encoding_gui.m

classdef encoding_gui < handle
    %ENCODING_GUI() - Creates a minimalistic GUI for easy encoding.
    % This function will create and handle a simple GUI in order to encode
    % images. Encoding will be done using the enhanced run length encoding
    % recommended by the DLPC900 Programming Guide. The encoding is done by
    % using functions from Klaus Huecks DMDConncet library.
    %
    % Syntax: encoding_gui()
    %
    % Input:
    %       none
    %
    % Output:
    %       none
    %
    % Author: Hannes Suhr, credits to Klaus Hueck
    % Hochschule Aalen
    % Email address: hannes.suhr@studmail.htw-aalen.de
    % Website: -
    % June 2020; Last revision: 09-June-2020
    
    properties (Access = private)
        guiFigure;                  % the figure handle
        directory_button;           % select directory button
        encoding_button;            % start encoding button
        textField;                  % text field to show status
        encoded;                    % encoded data
        files;                      % image files to encode
        directoryName;              % directory name to save encoded
        fontSize = 11;              % font size of the gui
        encodedFileName =...        % name of file with encoded data
            'encoded_images.txt';
    end
    
    methods
        function obj = encoding_gui()
            % CREATEGUI - Creates Gui object
            
            obj.guiFigure = figure('Name','Encode Images','DockControls',...
                'off',...
                'Visible','off','Position',[500,500,450,100],...
                'MenuBar','none');
            % Start the gui
            obj.createWidgtes();
        end
        
        function obj = createWidgtes(obj)
            %CREATEWIDGETS - Constructs the Gui widgets.
            
            obj.directory_button = uicontrol('Style','pushbutton',...
                'String','Directory',...
                'Position',[10,10,90,90],...
                'Callback',{@obj.directory_button_Callback},...
                'FontSize',obj.fontSize);
            
            obj.encoding_button = uicontrol('Style','pushbutton',...
                'String','Encode',...
                'Position',[100,10,90,90],...
                'Callback',{@obj.encoding_button_Callback},...
                'FontSize',obj.fontSize);
            
            obj.textField = uicontrol('Style','text','Position',...
                [200,10,180,70]);
            
            align([obj.directory_button, obj.encoding_button,...
                obj.textField],'distribute','bottom');
            obj.guiFigure.Visible = 'on';
        end
        
        function directory_button_Callback(obj, ~, ~)
            %DIRECTORY_BUTTON_CALLBACK - Button function fetching the directory.
            
            % get the directory name
            obj.directoryName = uigetdir('./',...
                'Select Image Directory For Encoding');
            
            % get all images with the specified extensions from directory
            obj.files = dir(join([obj.directoryName,'/*.bmp']));
            
            % show how many images where found
            obj.updateTextField(sprintf('Found %d images.\n',...
                length(obj.files)));
            
            % create cell array based on the number of cells found
            obj.encoded = cell(length(obj.files)*2,1);
        end
        
        function encoding_button_Callback(obj, ~, ~)
            %ENCODING_BUTTON_CALLBACK - Button function, encodes the images and
            %saves them.
            filePath = join([obj.directoryName,'/',obj.encodedFileName]);
            fid = fopen(filePath,'w');
            fprintf(fid,'First Line is always ignored\n');
            fclose(fid);
            
            % for each image, do encoding & save it in the
            tic;
            for iFiles = 1:1:length(obj.files)
                
                % update textbox in gui
                obj.updateTextField(sprintf('encode image %s %d',...
                    obj.files(iFiles).name,iFiles));
                
                % get full image name
                imageName = join([obj.directoryName,'/',...
                    obj.files(iFiles).name]);
                image = imread(imageName);
                obj.encoded{iFiles*2-1} = join(obj.files(iFiles).name,...
                    '\n');
                obj.encoded{iFiles*2} = enhancedRLE(8,image);
                
                fid = fopen(filePath,'a');
                fprintf(fid,'%s,\n', obj.encoded{iFiles*2-1});
                fprintf(fid,'%d, ', obj.encoded{iFiles*2});
                fprintf(fid,'\n');
                fclose(fid);
                
            end
            
            obj.updateTextField(sprintf(...
                'Encoding done after %.3f [s]. Saved Encoding in %s.',...
                toc,obj.encodedFileName));
        end
        
        function updateTextField(obj, formattedText)
            %UPDATETEXTFIELD - Shows the current status in the Gui.
            
            set(obj.textField,'String',formattedText);
            set(obj.textField,'FontSize',obj.fontSize);
            drawnow;
            disp(formattedText)
        end
    end
    
end

function encoded_string = enhancedRLE(bitDepth, bitmap)
%enhancedRLE compresses a bitmap.
% enhancedRLE uses the enhance run length encoding according ot the DLPC900
% programming guide, and attaches the needed header file to the compressed
% data.
%
% Syntax: encoded_string = enhancedRLE(bitDepth, bitmap)
%
% Input:
%       bitDepth -  The bit depth that is used to encode the image. It
%                   should be set to the bit depth of the images.
%       bitmap   -  The bitmap that we encode as a matrix.
%
% Output:
%       encoded_string  -   The encoded data as a string. each byte is
%                           represented in hexadecimal.
%
% The RLE algorithm is based on http://stackoverflow.com/questions/
% 12059744/run-length-encoding-in-matlab
%
% Author: Klaus Hueck (e-mail: khueck (at) physik (dot) uni-hamburg (dot) de)
% Version: 0.0.1alpha
% Changes tracker:  28.01.2016  - First version
% License: GPL v3
%
% This function was copied from the DMDConnect library from Klaus Hueck.
% Repository: https://github.com/deichrenner/DMDConnect
% DOI: 10.5281/zendo.45713

signature = ['53'; '70'; '6C'; '64'];
imageWidth = dec2hex(typecast(uint16(size(bitmap,2)),'uint8'),2);
imageHeight = dec2hex(typecast(uint16(size(bitmap,1)),'uint8'),2);
numOfBytes = dec2hex(typecast(uint32(size(bitmap,1)*size(bitmap,2)*...
    bitDepth),'uint8'),2);
backgroundColor = ['00'; '00'; '00'; '00'];
compression = '02';

header = [signature; imageWidth; imageHeight; numOfBytes; ...
    'FF'; 'FF'; 'FF'; 'FF'; 'FF'; 'FF'; 'FF'; 'FF'; backgroundColor; ...
    '00'; compression; '01'; '00'; '00'; '00'; '00'; '00'; '00'; '00';...
    '00'; '00'; '00'; '00'; '00'; '00'; '00'; '00'; '00'; '00'; '00';...
    '00'; '00'; '00'];

% convert input matrix to decimal and transpose for later handling
bitmap = bitmap'*1;

% expand to 24bit in 3x8bit decimal notation
BMP24 = dec2hex(bitmap(:),6);

% clear return variable
[szy, szx] = size(bitmap);
encoded_string = '';
%encoded_string = strings(1,imageWidth*imageHeight);
%encoded_string = repmat('a',1,szx*10);

% reshape in order to get 24bit pixel information line by line
for i = 1:szx
    [~, ~, ic] = unique(BMP24((i-1)*szy+1:i*szy,:), 'rows');
    ind = find(diff([ic(1)-1, ic(:)']))+(i-1)*szy;
    relMat = [formatrep(diff([ind, i*szy+1])), BMP24(ind,:)];
    encoded_string = [encoded_string sprintf(relMat(:,:)')];
    %encoded_string(1,1+(i-1)*10:i*10) = sprintf(relMat(:,:)');
end
encoded_string = [header; char(regexp(encoded_string,...
    sprintf('\\w{1,%d}', 2), 'match')'); '00'; '01'; '00'];
encoded_string = hex2dec(encoded_string);
end


function x = formatrep(n)
%FORMATREP returns the eRLE repetition number n in required format.
% According to the DLPC900 programmers guide p.64, the repetition byte n for
% the enhanced run length encoding has to be in the form
% n < 128  : x = n
% n >= 128 : x = [(n & 0xfF ) | 0x80, (n >> 7)]
% here, &, | and >> are the corresponding operators in C syntax.
% Be careful, the example featured in the programmers guide seems to be
% wrong!
% For reference and to play around you can use the following C code:
% #include <stdio.h>
% int main()
% {
%     int x = 0;
%     int y = 0;
%     int z = 500;
%     x = ( z & 0x7F ) | 0x80;
%     y = z >> 7;
%     printf("%x, %x \n", x & 0xff, y & 0xff);
%     printf("%d, %d \n", x, y);
%     return 0;
% }
%
% Syntax: x = formatrep(n)
%
% Input:
%       n -  The repetition number, when encoding.
%
% Output:
%       x -  The repetition number in the correct format.
%
% Author: Klaus Hueck (e-mail: khueck (at) physik (dot) uni-hamburg (dot) de)
% Version: 0.0.1alpha
% Changes tracker:  28.01.2016  - First version
% License: GPL v3
%
% This function was copied from the DMDConnect library from Klaus Hueck.
% Repository: https://github.com/deichrenner/DMDConnect
% DOI: 10.5281/zendo.45713

if n < 128
    x = dec2hex(n, 2);
else
    x1 = dec2hex(bitor(bitand(n,127), 128), 2);
    x2 = dec2hex(bitshift(n, -7), 2);
    x = [x1, x2];
end

end