Bit Plane Slicing in MATLAB

       Read fractal.jpg file. Display individual bits as binary image. Display and comment on the result.  (Hint: use bitget built-in function)

CODE:

clc; clear;

A=imread('fractal.jpg');

[row,col]=size(A);

subplot(3,3,1), imshow(A), title('Original Image');

C=zeros(row,col,8);

for k=1:8

    for i=1:row

        for j=1:col

            C(i,j,k)=bitget(A(i,j),k);        %Bit slicing

        end

    end

    subplot(3,3,k+1), imshow(C(:,:,k)), title(['Bit Plane ',num2str(k-1)]);

end

OUTPUT RESULT :

We observe that the three higher order planes, especially the 8^th bit plane, contain a significant amount of the visually significant data. The lower order planes contribute to more subtle intensity details in the image. Decomposing an image into its bit planes is useful for analyzing the relative importance of each bit in the image and is useful for image compression.

Gray Level Slicing in MATLAB

 Gray Level Slicing: High-light specific range of gray values without background and with background.

       Read kidney.tif file. Enter lower and upper threshold value from the user. Apply gray level slicing with and without background. Display the result.

 CODE:

clc; clear all;

i=imread('kidney.tif');          % should be graylevel image

j=double(i);

k=double(i);

[row,col]=size(j);

T1=input('Enter the Lowest threshold value:');

T2=input('Enter the Highest threshold value:');

for x=1:row            

    for y=1:col        

        if((j(x,y)>T1) && (j(x,y)<T2))

            j(x,y)=i(x,y);

            k(x,y)=255;

        else

            j(x,y)=0;

            k(x,y)=0;

        end

    end

end

subplot(311), imshow(i), title('Original image')   

subplot(312), imshow(uint8(j)), title('Graylevel slicing with background')

subplot(313), imshow(uint8(k)), title('Graylevel slicing without background')

OUTPUT RESULT:

How to apply Threshold to an image in MATLAB ?

Exercise: Apply thresholding to the original image such that r₁= r₂=mean gray level. Display the result. (Hint: use built-in function im2bw.)

 CODE:

clc; clear all;

%% Reading an image

a1=imread('contrast.jpg');

a=double(a1);

[row,col]=size(a);

%% Calculating mean gray level

sum = 0;

for i=1:row

    for j=1:col

        sum=sum+a(i,j);

    end

end

avg=sum/(row*col);

%% Transformation function

t=0:255;

x1=0*(t>=0 & t<avg); 

x2=255*(t>=avg & t<=255);

x=x1+x2;

%% Obtaining contrast stretched image

for n=1:row

    for m=1:col

        out(n,m)=x(a1(n,m)+1);

    end

end

out1=im2bw(a1);

plot(x)

grid on;

xlabel('Intensity in input image');

ylabel('Intensity in output image')

title('Transformation function')

figure()

subplot(311), imshow(a1), title('Original image')

subplot(312), imshow(uint8(out)), title('Thresholding(using code)')

subplot(313), imshow(out1), title('Thresholding(using im2bw)')

OUTPUT RESULT:

Transformation Function

Perform Arithmetic operations on an Image

Exercise 1) Write a MATLAB program to perform the following.

1)     Read cameraman.tif and rice.png image and display the image

2)     Add the two images and display.

3)     Subtract the two images and display

4)     Add a constant value of 50 to one of the images and display

5)     Subtract a constant value 100 from one of the images and display.

6)     Obtain negative of one of the image. (Subtract 255 from the image) and display.

Create a binary image of size 256 x 256 as shown below and save as ‘mask.tif 

                8)Perform I= uint8(I1).*uint8(M)  ,where I1 is cameraman.tif and M is mask.tif 

                    Images.

clear

close all;

a=imread('cameraman.tif');

b=imread('rice.png');

c=a+b;                  % addition

d=a-b;                  % subtraction

e=a.*b;                 % multiplication

f=b+50;                % adding a constant

g=a-100;              % subtracting a constant

h=255-b;              % negative of a image

%% creating a mask and saving it

i=zeros([256 256]);

j = 64:192;

k = 64:192;

i(j,k) = i(j,k)+1;

imwrite(i,'mask.tif');

l=uint8(a).*uint8(i);

subplot(331),imshow(a),title('Image 1')

subplot(332),imshow(b),title('Image 2')

subplot(333),imshow(c),title('Addition')

subplot(334),imshow(d),title('Subtraction')

subplot(335),imshow(e),title('Multiplication')

subplot(336),imshow(f),title('Adding a constant(50) to Image 2')

subplot(337),imshow(g),title('Subtracting a constant(100) from Image 1')

subplot(338),imshow(h),title('Negative of Image 2')

subplot(339),imshow(l),title('Masking of Image 1')

Fig 1. Arithmetic operations on image using code

Exercise 2) Write the above program using imadd() function for addition, imsubtract() for Subtraction, immultiply() for multiplication operations. Use imcomplement() function to get complement of an image.

clear

close all;

a=imread('cameraman.tif');

b=imread('rice.png');

c=imadd(a,b);                   % addition

d=imsubtract(a,b);           % subtraction

e=immultiply(a,b);                         % multiplication

f=imadd(b,100);                              % adding a constant

g=imsubtract(a,50);                        % subtracting a constant

h=imcomplement(b);                     % complement of image

subplot(331),imshow(a),title('Image 1')

subplot(332),imshow(b),title('Image 2')

subplot(333),imshow(c),title('Addition')

subplot(334),imshow(d),title('Subtraction')

subplot(335),imshow(e),title('Multiplication')

subplot(336),imshow(f),title('Adding a constant(100) to Image 2')

subplot(337),imshow(g),title('Subtracting a constant(50) from Image 1')

subplot(338),imshow(h),title('Complement of Image 2')

Fig. 2: Arithmetic operations on image using built-in functions