If what you're trying to do is get the standard deviation of the regions specified by the label matrix, try this.
clear variables; clc; close all
IMG = imread('sources/blacklight2.jpg'); % i used my own test image
blue = IMG(:,:,3);
th = graythresh(blue);
bw = imbinarize(blue,th);
bw = imclearborder(bw,8);
seD = strel('disk',3);
bw = imopen(bw,seD);
CC = bwconncomp(bw, 8);
L = labelmatrix(CC);
xx = [];
a = 1;
LL1 = L;
for i = 1:CC.NumObjects
% only evaluate groups above a certain size
if length(CC.PixelIdxList{i})<1000
% idk what you're doing with LL1
% i'll assume this is for something else
% LL was being rewritten and unused, so I removed it
LL1(LL1==i) = 0;
else
roidata=double(blue(L==i)); % extract the ROI
xx(a,:) = [i std(roidata(:))]; % write to output array
a = a+1;
end
end
xx
If LL1 isn't used for anything outside this scope, then it simplifies to
clear variables; clc; close all
IMG = imread('sources/blacklight2.jpg');
blue = IMG(:,:,3);
th = graythresh(blue);
bw = imbinarize(blue,th);
bw = imclearborder(bw,8);
seD = strel('disk',3);
bw = imopen(bw,seD);
CC = bwconncomp(bw, 8);
L = labelmatrix(CC);
xx = [];
a = 1;
for i = 1:CC.NumObjects
if length(CC.PixelIdxList{i})>=1000
roidata=double(blue(L==i));
xx(a,:) = [i std(roidata(:))];
a = a+1;
end
end
xx
idk if that helps
