Concatenate series of images from different folders

I was trying to achieve following functionalities:

extract pic1 from folder2 and put it to the left part of the newImg, extract pic2 from folder2 and put it to the right part of the newImg, Then combine the left part and right part together to be a new image.

My question is I want to implement this function for a series of images, which means a series of images from folder1 and a series of images from folder2, then extract all the images from folder1, put it to the left part of the newImg; same for folder 2, extract all the images from folder2 and put it the right part of the newImg.

I have implemented to read series of images from different folders, but when trying to concatenate the images, matlab throws an error saying unexpected expression.

Please check my code below: ==========================================================================

clc;
clear all;
close all;

%%Read images from folder1

oriDir = '/home/folder1/';
oriList = dir(fullfile(oriDir,'*.jpg'));

%read images from folder2

convDir = '/home/folder2/';
convList = dir(fullfile(convDir,'*.bmp'));

for i = 1:length(oriList)
    oriPath = [oriDir oriList(1).name];
    oriImg = imread(oriPath);
end 

for j = 1:length(convList)
    convPath = [convDir convList(1).name];
    convImg = imread(convPath);
end

 newImg = cat(2,oriImg,convImg);

 newImg = uint8(newImg);
 imshow(newImage);

[Adam]

Have you debugged to check the rest of it works as expected?

e.g. you put 'foler2' instead of 'folder2' so your error may simply be because you have an empty list of files so no convolution happens.

[awa]

The original cold is correct. The ones I pasted here is typo because I changed the original folder same into a simpler one.

I corrected the typo now here.

Answer 1

[Azzi Abdelmalek]

You should replace

oriPath = [oriDir oriList(1).name]
convPath = [convDir convList(1).name];

by

oriPath=fullfile(oriDir,oriList(1).name)
convPath =fullfile(convDir,convList(1).name)

Answer 2

[Walter Roberson]

%%Read images from folder1

oriDir = '/home/folder1/';
oriList = dir(fullfile(oriDir, '*.jpg'));
num_ori = length(oriList);

%read images from folder2

convDir = '/home/folder2/';
convList = dir(fullfile(convDir, '*.bmp'));
num_conv = length(convList);

numfile = min(num_ori, num_conv);

oriImg = cell(numfile, 1);

for i = 1 : numfile
    ori_name = oriList(i).name;
    oriPath = fullfile(oriDir, ori_name);
    ori_img = imread(oriPath);
    oriImg{i} = ori_img;
    conv_name = convList(i).name;
    convPath = fullfile(convDir, conv_name);
    conv_img = imread(convPath);
    convImg{i} = conv_img;
    if size(ori_img}, 1) == size(conv_img, 1) && size(ori_img, 3) == size(conv_img, 3)
      newImg{i} = cat(2, ori_img, conv_img);
      imshow(newImg{i});
      title( sprintf('"%s" with "%s"', ori_name, conv_name) );
      pause(1);
    else
     fprintf('ori "%s" is incompatible size [%d,%d,%d] with conv "%s" [%d,%d,%d]', ...
             ori_name, size(ori_img,1), size(ori_img,2), size(ori_img,3), ...
             conv_name, size(conv_img,1), size(conv_img,2), size(conv_img,3) );
     newImg{i} = [];
     imshow(0);
     title( sprintf('"%s" incompatible with "%s"', ori_name, conv_name) );
   end
end

[awa]

Hi Walter,

Thanks a lot for your detailed answer.

I have one doubt, what does the two lines code mean here ? Why should I obtain the minimum value of the image arrays ?

numfile = min(num_ori, num_conv);
oriImg = cell(numfile, 1);

[Walter Roberson]

If there are not the same number of ori files as there are conv files, then if you assume they are the same you are going to try to match a non-existant file against an existing file. The number of pairs that you can be sure you can match is the minimum of the number of files on each side. For example, if the search finds 7 ori files and only 5 conv files then there can be only min(7,5) = 5 outputs.

[awa]

I tried you code, but I always encountered an error saying that "Error: Unexpected MATLAB expression.".

I debugged the code, found the error appears when executing the code at

oriDir = '/home/folder1/';
oriList = dir(fullfile(oriDir, '*.jpg'));

I don't why this would occur. I don't there are any expression contained in the beginning.

Could you please help?

Thank you.

[Azzi Abdelmalek]

Repmove one bracket, instead of

oriList = dir(fullfile(oriDir, '*.jpg'));

it should be

oriList = dir(fullfile(oriDir, '*.jpg');