How to convert jpg image files to mat files

Hello, I have been give a task to convert multiple jpg image files to matlab mat files each having 5 fields. I tried using the import data tab but was only given one field. But when the matlab function 'load(filename,'-mat')' was used it produced a mat file with 5 field names. Please could anyone help me with a code to convert multiple jpg images to give same result. I have attached 3 of the jpg images in question. Thanks.

[Image Analyst]

First you read the image(s) into MATLAB with imread(). Now, how many image arrays go into each .mat file? One? If so, then one field would be the image array itself, but what do you want the other 4 fields to be?

Answer 1

[Star Strider]

No conversion necessary. Just save them in the .mat file as images.

For example:

img_str = {sprintf('IR_%04d.jpg\n', 6710:6715)};            % Generate Image Filenames To Save
img_names = regexp(img_str{:}(1:end-1), '\n', 'split');     % Cell Array Of Them
filename = 'IR_Files01.mat';                                % Filename For ‘.mat’ File
save(filename, img_names)                                   % Save To File

I tested only the first two lines (for ‘img_str’ and ‘img_names’), so I leave the rest for you to experiment with. You may have to create one or two loops to automate the filename and image name start number creation.

[Ogheneochuko]

Thanks so much. The jpg images converted to mat files are used to plot labelled (temperature) contours. And it has been observed that when the conversion produces a single field, the labelled temperatures are inaccurate whereas when 5 fields are produced, as is the case when using the 'load(filename,'-mat')' command, the temperatures are correct. Please is there a way of incorporating the 'load(filename,'-mat')' command in an iteration loop? If so could you please help me with a code to proceed with. Thanks again.

[Image Analyst]

I don't understand what you're trying to say. It doesn't matter if an image array is stored as a JPG (a big no-no for image analysis) or a PNG file or a .Mat file because once it's recalled into MATLAB you have an image array. So what do you mean that five fields are produces, or one field? When you do this

storedStructure = load(yourMatFileName);

You'll get a structure with an many fields attached to it as variables that you saved. So if you did

save(yourMatFileName, 'myImage');

Then stored structure will have one field called myImage. If you did

save(yourMatFileName, 'myImage', 'myVar1', 'myVar2');

then storedStructure will have 3 fields, one that contains each variable you saved. You can get then back to individual variables from the structure if you do this

myImage = storedStructure.myImage;
myVar1 = storedStructure.myVar1;
myVar2 = storedStructure.myVar2;

So, like I asked way up top in my comment, what are your 5 fields? What 5 variables did you store with save() and then later recall with load()?

[Ogheneochuko]

Thanks again. I have attached some pictures to better explain what I am trying to describe. Pic 1 illustrates the mat file produced when a thermal imaging computer software is used to convert a jpg thermal image to mat file. But pic 2 depicts the mat file produced when the same jpg image is converted to mat file using the program I used below;

inputPath = 'F:\Matlab Project'; 
% uigetdir('C:\')
dir([inputPath '\*.jpg'])
listFiles = dir([inputPath '\*.jpg']);
for i = 1:length(listFiles)
I = imread([inputPath '\' listFiles(i).name]);
[fpath radical ext] = fileparts([inputPath ' \' listFiles(i).name] ); 
     A = (24/10).*I;
     A = mean(I,3);
     A = (100/455).*A;
     contour(flipud(A));
     [C,h] = contour(interp2(flipud(A),'spline'));    
     clabel(C,h);
     pause;
 end

The reason for the concern is that when the contour is produced with the mat file from pic1, it gives the image in pic3 which is different from the contour in pic4 generated from the mat file in pic2, in terms of the temperature gradient.

Please assist and thank you.

[Ogheneochuko]

Upon checking today, I found that the earlier attachment in excel containing the pictures illustrating the issue at hand, had lost all information. Hence I deleted it and replaced it with pictures in jpeg format. Thanks.

[Ogheneochuko]

Also the mat file in pic2 being in unit8 has lost some information and this is seen in the temperature gradient values on the contours.

[Hien Nguyen]

I tried your code, but by somehow, it didn't work. the error message is "incorrect use of save, it must include a string"

[Walter Roberson]

Several different code versions were posted; please post the version you are testing.

[Image Analyst]

Correction:

save(filename, 'img_names');

[Akhil Sreenivasulu]

To store images into mat file

%contains all images from 10.jpg to 30.jpg without spacing
    img_str = {sprintf('%02d.jpg\n', 10:30)}; 
% Splits the one value into multiple matrix array, main variable
    img_names = regexp(img_str{:}(1:end-1), '\n', 'split'); 
% if you don't give ' in save command it give error.
    save('my_file_name.mat','img_names');

To load the mat file into command window

load my_file_name.mat
% It will load the img_names variable into variables list. 
% you can check it by typing whos in command window

[Madura Meenakshi Ramamoorthi]

Thanks a lot, it works for me

[arun ghosh]

Dear Madura, The file name"IM000086.jpg" taken by digital camera hp715 & stored in pictures album in my Laptop.I want to transform into dot m(.m) & process as ususal. Would you please help me with step-by-step procedure. Arun ghosh.

[Walter Roberson]

@arun ghosh

That can be done, but what benefit do you see from generating a file of code that hold the content of the image? Your HP715 camera has a maximum resolution of 2048 x 1536 , and is RGB, so that would be over 6000 lines of text that looked like

255,217,218,47,48,53,0,1,0,0,0,3,0,0,58,122,247 (on for a total of 1536 entries)

and would require approximately 2048*1536*3*4 characters, roughly 37 megabytes.

What are your purposes that you want the image converted to .m file?

Wouldn't it be easier to just read in the file every time you needed it?

IM86 = imread('~/Pictures/IM000086.jpg');

I am assuming here from your refrence to "pictures album" that you are using MacOS and the file is stored directly in your Pictures directory... and not, for example, instead stored in your iPhotos album.