HOW TO MAKE A 2D SINE WAVE

SET SIZE OF IMAGE
X=1:600; 
[Xm Ym]=meshgrid(X, X); 

DEFINE SINE WAVE, SCALED TO IMAGE SIZE AND SO THAT VALUES WORK IN GRAY SCALE

Z=(sin(Xm*2*pi/600)+1)/2+(sin(Ym*2*pi/600)+1)/2

PIC OF SURFACE IN 3D

surf(Xm,Ym,Z)

[need image size to be about 100px for this to look nice, otherwise is just black]

SHOW WAVE FROM ABOVE - CONTOUR STYLE

imshow(Z)

FOR FOURIER TRANSFORM

fftA = fft2(double(Z))
ffB=log(abs(fftshift(fftA)+1))

imshow(ffB)

[FOURIER TRANFORM MOST OBVIOUS IF YOU HAVE SINE WAVES WITH HIGH FREQUENCIES, SAY OVER 10, SO THE BRIGHT PIXELS ARE FAR ENOUGH FROM THE CENTRE]

FOR IMAGE

PIC = imread('/.../.../picture.jpg')

VIEW WITH

imshow(PIC)

TURN INTO GRAYSCALE ARRAY

PIC2=rgb2gray(PIC)

FOR FOURIER TRANSFORM

fftA = fft2(double(PIC)); fftB=log(abs(fftshift(fftA)+1)); fftC=fftB/max(max(max(fftB)));

NEED TO DIVIDE BY MAX ELT OF FFTB TO MAKE GRAYSCALE WORK

VIEW WITH

imshow(fftC)


ROTATE IMAGE WITH

PIC3=imrotate(PIC,45)