create parallel lines in the same pic and find the average of all the ffts in it

Hello everyone i have a code which draws a line in a pic and takes the fft of the profile of the line,does anyone know how can i take multiple parallel lines to the original line and find the ffts of all the profiles of the pixels and find the averge fft?

Answer 1

[Matt J]

Could you imrotate() the image so that it's rows are parallel to your line? Then, the operation would reduce to

fft( mean( imrotate(yourImage,angle) ,1) )

[george korris]

so for example if i want to rotate the image 30 deggres and want to take the pixels along the rows this would work? I dont need to use improfile or anything else to get the pixels ?

clc;
clear all;
img = imread('1.jpg');
img=imcrop(img)
X=fft( mean( imrotate(img,30) ,1) )
Y = abs(X);
plot(Y);

[george korris]

i get this error when i try that code

Error using plot

Data cannot have more than 2 dimensions.

Error in aa (line 7)

plot(Y);

[Matt J]

If the error is coming from a plot command it is unlikely that it is related to my suggestion, which contains no plot commands..\

[george korris]

yes you are corect what do you think about this:

so for example if i want to rotate the image 30 deggres and want to take the pixels along the rows this would work? I dont need to use improfile or anything else to get the pixels ?

clc;
clear all;
img = imread('1.jpg');
img=imcrop(img)
X=fft( mean( imrotate(img,30) ,1) )

[Matt J]

That's right.

[george korris]

thank you for your time Matt!!

have a nice day!

[george korris]

sorry to bother you again matt but when using that comand where you calculate the fft of the rotated image is it calculating the fft of the background black pixels that imrotate creates or is it taking into considaration only the pixels of the image?

[Matt J]

It is taking the FFT of the average row. The averaging does not distinguish between foreground and background.

Answer 2

[Matt J]

The operation sounds the same, up to a scale factor, as doing

fft(radon(yourImage,theta))

[george korris]

thank you so much Matt for your answer , so this line is calxulating all the ffts of the lines in a specific angle theta?

[Matt J]

It is summing along a direction theta, then taking the fft, but that is essentially the same thing.