imwrite() with PGM option actually write in PBM

Hi all, I am trying to convert DICOM images in PGM images for a software I am using. dicomread() reads them correctly, but when it comes to use imwrite(), it provides PBM images (I check it using Mac infos, and using the fact that on the program I am writing gives me an error when I use those images, a wrong-extension-error). Note that if I try other formats like png it works.

The code is the following:

clear all; close all; clc;

MM = 1686; % maximum value for normalization
mm = -2048; % minimum value

for ii=1:331
    str = strcat('/my/path/IM-0001-',num,'-0001.dcm');  % DICOM image name
    info = dicominfo(str,'UseDictionaryVR',true);       % DICOM info
    Y = double(dicomread(info));                        % read
    Y = (Y-mm)./(MM-mm);                                % normalize
    titleSlice = strcat('/my/path/slice',num2str(ii),'.pgm');  % output name
    imwrite(Y,titleSlice,'pgm');                        % imwrite() which provides PBM and not PGM
end

Answer 1

[KALYAN ACHARJYA]

Follow this way, its works to write the dicom in pgm format

path_directory='dcm_sample_images'; % 'Folder name'
original_files=dir([path_directory '/*.dcm']);
for j=1:3
    filename=[path_directory '/' original_files(j).name];
    I1=double(dicomread(filename));
    %do your findings, say I2 is results
    path_folder='D:\JNU jaipur\PhD\Matlab Work\dicom_write_test';
    baseFileName=sprintf('%d.pgm',j); 
    fullFileName=fullfile(path_folder,baseFileName); % No need to worry about slashes now!
    imwrite(I2,fullFileName);
end