% c=[-9,0,-11,-1,-1,0,-1,0,0,0,0,-1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];
% invcode=izigzagScan(c,8,8);
%% input: A : zig-zag matrix
%% needNumCoefficient : how many coefficient you want to maintain 8*8矩阵按inv zig-zag排列
%% output: dctVector: vector contain coefficients by col
function mtr = invzigzag(vec, m, n)
% izigzagScan(vec, m, n) Inverse zigzag scan.
% mtr = izigzagScan(vec, m, n) inverse zigzag scan of vec, and the target
% matrix is m-by-n. The input parameter vec is an 1-by-k vector. If the
% length of vector is smaller than the size of mtr (i.e. k < m*n), then, the
% pargram will use 0 to fill the matrix. If k > m*n, the vector will be truncated.
%
% version: v1.0
% author: tianlan
% time: Dec 16, 2016
% CHECK INPUT ARGUMENTS
if nargin < 3
error('Not enough input arguments!');
elseif nargin > 3
error('Too many input arguments!');
end
% Get length of vector.
[mv,nv,tv] = size(vec);
if tv ~= 1 || mv ~=1
error('The input vector needs to be 1-by-k vector!');
end
if nv < m*n % if nv < m*n, then, use 0 to fill the matrix.
vec = [vec, zeros(1,m*n-nv)];
end
% REVERSE SCAN A VECTOR BY USING ZIGZAG ORDER.
mtr = zeros(m,n);
% zigzag scan.
x = 1;
y = 1;
vecNum = 0;
vecNum = vecNum + 1;
mtr(x,y) = vec(1,vecNum);
while 1
% arrive right-up border, needs to change direction.
if (y+1) <= n && x == 1 % towards right one step.
y = y + 1;
elseif (y+1) > n && (x+1) <= m % towards down one step.
x = x + 1;
else
break;
end
vecNum = vecNum + 1;
mtr(x,y) = vec(1,vecNum) ;
% judge the scan process is arrived the right-down corner (i.e. mtr(m,n)) or not.
if x == m && y == n
break;
end
% scan the matrix towards with left-down direction.
while (y-1) >= 1 && (x+1) <= m
y = y - 1;
x = x + 1;
vecNum = vecNum + 1;
mtr(x,y) = vec(1,vecNum);
end
% arrive the left-down border, needs to change direction.
if (x+1) <= m && y == 1% towards down one step.
x = x + 1;
elseif (y+1) <= n && x == m % towards right one step.
y = y + 1;
else
break;
end
vecNum = vecNum + 1;
mtr(x,y) = vec(1,vecNum);
% judge the scan process is arrived the right-down corner (i.e. mtr(m,n)) or not.
if x == m && y == n
break;
end
% scan the matrix towards with right-up direction.
while (x-1) >= 1 && (y+1) <= n
x = x - 1;
y = y + 1;
vecNum = vecNum + 1;
mtr(x,y) = vec(1,vecNum);
end
end
end
