>> image = imread('input.jpg')

>> image_rgb = rgb2gray(image)

>> F = fft2(double(image_rgb))

>> imshow(abs(fftshift(F)),[24 100000])

>> RGB = imread('input2.png')

>> I = rgb2gray(RGB)

>> imshow(I)

>> F=fft2(double(I))

>> imshow(abs(fftshift(F)),[24 100000])

>> imshow(angle(fftshift(F)),[-pi pi])

>> FA=abs(F)

>> FB=exp(i*angle(F))

% inverse Fourier transform of FA (magnitude) and FB (phase):

>> IA = ifft2(FA) %image reconstructed using magnitude information

>> IB = ifft2(FB) %image reconstructed using phase information

% iift color ranges have to be set using imshow

>> cmin = min(min(abs(IA)))

>> cmax = max(max(abs(IA)))

>> dmin = min(min(abs(IB)))

>> dmax = max(max(abs(IB)))

>> imshow(abs(IA), [cmin cmax])

%

% imshow works automatically for natural images but for reconstruction, proper color limits should be

% set to display sufficient amount of detail in the image since FFT are infinite.

>> imshow(abs(FB), [dmin dmax])

>> im1 = imread('ariana.jpg')

>> imshow(im1)

% convert the rgb image (if it is) to gray-image.

>> im1 = rgb2gray(im1)

% 64 gray-level image

>> [IM5,map5]=gray2ind(im1,64)

% 16 gray-level image

>> [IM4,map4]=gray2ind(im1,16)

% 8 gray-level image

>> [IM3,map3]=gray2ind(im1,8)

% 4 gray-level image

>> [IM2,map2]=gray2ind(im1,4)

% 2 gray-level image

>> [IM1,map1]=gray2ind(im1,2)

>> figure(2), subplot(221), subimage(im1), title('original'), subplot(222), subimage(IM5,map5),

title('gray-level=64'),subplot(223), subimage(IM4,map4), title('gray-level=16'),subplot(224),

subimage(IM3,map3), title('gray-level=8'),pause

>> figure(3), subplot(221), subimage(im1), title('original'), subplot(222), subimage(IM3,map3),

title('gray-level=8'),subplot(223), subimage(IM2,map2), title('gray-level=4'),subplot(224),

subimage(IM1,map1), title('gray-level=2'),pause

>> im1 = imread(ariana.jpg)

% reduce the resolution by half the original value

>> IMG1 = imresize(im1,0.5)

>> IMG2 = imresize(im1,0.25)

>> IMG3 = imresize(im1,0.125)

>> figure(2), subplot(221), subimage(im1), title('orginal'),subplot(222), subimage(IMG1),

title('/2 resolution'),subplot(223), subimage(IMG2), title('/4 resolution'),subplot(224),

subimage(IMG3), title('/8 resolution'),pause

>> img = imread(dots.jpg)

>> img = grb2gray(img)

>> img1 = im2double(img)

>> mf =ones(5,5)/25 % averaging mask of size 5*5

>> y = filter2(mf,img1)

>> imshow(y)

>> mf =ones(11,11)/121 % averaging mask of size 11*11

>> y = filter2(mf,img1)

>> imshow(y)

>> img = imread(dots.jpg)

>> af=fftshift(fft2(img))

>> [x,y]=meshgrid(-128:127,-128:127)

>>z=sqrt(x.^2+y.^2)

>>c=z> af1=af.*c

>> af1iifft2(af1)

>> ifftshow(af1i)

>> fftshow(af1)

>> img = imread(strips.jpg)

>> af=fftshift(fft2(img))

>> [x,y]=meshgrid(-128:127,-128:127)

>>z=sqrt(x.^2+y.^2)

>>c=z>10

>> af1=af.*c

>> af1iifft2(af1)

>> ifftshow(af1i)

>> fftshow(af1)

>> img = imread(strips.jpg)

>> px=[-1 0 1; -1 0 1; -1 0 1]

>> icx = filter2(px,ic)

>> py=px

>> py =px;

>> icy=filter2(py,ic)

>> pedge = sqrt(icx.^2,icy.^2)

>> imshow(pedge/255)

>> A=imread('ariana.jpg');

>> B=rgb2gray(A);

>> C=double(B);

>> for i=1:size(C,1)-2

for j=1:size(C,2)-2

%Sobel mask for x-direction:

Gx=((2*C(i+2,j+1)+C(i+2,j)+C(i+2,j+2))-(2*C(i,j+1)+C(i,j)+C(i,j+2)));

%Sobel mask for y-direction:

Gy=((2*C(i+1,j+2)+C(i,j+2)+C(i+2,j+2))-(2*C(i+1,j)+C(i,j)+C(i+2,j)));

B(i,j)=sqrt(Gx.^2+Gy.^2);

end

end

>> figure,imshow(B); title('Sobel gradient');

>> a=imread('ariana.jpg');

>> a=rgb2gray(a);

>> b=im2double(a);

>> [m,n]=size(a)

>> N(1:m,1:n)=0

for i=1:m-2;

for j=1:m-2;

N(i,j)=-1*b(i,j)-1*b(i,j+1)-1*b(i,j+2)+0+0+0+1*b(i+2,j)+1*b(i+2,j+1)+1*b(i+2,j+2);

end;

end;

>> O(1:m,1:n)=0

>> for i=1:m-2;

for j=1:m-2;

O(i,j)=-1*b(i,j)+0+1*b(i,j+2)-1*b(i+2,j)+0+1*b(i+1,j+2)-1*b(i+2,j)+0+1*b(i+2,j+2);

end;

end;

>> Z=N+O;

>> imshow(Z);

>> a=imread('ariana.jpg'); >> b=im2double(a); >> [m,n]=size(a); >> L(1:m,1:n)=0 >> for i=1:m-2; for j=1:m-2; L(i,j)=-1*b(i,j)+0+0+1*b(i+1,j+1); end;

end; >> M(1:m,1:n)=0 >> for i=1:m-2; for j=1:m-2; M(i,j)=0-1*b(i,j+1)+1*b(i+1,j)+0; end; end; >> N=M+L; >> imshow(N);