Code explanation (bw)

Any one know what is the meaning of this coding?

imageOutR(bw2(:)~=0) = Ro(bw2(:)~=0);
imageOutG(bw2(:)~=0) = Go(bw2(:)~=0);
imageOutB(bw2(:)~=0) = Bo(bw2(:)~=0);
Dccc = cat(3,imageOutR,imageOutG,imageOutB);

how to explain this code?

imageOutR(bw2(:)~=0) = Ro(bw2(:)~=0);

Answer 1

[Image Analyst]

It's someone (not a super skilled MATLAB programmer evidently) trying to take part of R, G, and B images that are defined by a mask (logical, binary image), bw2, and put them into different R, G, and B images, which they then concatenate into an RGB image called Dcc. It could be written simpler as:

imageOutR(bw2) = Ro(bw2); % Paste Red image inside bw2 onto imageOutR
imageOutG(bw2) = Go(bw2); % Paste Green image inside bw2 onto imageOutG
imageOutB(bw2) = Bo(bw2); % Paste Blue image inside bw2 onto imageOutB
% Concatenate individual color channels into a 3-D true color RGB image.
Dccc = cat(3,imageOutR,imageOutG,imageOutB);

Answer 2

[Awais Saeed]

The (:) reshapes a matrix into a column vector.

imageOutR = [zeros(1,3); 2 5 13; 0 1 2; 1 3 5] % 4x4 matrix for instance

imageOutR = 4×3

0 0 0 2 5 13 0 1 2 1 3 5

bw2 = randi([0 1],1,10)

bw2 = 1×10

1 1 1 1 0 1 0 1 1 0

% get indices of bw2 where non-zero elements resides
% get elements of imageOutR at those indices
imageOutR(bw2(:)~=0)

ans = 7×1

0 2 0 1 5 3 0

Ro = magic(4)

Ro = 4×4

16 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1

% replace elements of imageOutR with corresponding Ro's elements at those indices
imageOutR(bw2(:)~=0) = Ro(bw2(:)~=0)

imageOutR = 4×3

16 0 3 5 11 13 9 1 2 4 14 5

cat() is for concatenation of arrays

Answer 3

[yanqi liu]

sir，may be check it by some demo

clc; clear all; close all;
RGB = imread('football.jpg');
% 3 channel
Ro=RGB(:,:,1);Go=RGB(:,:,2);Bo=RGB(:,:,3);
% make mask
bw2 = im2bw(RGB);
% get mask data in image
imageOutR = zeros(size(Ro));imageOutG = zeros(size(Ro));imageOutB = zeros(size(Ro));
imageOutR(bw2(:)~=0) = Ro(bw2(:)~=0);
imageOutG(bw2(:)~=0) = Go(bw2(:)~=0);
imageOutB(bw2(:)~=0) = Bo(bw2(:)~=0);
Dccc = uint8(cat(3,imageOutR,imageOutG,imageOutB));
figure;
montage({RGB,bw2,Dccc}, 'Size', [1 3], 'BackgroundColor', 'r', 'BorderSize', [3 3])

[Image Analyst]

Nice illustration/demo. Like I said in my answer, you do not need bw2(:)~=0. You can simply replace it by bw2

[yanqi liu]

yes，sir，use logical matrix can use directly