IMAGE PROCESSING

Paint Application using bwlabel concept

Fill the image with RGB colors based on user specified color value. Instead of Flood fill algorithm I am using bwlabel function in MATLAB to paint the image.

This is very simple comparing to the previous application.


function color

global BW L A colorv rgb originalcolor undocolor point filename;



scz=get(0,'ScreenSize');

figure('Position',[round(scz(1,3)/4) round(scz(1,4)/8) 700 500],'MenuBar','None','NumberTitle','off','Name','Paint Application','Resize','off');

originalcolor=[0;0;0;];

ax=axes('Position',[0 0 .7 1],'xtick',[],'ytick',[]);

directory=dir('*.png');

files={directory.name}';

uicontrol('Style','popupmenu','position',[535 430 160 30],'Value',1,'String',files,'Callback',@displayfile);




uicontrol('Style','text','position',[495 400 35 20],'String','RED');


R=uicontrol('Style','slider', 'position',[535 400 160 20],'min', 0.0, 'max',1.0,'Callback',@colorvalue);


uicontrol('Style','text','position',[495 360 35 20],'String','GREEN');

G=uicontrol('Style','slider', 'position',[535 360 160 20],'min', 0.0, 'max',1.0,'Callback',@colorvalue);


uicontrol('Style','text','position',[495 320 35 20],'String','BLUE');
B=uicontrol('Style','slider', 'position',[535 320 160 20],'min', 0.0, 'max',1.0,'Callback',@colorvalue);


uicontrol('Style','text','position',[495 280 35 20],'String','Color');

colorv(25,80,1:3)=0;


uicontrol('Style','pushbutton','position',[600, 470, 40,20],'String', 'UNDO','Callback',@options);

uicontrol('Style','pushbutton','position',[645, 470, 40,20],'String', 'SAVE','Callback',@options);

uicontrol('Style','pushbutton','position',[540 280 80 30]);

Function ‘colorvalue’ will show the color on the pushbutton.


function colorvalue(obj,event)








        R1=get(R,'value');

        G1=get(G,'value');

        B1=get(B,'value');

        rgb=[ceil(R1*255); ceil(G1*255); ceil(B1*255);];

        colorv(:,:,1)=R1;

        colorv(:,:,2)=G1;

        colorv(:,:,3)=B1;

uicontrol('Style','pushbutton','position',[540 280 80 30],'String','color','CDATA',colorv);

  originalcolor=rgb;

  try

 paintme;

  catch

      originalcolor='null';

  end

    end

%User selects the image


function displayfile(obj,event)

        ptr=get(obj,'value');

        filename=char(files(ptr));

        A=imread(filename);

        [BW,L]=bwlabel(im2bw(A),8);

        imshow(BW);

end







    function paintme


        while(originalcolor==rgb)

            getpoints;

       end

    end

%To save the image or to go back to the previous point


function options(obj,event)

        fn=get(obj,'String');

        if(strcmp(fn,'SAVE')==1)

            fname=strcat('my',filename);

           msg=strcat('File name:',fname);

           msgbox(msg,'FILE SAVED');

        elseif(strcmp(fn,'UNDO')==1)

            rgb=undocolor;

            colorfill(point(1),point(2));

            rgb=originalcolor;

       end

    end

%Get the point in the image.


function getpoints

     try

         waitforbuttonpress;

         f=get(ax,'CurrentPoint');

         x=round(f(1,2));

         y=round(f(1,1));

        if(x< size(A,1) && y < size(A,2))

          %Check whether x and y are less than the image size

         point(1)=x;

         point(2)=y;

         undocolor=[A(x,y,1); A(x,y,2); A(x,y,3);];

         colorfill(x,y);

        end

     catch

        originalcolor='null';

     end

end

%Fill the image with the RGB value



function colorfill(x,y)

        label=BW(x,y);

        [r c]=find(BW==label);

         for i=1:size(r,1)

            A(r(i,1),c(i,1),:)=rgb;

        end

        imshow(A);

    end

end

Watch the video: Painting the image using MATLAB.

GET THE SAMPLE IMAGE AT:http://www.clker.com/clipart-jumping-horse-outline.html

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Array Search

Let's search the cell array and find the index. This simple example will help to find the index in cell array of large size.

names={'Hilda' 'Helen' 'Ada'; 'Matthew' 'Jenny' 'Justin'; 'Agnes' 'Merlin' 'Mark';}

names =

'Hilda' 'Helen' 'Ada'

'Matthew' 'Jenny' 'Justin'

'Agnes' 'Merlin' 'Mark'

I need to know whether the name 'Justin' exists in this cell array

find(strcmp(names,'Justin')==1)

ans =

Let me retrieve the name 'Justin' , using the index

names{8}

ans =

Justin

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Adding elements to a 2d array

A=[100 230 11; 22 10 15; 2 3 90;]

A =

100 230 11

22 10 15

2 3 90

To add a row at the beginning:

A=[[10 20 30]; A]

A =

10 20 30

100 230 11

22 10 15

2 3 90

To add a row at the end:

A=[A; [10 20 30];]

A =

100 230 11

22 10 15

2 3 90

10 20 30

To add a column at the beginning:

A=[[10; 20 ;30] A]

A =

10 100 230 11

20 22 10 15

30 2 3 90

To add a column at the end:

A=[A [10; 20 ;30]]

A =

100 230 11 10

22 10 15 20

2 3 90 30

To add a row in the middle:

A=[10 12 14 16; 3 6 9 12; 4 8 12 16; 5 10 15 20;]

A =

10 12 14 16
3 6 9 12
4 8 12 16
5 10 15 20

A=[A(1:2,:); [8 16 24 32]; A(3:4,:);]

A =

10 12 14 16
3 6 9 12
8 16 24 32
4 8 12 16
5 10 15 20

To add a column in the middle:

A=[A(:,1:2) [100; 200; 300; 400;] A(:,3:4)]

A =

10 12 100 14 16
3 6 200 9 12
4 8 300 12 16
5 10 400 15 20

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Tiling effect in MATLAB

Tiling effect

original Image

Let’s make some random rectangles from the image.

MATLAB CODE:

A=imread('tulip2.jpg');

C=uint8(zeros(size(A)));

i=1; j=1;

col=0;

row=0;

m=1;n=1;

%change the rsz and csz value to obtain pieces in different sizes

rsz=15;

csz=36;

%change the tsz_row and tsz_col values to make some gaps between the pieces.

tsz_row=3;

tsz_col=5;

while ( i < size(A,1))
%check whether i is less than size of (A,1)

while(m+i+row < size(A,1)&& n+j+col < size(A,2))

%size of the tiles varies depending upon the random number

C(m+i:m+i+row,n+j:n+j+col,:)=A(i:i+row,j:j+col,:);

m=ceil(rand(1)*tsz_row);

n=ceil(rand(1)*tsz_col);

col=ceil(rand(1)*csz);

row=ceil(rand(1)*rsz);

j=j+col;

end

i=i+row;

j=1;

end

figure,imshow(C);

With small gaps

With Large gaps

SEE ALSO : Oil Painting Swirl effect Cone effect Glassy effect Paint application

Subscribe to 'Image processing' to get the complete code.

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Array sorting in MATLAB

Sorting an array and retrieving the minimum and maximum values with the index may seem simpler but this helped me in many ways especially when working with arrays. So this is just a refresh on how to sort a 1 and 2d arrays.

Single dimensional array sorting

To sort the array and display the position (index):

A = [5 8 9 10 100 7 50 8 88 6;];

Before sorting:

A = 5 8 9 10 100 7 50 8 88 6

[sorted_array,pos]= sort(A)

After sorting: Here the sorted array and the array position of each value will be displayed.

By default, sorting type is ‘ascending’.

sorted_array = 5 6 7 8 8 9 10 50 88 100

pos = 1 10 6 2 8 3 4 7 9 5

To find the maximum value:

A = 5 8 9 10 100 7 50 8 88 6

[max_value,max_pos]=max(A)

max_value = 100

max_pos = 5

To find the minimum value:

A = 5 8 9 10 100 7 50 8 88 6

[min_value,min_pos]=min(A)

min_value = 5

min_pos = 1

Two dimensional array sorting:

B=[17 5 8 9; 45 23 50 6; 7 49 21 11]

Before sorting:

B = 17 5 8 9

45 23 50 6

7 49 21 11

[sorted_array, pos]=sort(B(:))

After sorting:

sorted_array =

pos =

Maximum value:

[sorted_array, pos]=max(B(:))

sorted_array =

pos =

Minimum Value:

[sorted_array, pos]=min(B(:))

sorted_array =

pos =

To retrieve the minimum value: B(4)

ans = 5

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