+step);
entropy_code = tile(1:find(tile(:),1,'last'));
for i=step+2:step+1:dim1-step
    for j=step+2:step+1:dim2-step
        tile = entropy_raw_matrix(i:i+step, j:j+step);
        entropy_code = cat(2, entropy_code, tile(1:find(tile(:),1,'last')));
    end
end
end

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似乎您在编码部分投入了很多精力，但在这里解释的不多。您的问题非常、非常、非常、非常广泛。无法保存压缩图像是什么意思？还有，你不能做熵编码是什么意思？你有哪些具体问题？另外，请编辑您的代码，将其缩小到您遇到问题的确切位置。写那么多代码并不能解决你的问题。谢谢你的帮助。我无法保存压缩文件，因为我知道我们可以在解压算法开始之前保存压缩文件，如*.mat或其他文件格式。在这一部分中，如果（isequal（entropy_code，dsig）~=1）输入（'error in huffmandeco'）结束%，将熵解码放在这里%，如果（ch==1）信道（channel_q=blockproc（channel_q，[n n]，dequantity），则无法进行熵解码；else channel_q=blockproc（channel_q[n]，dequantC）；