Analysing frequency components

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Jim
Jim 2012-5-22
Hi,
which frequency components are responsible for texture in an image?
I heard lot of people saying high frequency components are resposible for texture in an image
But how?
I cannot find anything except complex values and spectrum by using fft2 command
How this can be analysed from the fft
Can anybody suggest something about this?
Thanks in advance

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回答（2 个）

Walter Roberson
Walter Roberson 2012-5-23
Why don't you construct an artificial image and start playing?
bar = zeros(64,64,'uint8');
bar(:) = 128;
bar(:,10:10:end) = 255;
bar(10:10:end,:) = 255;
colormap(gray(256));
imagesc(bar);
Now you can start exploring the fft() and fft2() properties with a "best-case" image.
foo = fft2(bar);
DC = foo(1,1);
foo(1,1) = 0;
imagesc(real(foo));
What do you see? Can you explain why?
Image Analyst
Image Analyst 2012-5-23
Yeah but that lot of people may not know what they're talking about, or you may have oversimplified what they said. We talked about this before, remember? Remember when I explained how periodic texture will show up as periodic patterns (i.e. spikes) in the spectrum. Walter's suggestion of playing around with different images to see their spectrum is a good one.

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