topic Re: How to implement two dimensional short-time Fourier transform ( 2-D STFT), 2-D Gabor filter in the LabVIEW 2019? in LabVIEW
https://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4015029#M1148421
<P>Taking a guess, I wonder if you mean you'd like to consider the simultaneous behaviour of the FFTs of two different physical signals (for example, vibration in X and Y directions, leading to the "2D" mention).</P>
<P> </P>
<P>If so, I think you may still want to use the same VIs, but you'll need to consider how to combine your outputs to give the desired display. Like Bob_Schor said, this might result in a 3D plot.</P>Sun, 16 Feb 2020 12:08:38 GMTcbutcher2020-02-16T12:08:38ZHow to implement two dimensional short-time Fourier transform ( 2-D STFT), 2-D Gabor filter in the LabVIEW 2019?
https://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4014688#M1148285
<P>Dear all,</P>
<P>We have a short-time Fourier transform ( STFT), and Gabor filter VI programs are available in an advanced signal processing toolkit. Similarly, is there any possibility of 2-D STFT and 2-D Gabor filter VI programs in LabVIEW. If we don't have these VI programs in the LabVIEW, How we could proceed to implement these 2-D filters in the LabVIEW cRIO (compact RIO) environment. Anyone can guide me in this problem.</P>
<P> </P>
<P>Thanks and regards</P>
<P>Sukumar.</P>Fri, 14 Feb 2020 12:13:10 GMThttps://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4014688#M1148285NAGINENI2020-02-14T12:13:10ZRe: How to implement two dimensional short-time Fourier transform ( 2-D STFT), 2-D Gabor filter in the LabVIEW 2019?
https://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4014988#M1148406
<P>I know about the Short-Time Fourier Transform of a signal, which is a 2-D plot of the signal spectrum as a function of time (sometimes called Time-Frequency Analysis), and I think there are functions in LabVIEW that can perform this (but it helps to both understand LabVIEW and also Signal Theory), but I've not heard of 2-D STFT (which sounds, to me, like looking at a 3-D representation of how a 2-D Fourier Transform changes as a function of time). I'm pretty sure that here is no LabVIEW function to do this. </P>
<P> </P>
<P>Bob Schor</P>Sat, 15 Feb 2020 23:04:08 GMThttps://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4014988#M1148406Bob_Schor2020-02-15T23:04:08ZRe: How to implement two dimensional short-time Fourier transform ( 2-D STFT), 2-D Gabor filter in the LabVIEW 2019?
https://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4015029#M1148421
<P>Taking a guess, I wonder if you mean you'd like to consider the simultaneous behaviour of the FFTs of two different physical signals (for example, vibration in X and Y directions, leading to the "2D" mention).</P>
<P> </P>
<P>If so, I think you may still want to use the same VIs, but you'll need to consider how to combine your outputs to give the desired display. Like Bob_Schor said, this might result in a 3D plot.</P>Sun, 16 Feb 2020 12:08:38 GMThttps://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4015029#M1148421cbutcher2020-02-16T12:08:38ZRe: How to implement two dimensional short-time Fourier transform ( 2-D STFT), 2-D Gabor filter in the LabVIEW 2019?
https://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4015047#M1148430
<P>Thank you so much for your advice.</P>
<P>Is it possible to implement a time-frequency analysis for a 2-D signal (images) in the LabVIEW environment?. kindly share your views about this problem. Incase if possible, what is the better approach to computing a time-frequency analysis for images (2-D signal)?</P>Sun, 16 Feb 2020 15:14:01 GMThttps://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4015047#M1148430NAGINENI2020-02-16T15:14:01ZRe: How to implement two dimensional short-time Fourier transform ( 2-D STFT), 2-D Gabor filter in the LabVIEW 2019?
https://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4015066#M1148442
<BLOCKQUOTE><HR /><LI-USER login="NAGINENI" uid="636961"></LI-USER> wrote:<BR />
<P>Is it possible to implement a time-frequency analysis for a 2-D signal (images) in the LabVIEW environment?. kindly share your views about this problem.</P>
<HR /></BLOCKQUOTE>
<P>I would say that it is <U>possible</U> (as you can certainly <U>state</U> the problem, and can come up with an algorithm that allows you to do the computation), but <U>displaying</U> the result may give you some problems, as you need to create a plot in four dimensions (hard to do on our present 2D display devices).</P>
<P> </P>
<P>To explain: Consider a 1D signal whose spectrum you wish to know. You do an FFT, and produce a 2D plot of Amplitude (or sometimes Power) as a function of Frequency. Now you want to ask "How does the Spectrum vary over Time?", so you do something like a Short Time Fourier Transform and let Time be one of your variables, resulting in a 3D plot with Time and Frequency being the independent variables and Amplitude (or Power) being the dependent variable. This is often plotted as an Intensity Graph, with Time on the X axis, Frequency on the Y, and Intensity as the Z axis for Amplitude/Power.</P>
<P> </P>
<P>Now you want to do the same thing for a 2D Transfer function of an Image, which starts out as a 3D plot, with two Spatial Frequencies as the X and Y axes and Amplitude/Power typically plotted as Z/Intensity. How are you going to show Time? One way, of course, is to make a Video and let Time be "time". Keep Spatial Frequencies "isolated" from Time. For example, suppose you are acquiring Videos at 30 images/second. Take each Image and do a 2D transform of it, creating a 2D Intensity "Image", and save these Images in an AVI file that you can view at 30 images/second.</P>
<P> </P>
<P>Bob Schor </P>Sun, 16 Feb 2020 18:08:55 GMThttps://forums.ni.com/t5/LabVIEW/How-to-implement-two-dimensional-short-time-Fourier-transform-2/m-p/4015066#M1148442Bob_Schor2020-02-16T18:08:55Z