stereoParamsINI = helperReadINI("stereoParams.ini");

cameraParams1 = stereoParamsINI.narrow_stereo_left;
cameraParams2 = stereoParamsINI.narrow_stereo_right;

translationOfCamera2 = cameraParams2.projection(:,end);

rotationOfCamera2 = cameraParams2.rectification*cameraParams1.rectification';

intrinsicMatrix1 = cameraParams1.camera_matrix;
intrinsicMatrix2 = cameraParams2.camera_matrix;

distortionCoefficients1 = cameraParams1.distortion;
distortionCoefficients2 = cameraParams2.distortion;

imageSize = [stereoParamsINI.image.height stereoParamsINI.image.width];

stereoParametersObj = stereoParametersFromOpenCV(intrinsicMatrix1, ...
    distortionCoefficients1,intrinsicMatrix2,distortionCoefficients2, ...
    rotationOfCamera2,translationOfCamera2,imageSize);

% Load the image pair.
imageDir = fullfile(toolboxdir('vision'),'visiondata','calibration','stereo');
leftImages = imageDatastore(fullfile(imageDir,'left'));
rightImages = imageDatastore(fullfile(imageDir,'right'));
I1 = readimage(leftImages,1);
I2 = readimage(rightImages,1);

% Rectify the image pair.
[J1,J2] = rectifyStereoImages(I1,I2,stereoParametersObj,OutputView='full');

% Display the results.
figure
J = stereoAnaglyph(J1,J2);
imshow(J)

function cameraParams = helperReadINI(filename)
% helperReadINI reads a ROS INI file, filename, and returns a structure with
% these fields: image, <camera_name1>, <camera_name2>. image is a
% structure describing the height and width of the image captured by the
% cameras of the stereo pair. The fields <camera_name1> and <camera_name2>
% are structures named after the camera names present in the INI file, and they contain
% these fields: camera_matrix, distortion, rectification_matrix,
% and projection_matrix. These fields are stored in the INI file with their
% values placed in a new line followed by their name.

    f = fopen(filename,'r');
    sectionName = '';
    
    while ~feof(f)
        % Read line from file.
        line = fgetl(f);

        % Trim leading and trailing whitespaces.
        line = strtrim(line);
        
        if isempty(line) || line(1)=='#'
            % Skip empty line and comments.
            continue
        elseif line(1) == '[' && line(end) == ']'
            % Identify section names and continue reading.
            sectionName = line(2:end-1);
            sectionName = strrep(sectionName,'/','_');
            continue
        end

        % Replace blankspaces with underscores to create valid MATLAB variable
        % name.
        name = line;
        name(name == ' ') = '_';
        
        % Read the value data in upcoming lines.
        value = [];
        while ~feof(f)
            line = fgetl(f);
            line = strtrim(line);

            if isempty(line)
                % A empty line indicates end of value data.
                break
            elseif line(1)=='#'
                % Skip comment lines.
                continue
            end
            line = str2num(line); %#ok
            value = [value; line]; %#ok
        end
    
        % Store post-processed value.
        if isempty(sectionName)
            cameraParams.(name) = value;
        else
            cameraParams.(sectionName).(name) = value;
        end
    end
    
    fclose(f);
end