ac_code.m

用离散余弦变换实现JPEG编码

%AC系数的HUFFMAN编码
function b = AC_code(x)

%    run - category - length - bsae code length -  base code
table=[...
        0       1       3               2           0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 0  2   4  2 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 0  3   6  3 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
 0  4   8  4 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0
 0  5  10  5 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 
 0  6  12  6 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 
 0  7  14  7 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 
 0  8  18 10 1 1 1 1 1 1 0 1 1 0 0 0 0 0 0 0
 0  9  25 16 1 1 1 1 1 1 1 1 1 0 0 0 0 0 1 0
 0 10  26 16 1 1 1 1 1 1 1 1 1 0 0 0 0 0 1 1
 1  1   5  4 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
 1  2   8  6 1 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 
 1  3  10  7 1 1 1 1 0 0 1 0 0 0 0 0 0 0 0 0
 1  4  13  9 1 1 1 1 1 0 1 1 0 0 0 0 0 0 0 0
 1  5  16 11 1 1 1 1 1 1 1 0 1 1 0 0 0 0 0 0
 1  6  22 16 1 1 1 1 1 1 1 1 1 0 0 0 0 1 0 0
 1  7  23 16 1 1 1 1 1 1 1 1 1 0 0 0 0 1 0 1
 1  8  24 16 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1 0
 1  9  25 16 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1
 1 10  26 16 1 1 1 1 1 1 1 1 1 0 0 0 1 0 0 0
 2  1   6  5 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 
 2  2  10  8 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0
 2  3  13 10 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 
 2  4  20 16 1 1 1 1 1 1 1 1 1 0 0 0 1 0 0 1
 2  5  21 16 1 1 1 1 1 1 1 1 1 0 0 0 1 0 1 0
 2  6  22 16 1 1 1 1 1 1 1 1 1 0 0 0 1 0 1 1
 2  7  23 16 1 1 1 1 1 1 1 1 1 0 0 0 1 1 0 0
 2  8  24 16 1 1 1 1 1 1 1 1 1 0 0 0 1 1 0 1
 2  9  25 16 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 0
 2 10  26 16 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1
 3  1   7  6 1 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0
 3  2  11  9 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0
 3  3  14 11 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 
 3  4  20 16 1 1 1 1 1 1 1 1 1 0 0 1 0 0 0 0
 3  5  21 16 1 1 1 1 1 1 1 1 1 0 0 1 0 0 0 1
 3  6  22 16 1 1 1 1 1 1 1 1 1 0 0 1 0 0 1 0
 3  7  23 16 1 1 1 1 1 1 1 1 1 0 0 1 0 0 1 1
 3  8  24 16 1 1 1 1 1 1 1 1 1 0 0 1 0 1 0 0
 3  9  25 16 1 1 1 1 1 1 1 1 1 0 0 1 0 1 0 1
 3 10  26 16 1 1 1 1 1 1 1 1 1 0 0 1 0 1 1 0
 4  1   7  6 1 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0
 4  2  12 10 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 
 4  3  19 16 1 1 1 1 1 1 1 1 1 0 0 1 0 1 1 1
 4  4  20 16 1 1 1 1 1 1 1 1 1 0 0 1 1 0 0 0
 4  5  21 16 1 1 1 1 1 1 1 1 1 0 0 1 1 0 0 1
 4  6  22 16 1 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0
 4  7  23 16 1 1 1 1 1 1 1 1 1 0 0 1 1 0 1 1
 4  8  24 16 1 1 1 1 1 1 1 1 1 0 0 1 1 1 0 0
 4  9  25 16 1 1 1 1 1 1 1 1 1 0 0 1 1 1 0 1
 4 10  26 16 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 0
 5  1   8  7 1 1 1 1 0 1 0 0 0 0 0 0 0 0 0 0
 5  2  12 10 1 1 1 1 1 1 1 0 0 1 0 0 0 0 0 0 
 5  3  19 16 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 1
 5  4  20 16 1 1 1 1 1 1 1 1 1 0 1 0 0 0 0 0
 5  5  21 16 1 1 1 1 1 1 1 1 1 0 1 0 0 0 0 1
 5  6  22 16 1 1 1 1 1 1 1 1 1 0 1 0 0 0 1 0
 5  7  23 16 1 1 1 1 1 1 1 1 1 0 1 0 0 0 1 1
 5  8  24 16 1 1 1 1 1 1 1 1 1 0 1 0 0 1 0 0
 5  9  25 16 1 1 1 1 1 1 1 1 1 0 1 0 0 1 0 1
 5 10  26 16 1 1 1 1 1 1 1 1 1 0 1 0 0 1 1 0
 6  1   8  7 1 1 1 1 0 1 1 0 0 0 0 0 0 0 0 0
 6  2  13 11 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 
 6  3  19 16 1 1 1 1 1 1 1 1 1 0 1 0 0 1 1 1
 6  4  20 16 1 1 1 1 1 1 1 1 1 0 1 0 1 0 0 0
 6  5  21 16 1 1 1 1 1 1 1 1 1 0 1 0 1 0 0 1
 6  6  22 16 1 1 1 1 1 1 1 1 1 0 1 0 1 0 1 0
 6  7  23 16 1 1 1 1 1 1 1 1 1 0 1 0 1 0 1 1
 6  8  24 16 1 1 1 1 1 1 1 1 1 0 1 0 1 1 0 0
 6  9  25 16 1 1 1 1 1 1 1 1 1 0 1 0 1 1 0 1
 6 10  26 16 1 1 1 1 1 1 1 1 1 0 1 0 1 1 1 0
 7  1   9  8 1 1 1 1 1 0 0 1 0 0 0 0 0 0 0 0
 7  2  13 11 1 1 1 1 1 1 1 1 0 0 1 0 0 0 0 0 
 7  3  19 16 1 1 1 1 1 1 1 1 1 0 1 0 1 1 1 1
 7  4  20 16 1 1 1 1 1 1 1 1 1 0 1 1 0 0 0 0
 7  5  21 16 1 1 1 1 1 1 1 1 1 0 1 1 0 0 0 1
 7  6  22 16 1 1 1 1 1 1 1 1 1 0 1 1 0 0 1 0
 7  7  23 16 1 1 1 1 1 1 1 1 1 0 1 1 0 0 1 1
 7  8  24 16 1 1 1 1 1 1 1 1 1 0 1 1 0 1 0 0
 7  9  25 16 1 1 1 1 1 1 1 1 1 0 1 1 0 1 0 1
 7 10  26 16 1 1 1 1 1 1 1 1 1 0 1 1 0 1 1 0
 8  1   9  8 1 1 1 1 1 0 1 0 0 0 0 0 0 0 0 0
 8  2  17 15 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0
 8  3  19 16 1 1 1 1 1 1 1 1 1 0 1 1 0 1 1 1
 8  4  20 16 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0
 8  5  21 16 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 1
 8  6  22 16 1 1 1 1 1 1 1 1 1 0 1 1 1 0 1 0
 8  7  23 16 1 1 1 1 1 1 1 1 1 0 1 1 1 0 1 1
 8  8  24 16 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0
 8  9  25 16 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1
 8 10  26 16 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 0
 9  1  10  9 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 
 9  2  18 16 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1
 9  3  19 16 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0
 9  4  20 16 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 1
 9  5  21 16 1 1 1 1 1 1 1 1 1 1 0 0 0 0 1 0
 9  6  22 16 1 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1
 9  7  23 16 1 1 1 1 1 1 1 1 1 1 0 0 0 1 0 0
 9  8  24 16 1 1 1 1 1 1 1 1 1 1 0 0 0 1 0 1
 9  9  25 16 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 0
 9 10  26 16 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1
10  1  10  9 1 1 1 1 1 1 0 0 1 0 0 0 0 0 0 0 
10  2  18 16 1 1 1 1 1 1 1 1 1 1 0 0 1 0 0 0
10  3  19 16 1 1 1 1 1 1 1 1 1 1 0 0 1 0 0 1
10  4  20 16 1 1 1 1 1 1 1 1 1 1 0 0 1 0 1 0
10  5  21 16 1 1 1 1 1 1 1 1 1 1 0 0 1 0 1 1
10  6  22 16 1 1 1 1 1 1 1 1 1 1 0 0 1 1 0 0
10  7  23 16 1 1 1 1 1 1 1 1 1 1 0 0 1 1 0 1
10  8  24 16 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1 0
10  9  25 16 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1
10 10  26 16 1 1 1 1 1 1 1 1 1 1 0 1 0 0 0 0
11  1  10  9 1 1 1 1 1 1 0 1 0 0 0 0 0 0 0 0 
11  2  18 16 1 1 1 1 1 1 1 1 1 1 0 1 0 0 0 1
11  3  19 16 1 1 1 1 1 1 1 1 1 1 0 1 0 0 1 0
11  4  20 16 1 1 1 1 1 1 1 1 1 1 0 1 0 0 1 1
11  5  21 16 1 1 1 1 1 1 1 1 1 1 0 1 0 1 0 0
11  6  22 16 1 1 1 1 1 1 1 1 1 1 0 1 0 1 0 1
11  7  23 16 1 1 1 1 1 1 1 1 1 1 0 1 0 1 1 0
11  8  24 16 1 1 1 1 1 1 1 1 1 1 0 1 0 1 1 1
11  9  25 16 1 1 1 1 1 1 1 1 1 1 0 1 1 0 0 0
11 10  26 16 1 1 1 1 1 1 1 1 1 1 0 1 1 0 0 1
12  1  11 10 1 1 1 1 1 1 1 0 1 0 0 0 0 0 0 0 
12  2  18 16 1 1 1 1 1 1 1 1 1 1 0 1 1 0 1 0
12  3  19 16 1 1 1 1 1 1 1 1 1 1 0 1 1 0 1 1
12  4  20 16 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0
12  5  21 16 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 1
12  6  22 16 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0
12  7  23 16 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1
12  8  24 16 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0
12  9  25 16 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 1
12 10  26 16 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 0
13  1  12 11 1 1 1 1 1 1 1 1 0 1 0 0 0 0 0 0 
13  2  18 16 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1
13  3  19 16 1 1 1 1 1 1 1 1 1 1 1 0 0 1 0 0
13  4  20 16 1 1 1 1 1 1 1 1 1 1 1 0 0 1 0 1
13  5  21 16 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1 0
13  6  22 16 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1
13  7  23 16 1 1 1 1 1 1 1 1 1 1 1 0 1 0 0 0
13  8  24 16 1 1 1 1 1 1 1 1 1 1 1 0 1 0 0 1
13  9  25 16 1 1 1 1 1 1 1 1 1 1 1 0 1 0 1 0
13 10  26 16 1 1 1 1 1 1 1 1 1 1 1 0 1 0 1 1
14  1  13 12 1 1 1 1 1 1 1 1 0 1 1 0 0 0 0 0
14  2  18 16 1 1 1 1 1 1 1 1 1 1 1 0 1 1 0 0
14  3  19 16 1 1 1 1 1 1 1 1 1 1 1 0 1 1 0 1
14  4  20 16 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0
14  5  21 16 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1
14  6  22 16 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0
14  7  23 16 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1
14  8  24 16 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1 0
14  9  25 16 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1
14 10  26 16 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 0
15  1  17 16 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 1
15  2  18 16 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 0
15  3  19 16 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1
15  4  20 16 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0
15  5  21 16 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1
15  6  22 16 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0
15  7  23 16 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1
15  8  24 16 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0
15  9  25 16 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1
15 10  26 16 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0
 0  0   4  4 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0
15  0  12 12 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0];
%所有的非零输入
ix = find(x~=0); 
%非零输入的长度
Nx = length(ix);  
%编码输出
b=[];
%对每一个非零元素循环编码
for n = 1:1:Nx,
   prefix = [];
   % 检查之前的零的长度
    if (n == 1)
        run = ix(1) - 1; %n==1时，没有ix(n-1)项，故直接－1
    else
        run = ix(n) - ix(n-1) - 1;
    end
   % 当零的长度超过15时，分段编码
   while run > 15, 
      b = [ b 1 1 1 1 1 1 1 1 0 1 1 1 ];
      run = run-15;
   end
   % 检查是否该块结束
   if x(ix(n)) == 999, 
       b = [ b 1 0 1 0 ]; 
   else
      tmp = x_int2bin(x(ix(n)));          %转换成二进制
      category = length(tmp);             %确定输入范围
      row = run*10 + category;            %对于任意的先行0的数量，有10种范围，以次确定查表行位置
      prefix = table( row,5:table(row,4)+4 );  %查表获取编码
      if x(ix(n))<0,       
         tmp = ones(1,category)-tmp;           %输入为负数则取补码
      end
      % 前缀码＋尾码
      b=[ b prefix tmp(1:category) ];
   end
end