Loop with different images on Matlab

I have a question about how can I create a loop. I'm going to try to simplify. I have three images (the real problem has a huge images). For example:

image1.tif
image2.tif
image3.tif

On the other hand, I have a text file (I cannot introduce this on the code directly) with two different parameters for each image. For example:

Parameterimage1_1= 1.2; %value related to image1
Parameterimage1_2= 2.3; %corresponds to image1
Parameterimage2_1= 5.3; %corresponds to image2
Parameterimage2_2= 2.4; %corresponds to image2
(...)

What I need to do is to read the text file and then, apply two different parameters for each image in a loop to calculate. What I have done is the following:

Image1= imread ('image1.tif');       
Image2= imread ('image2.tif'); 
Image3= imread ('image3.tif'); 

Data= READINGPARAMETERS(parameters)

param1= Data.param1;
param2= Data.param2;
param3=Data.param3;
(...)

Image1_out= param1*Image1/param2;
Image2_out= param3*Image1/param4;
Image2_out= param5*Image1/param6;

imwrite(Image1_out, 'G:\Image1_out.tiff','tiff');
imwrite(Image2_out, 'G:\Image2_out.tiff','tiff');

function [Data] = READINGPARAMETERS(parameters)

fid = fopen(parameters); % I have defined the path previously
text = fscanf(fid, '%c');

posini= strfind(text,'=');
posfin= strfind(text,';');

Datos.param1= str2num(texto(posini(1)+1 : posfin(1)-1));
Datos.param2= str2num(texto(posini(2)+1 : posfin(2)-1));
Datos.param3= str2num(texto(posini(3)+1 : posfin(3)-1));
(...)

return

My question is that I don't know how to create the loop for that and with every image, uses two parameteres. Usually, I do it in that way but I don't know how to indicate that has to take the values.

for k = 1:length(tifFiles)
baseFileName = tifFiles(k).name;
fullFileName = fullfile(myFolder, baseFileName);
fprintf(1, 'Now reading %s\n', fullFileName);
imageArray = imread(fullFileName);

AND here the process

imwrite(imageArray, fullFileName);

Any kind of help would be appreciated,

Greetings,

Answer 1

[Matz Johansson Bergström]

I don't know exactly what you do in the function READINGPARAMETERS, but I would first let the function store the values in a matrix Data instead of the was you describe it (is it a cell?). Say you have 100 images, then the matrix would be 100x2.

Then I would loop through the images something like (I have not tried this)

for i=1:length(tifFiles)
   imageArray = imread(fullFileName);
   out = Data(i,1)*imageArray*Data(i,2);
   imwrite(out, ['G:\', sprintf('Image%d_out.tiff', i)], 'tiff');
end

By the way, is that supposed to be Image1 for each row or Image1, Image2 and Image3?

Image1_out= param1*Image1/param2;
Image2_out= param3*Image1/param4;
Image2_out= param5*Image1/param6;

This is a step on the way I think.

[Emmanuelle]

Thanks a lot Matz. The function readingparameters is with the aim to read some values from a txt file. It would be also fine to read and store in a Matrix, maybe it's easier. I've tried it also but I have a problem with that line:

 out = Data(i,1)*imageArray*Data(i,2);

The problem is the following:

Undefined function 'mtimes' for input arguments of
type 'struct'.

I have changed it on that way:

for i=1:length(tifFiles)

    params = fieldnames(Datos);
    baseFileName = tifFiles(i).name;
    fullFileName = fullfile(dir_entrada, baseFileName);
   imageArray = imread(fullFileName);
   out = Datos(i,1)*imageArray;
   imwrite(out, ['G:\salida\', sprintf('Image%d_out.tiff', i)], 'tiff');
end

And the problem is alwsays on that line:

out = Datos(i,1)*imageArray;

I'm going to check better but thanks because I think it's the way for doing it!

[Matz Johansson Bergström]

Yes readingparameters is returning a struct, so Data will then be a struct, which is not what we want. If you post the complete readingparameters function I can see what is happening.

[Emmanuelle]

Ok!! Here it is:

function [Data] = READINGPARAMETERS(ficherointerc)

fid = fopen(ficherointerc);
texto = fscanf(fid, '%c');
fclose(fid);

posini= strfind(texto,'=');
posfin= strfind(texto,';');

Datos.param1= str2num(texto(posini(1)+1 : posfin(1)-1));
Datos.param2= str2num(texto(posini(2)+1 : posfin(2)-1));
Datos.param3= str2num(texto(posini(3)+1 : posfin(3)-1));
Datos.param4= str2num(texto(posini(4)+1 : posfin(4)-1));

return

[Matz Johansson Bergström]

Ok, I think I know what you want to do now. It seems that the syntax of the file you want to parse is for example

bla bla = 43.235;
bla bla = 6.235;

param1 and param2 should be applied to the first image, param3 and param4 to the next etc. if I understand you correctly.

Then the following should work

function Data= READINGPARAMETERS(parameters)

fid = fopen(parameters);
strs = textscan(fid, '%s = %f;') %strings and floats
Data = zeros(length(strs), 2);

tmp = strs{2}; %pick out the floats

%The parameters are in the columns for each image file
Data(:, 1) = tmp(1:2:end);
Data(:, 2) = tmp(2:2:end);

Now you will have the parameters in a matrix, so you can apply them as previously mentioned. I hope this is what you wanted.

[Emmanuelle]

Thank you so much, it works!