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compphys/exo4/imgcomp.m
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imgcomp.m
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classdef imgcomp
properties
sing
U
V
chnb
image % constant
end
methods
% img = input image
% chnb = number of channels (red, green, blue, alpha, bw, ecc...)
function obj = imgcomp(img, chnb)
obj.sing = cell(chnb,1);
obj.U = cell(chnb,1);
obj.V = cell(chnb,1);
obj.chnb = chnb;
for k = 1:chnb
[u, D, v] = svd(double(img(:,:,k)));
obj.sing{k} = diag(D);
obj.U{k} = u;
obj.V{k} = v;
end
obj.image = img;
end
function out = m(obj)
[out,~] = size(obj.U{1});
end
function out = n(obj)
[out,~] = size(obj.V{1});
end
function v = econ_V(obj, N)
v = cell(obj.chnb,1);
for k = 1:obj.chnb
v{k} = obj.V{k}(1:obj.n(), N);
end
end
function u = econ_U(obj, N)
u = cell(obj.chnb,1);
for k = 1:obj.chnb
u{k} = obj.U{k}(1:obj.m(), N);
end
end
function s = econ_singular(obj, N)
s = cell(obj.chnb,1);
for k = 1:obj.chnb
s{k} = obj.sing{k}(1:N);
end
end
function compimg = compress(obj,N)
compimg = zeros(obj.m(), obj.n(), obj.chnb);
for k = 1:obj.chnb
sigma = zeros(obj.m(),obj.n());
sigma(1:N,1:N) = diag(obj.sing{k}(1:N));
compimg(:,:,k) = obj.U{k} * sigma * obj.V{k}';
end
compimg = uint8(compimg);
end
end
end
%function [compimg, singval, U, V] = compress(img, N)
% %cell struct: sing{color_channel, object}
% %color channel is in {red, green, blue}
% %object is in {sing, U, V}
%sing = cell(3,3);
%for k = 1:3
% [U, D, V] = svd(double(img(:,:,k)));
% sing{k,1} = diag(D);
% sing{k,2} = U;
% sing{k,3} = V;
%end
%
%M = length(sing{1,2});
%oldN = length(sing{1,3});
%compimg = zeros(M, oldN, 3);
%
%singval = zeros(N, 3);
%U = zeros(M, N, 3);
%V = zeros(N, N, 3);
%
%for k = 1:3
% sigma = zeros(M,oldN);
% sigma(1:N,1:N) = diag(sing{k,1}(1:N));
% singval(:,k) = sing{k,1}(1:N);
% U(:,:,k) = sing{k,2}(:, 1:N);
% V(:,:,k) = sing{k,3}(:, 1:N);
% %compimg(:,:,k) = sing{k,2} * sigma * sing{k,3}';
% comping(:,:,k) = (U(:,:,k) * sigma(1:N,:)) * V(:,:,k)';
%end
%
%compimg = uint8(compimg);
%end
%
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