Some image and audio compression like PNG or FLAC no use this method but replace same data value with shorter version. Compression no equal JPEG, mp3, or ogg but can store all data exact.
@oussamalaouadi8521
4 жыл бұрын
Great. Thank You so much. just one thing to point out : the JPEG Compression standard used the DCT transform on the block level of an image (usually 8x8) it's based on Fourier's idea but a bit advanced in some sense that it de-correlates the input data (frequency information of pixels) to make it easier to Quantify (reduce) the higher frequencies and still get almost the same image with less volume.
@chowdhsk
2 жыл бұрын
yes was just about to type this. @steve maybe you should mention it
@OliverKhan-p2e
Жыл бұрын
Excellent video. It was especially interesting to understand image compression in the context of Parseval's Theorem.
@gammingfatma2282
3 жыл бұрын
أستاذ رائع ومميّز.... Great Video
@SRIMANTASANTRA
4 жыл бұрын
Hi Professor Steve, Thanks.....
@astrovenky
4 жыл бұрын
7:05 this doesn't have to be true but this is true!! Lol 🤣
@sksahil4374
Жыл бұрын
Great Video. Very good explanation. it's clear my concept about wavelet transformation.
@alexeyl22
4 жыл бұрын
Would be nice to see effects of various animations on the FFT.
@johnwt7333
3 жыл бұрын
Just do it yourself in python.
@FengXingFengXing
Ай бұрын
This video have FFT history and animación: m.kzitem.info/news/bejne/z6OdrHttiYd5maQ
@xiezhang1741
4 жыл бұрын
I am curious how the "transparent" board works.
@danielsteel5251
4 жыл бұрын
Likely some variation on this: black room, solid color background, special neon markers, camera behind *pane of glass,* and the picture is reversed (i.e., horizontally reflected) either before or after recording. Make sense?
@xiezhang1741
4 жыл бұрын
@@danielsteel5251 Thanks. That explains. Sometimes he also includes his computer screen on the board. Guess there would be another projector involved. Anyways, it's really cool to see it. It looks so nice.
@danielsteel5251
4 жыл бұрын
@@xiezhang1741 _... Guess there would be another projector involved. ..._ I'd guess that it was video editing, after the fact; not a projector.
@xiezhang1741
4 жыл бұрын
@@danielsteel5251 That's unlikely, since he is precisely pointing to the right codes and images while he demonstrates the code implementations. It's gonna be really difficult to pretend something exists there while explaining very accurately and add the actual stuffs later.
@superuser8636
4 жыл бұрын
@@xiezhang1741 His screen is being recorded and he can see it in a monitor while recording as he can be seen looking off camera into a monitor and it is then later edited in (and out) in post-production (post/post-prod) as necessary. If I'm wrong feel free to offer an alternate theory, but this seems the most likely and is what I would do.
@lernenmitrobin
4 жыл бұрын
Great Steve! There was the Parsevals theorem related to FFT we talked about a few videos ago. Very nice example and explanation!!!
@bryanperf
4 жыл бұрын
Another great video and well explained. Doesn't JPEG use the DCT instead of the full FFT?
@supershaye
4 жыл бұрын
Yes JPEG uses the DCT instead. The energy compaction of the DCT is much better than the Fourier Transform.
@Miyelsh
4 жыл бұрын
JPEG uses the DCT with blocks of pixels instead of the whole image at once. That's why badly jpg'd images have the odd blocky appearance.
@individuoenigmatico1990
8 ай бұрын
Wonderful content. I think the fact that compression works depends on the fact that the Discrete Fourier Transform, and hence its inverse, are unitary operators, hence they preserve distances between vectors. If I am eliminating a little noise in a vector in the Fourier space, I get a new denoised vector whose distance to the first one is negligible, hence the distance between the original image and the the "compressed" image shall itself be negligible.
@EEDKonduruLakshmiBhanuPrakashR
4 жыл бұрын
Professor can you please explain difference between and FFT and DCT, why DCT is used in JPEG Compression and can you please explain python code for JPEG COMPRESSION . Thank you.
@michaeljurado7224
2 жыл бұрын
This is a great video.
@falahmohsen9796
2 жыл бұрын
hello >>>thank you for this فhe interesting lecture. Can I communicate with you by email about the same topic
@migueMSD
3 жыл бұрын
Great video
@Eigensteve
3 жыл бұрын
Thanks!
@ashwinsrinivas7278
4 жыл бұрын
Peppa!!! What are you doing in Steve's video??
@amortalbeing
3 ай бұрын
Thanks good
@konstantinosmimidis1632
4 жыл бұрын
Great video. Very good level of explanation for educational purposes, but also for professionals. Congratulations! Looking forward for the wavelet analysis and S-transform if it possible sometime.
@Amine-gz7gq
2 жыл бұрын
what is the range of frequencies used for the FFT ?
@overcomplete
4 жыл бұрын
might be a bit advanced but the bit I'm interested in is zero-padding. thanks great vids as always
@martinignaciofeldman
Жыл бұрын
great video, thanks
@jumbyvt6839
2 жыл бұрын
This was really good. Great job.
@JohnWick-xd5zu
4 жыл бұрын
Thank you sir
@complex_variation
4 жыл бұрын
wow steve all your videos are way too great I'm buying your book as soon as I can.
@davidajaba
4 жыл бұрын
I'm here first... Awesome video... 😁
@TheGhostcowvaca
Жыл бұрын
Very clear and easy to understand!
@sirajtayyabkhan6820
3 жыл бұрын
Brilliant video, very concise, and clear.
@delendaanouar7180
4 жыл бұрын
Hi, Great video as usual. Lately I have heard of Haline which is used in image processing and it is 100 times faster than Matlab, I wonder if Haline using another algorithm differs from that of FFT, and another question is how we can return the signal word to the image(image=signal!!)?
@mohamedking96
2 жыл бұрын
an image is simply a set of points(x,y) which they could be plotted like a signal
@erick_ac
Жыл бұрын
the fast fourier transform is a discrete transform meaning that the values it receives are in a discrete domain, it's not a continuous signal. it's extensively used in computing because of the discrete nature of digital stuff like audio and video
@jms547
4 жыл бұрын
So after thresholding do the large-amplitude components tend to sit on a compactly supported set as you kind of suggest in your sketches, or are they scattered all over Fourier space? Thanks for the great lectures!
@Miyelsh
4 жыл бұрын
They would be pretty heavily localized, but depend a lot from image to image. A picture of a white square on a black background would look kind of like a puddle after a rock was dropped in, with circles emmanating from the center.
@jms547
4 жыл бұрын
@@Miyelsh thanks!
@erick_ac
Жыл бұрын
you could design an image to scatter over the fourier space, but regardless, the inverse operation to form the image only keeps the coefficients needed for the higher values, aka, you store their coordinates from the fourier space although one could totally design a way to store the coefficients that best fit the described set in the sketch, but you would need to study a very particular use case to apply it (like maybe how the fourier space looks on cartoony images or just compressing for text)
@igorg4129
4 жыл бұрын
Great. Thank you very much sir. Question. In the middle of fft2 image There are low frequensy sinewaves, or there are high amplitude sinewaves?
@Miyelsh
4 жыл бұрын
The middle is low frequency waves. The very center is what's called the DC term, which is the overall average brightness of the image. The edges would be terms that are alternating every pixel, so you would only see those if you did something like took a picture of a screen door.
@arvindp551
3 жыл бұрын
It's 2 AM in New Delhi and you have made my day. Thank you Steve!
@yuurishibuya4797
3 жыл бұрын
Get a life!
@arvindp551
3 жыл бұрын
@@yuurishibuya4797 well, I have everything i need, you name it...except a job in engineering field for which I had left my previous stable-cum-peaceful job.
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