I have a iterate undistorttImage function question for version 2016a

I also posted the question here if you prefer : http://stackoverflow.com/questions/38907782/iterate-function-for-matlab-r2016a

[Andrew Nault]

The code shown below is what I used to solve my metadata problem. In it I store image capture date only:

load('C:\mypath\workspace.mat')
p = which('G0011363.JPG');
filelist = dir([fileparts(p) filesep '*.JPG']);
fileNames = {filelist.name};
   
fileNames_size = size(fileNames,2);
number_of_colums = fileNames_size;
   
for k = 1:number_of_colums
    k2 = imfinfo(fileNames{k});
    k3 = k2.FileModDate;
    imwrite(undistortImage(imread(fileNames{k}), cameraParams2cof, 'OutputView', 'valid'), (strcat(int2str(k), '_R2_3COF.jpg')), 'jpg', 'comment', k3);    
end

[Andrew Nault]

This is the code I finally ended up using. Note: DateTime and total seconds elapsed are added to the file name in lieu of standard image metadata.

load('C:\redacted_lol\workspace.mat')
p = which('G0017317.JPG');
filelist = dir([fileparts(p) filesep '*.JPG']);
fileNames = {filelist.name};
fileNames_size = size(fileNames,2);
number_of_colums = fileNames_size;
k5 = 0;
for k = 1:number_of_colums
    k2 = imfinfo(fileNames{k});
    k3 = k2.DateTime;
    k4 = strrep(k3(12:19), ':', '-');
    k5 = k5 + 2;
    imwrite(undistortImage(imread(fileNames{k}), cameraParams2cof, 'OutputView', 'valid'), (strcat(int2str(k5), 'SECONDS_LEFTT_', k4, '.png')), 'png', 'comment', k3);    
end

Answer 1

[Image Analyst]

Then don't pass in the image, pass in the index and the cell array

function output = undistortImage(filenames, i)
try
    output = []; % Initialize
    filename = filenames{i};
    originalImage = imread(filename);
    % More code....

DO NOT have the output variable change it's name with the loop index - bad bad idea. See http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

Put the output image into a cell array if you really, really need to keep it after your loop exits.

allImages{k} = undistortImage(filenames, k); % Save image into a cell array and use up a huge amount of memory.

Normally one would just call it thisImage and consume it during the same iteration and overwrite it on every iteration

thisImage = undistortImage(filenames, k); % thisImage will get replaced every iteration and is more memory efficient.

By the way, don't use i and j as loop iterators because they stand for the imaginary variable. That's why I suggest using k instead.