How Convolutional Neural Networks work

Part of the End-to-End Machine Learning School Course 193, How Neural Networks Work at e2eml.school/193
A gentle guided tour of Convolutional Neural Networks. Come lift the curtain and see how the magic is done. For slides and text, check out the accompanying blog post: brohrer.github.io/how_convolut...
Check out • How Convolutional Neur... for better audio and a more detailed account.
Follow me for announcements: / _brohrer_

[@IsaacsMusic]

i've watched a good dozen of videos about convolutional neural networks but you've nailed it!!! thx for the insights

[@BrandonRohrer]

Thanks Ivan :) I'm very happy to hear it.

[@minhuang8848]

Really nice presentation for sure. Just one recommendation: please normalize your audio. It's super easy to do and makes people feel much more comfortable as they don't have to crank up the volume where any tiny notification will blow your eardrums to bits. I also feel like you could easily talk way faster, although adjusting playback speed manually does the trick just fine.

[@BrandonRohrer]

Thanks Min, and I appreciate the feedback. I've actually been speeding up my delivery just a bit in subsequent presentations. I was trying to keep the pace moderate for non-native English speakers, but went overboard. I like the audio normalization tip. I'll make sure to do that next time.

[@cheater00]

please re-upload this one with the audio made louder. btw, normalizing might not make it loud enough, feel free to make it louder by hand - the peaks will just be cut off, the speech will still sound good most likely. for best results use an audio dynamics compressor.

[@AznofHK]

pace is no big deal, and it might even be better to err on the slow side. people who want it faster can watch at 1.25X or 1.5X speed, but 0.5x speed gets a little bit wonky. gotta love youtube.

[@Tasaq313]

Finally, someone who explained it in details, not some bunch of "CNN takes image, makes some stuff and poof it can classify" crap. Thank you, you are the hero wee need, not the hero we deserve.

[@BrandonRohrer]

Thanks Adam! Yours is officially the best compliment ever, narrowly beating out "The Mr. Rogers of Data Science." img0.etsystatic.com/065/1/9143987/il_570xN.761988760_8vsd.jpg

[@Tasaq313]

While my comment got your attention I will slip in an extra question for you, it's very clear for me how CNN can classify, but what about image processing? Can it do that (on it's own)? For example like noise removal or image colorization. It's like we would need to skip pooling, but then wouldn't we lose global information that we would need?

[@learningyt4725]

Yes. CNN explained in details, step by step. I appreciate it very much!

[@Cyranek]

I have a report on neural networks due 3 days into the semester so this helps and makes me not want to die as much as before.

[@SV-xt2bu]

what are you studying?

[@katkosmos]

Damn, dude. Didn't expect to see you here!

[@chucky2578]

What was your report on? Melon classification using NN?

[@MinerMovie]

Cyranek meme god

[@iuliancernat8944]

Made my end project in 3 days

[@sau002]

The example with X and O was a brilliant approach. This is where most machine learning videos miss out.

[@maximthemagnificent]

Don't be scared off by the length of this video. Excellent use of simple examples to illustrate core concepts. The author has a finely tuned sense of what to focus on and what to gloss over to impart the gist. Many explanations either get lost in (easily forgotten) jargon or muddied by too many details too fast. The overview of the limitations and application rules of thumb is especially valuable. Great stuff.

[@courageouscuber9278]

It honestly isn't lengthy for the content that is inside! People can search for years and struggle to find something that they can understand on this topics, and when they do, it takes a very long time to learn. This is only half an hour, shorter than a class that you would take at a university, but it is so worth it!

[@sanketshah3568]

I don't know why but I teared up after understanding something so clearly. Like just how beautiful the intuition is, and I feel blessed to have something so amazing as my career, while half of the world is stuck in dull jobs they hate. You are a hero.

[@BrandonRohrer]

Sanket Shah, your comment made me tear up too. I'm very happy the video helped.

[@thomasto314]

Hands down one of the greatest educators of the 21st century.

[@OlivierSimpleLife]

the most comprehensive guided tour ever done about convolutional Neural Networks, and within less than 30min. Simply brilliant !

[@BrandonRohrer]

Thanks olivier! It's also a huge honor to get a nod of approval from Ted.

[@revoiceful]

I'm a second year engineer from Germany and currently reading "Python Machine Learning" from Sebstian Raschka (newbie to programming as well!). Your videos clearly put all the pieces together. Thank you for being a great teacher :)

[@askmiller]

So for a while I had a basic understanding of this algorithm, but I would never have felt comfortable trying to make one on my own. Watching this video felt like all of the pieces were lining up together into a beautiful picture of how this algorithm works. This was really well done.

[@BrandonRohrer]

Thanks +askmiller. You made my day.

[@pedromv]

​@@BrandonRohrer I'm trying to implement my own algorithm as well and I coudn't understand how would I make the algorithm decide which features are relevant. In your explanation, it seams to me that you choose them and not the algorithm itself

[@rickbarrington]

I had bookmarked this post, came back after 2 years and found I understand it so much better. Wish I could give it a second thumbs up. Thanks!

[@BrandonRohrer]

I'm glad to hear it :) Welcome back.

[@ccusonline]

Brandon, Man, I have watched numerous videos but nobody explains it as cleary as you do. I beleive any in the IT world, watching your video will understand. Good job making it dumbproof and so within reach.

[@iLLt0m]

Best visualization of convolution I've seen.

[@harvinderdabasutube]

Best video till now ... which I saw for CNN ... Great..

[@reb5642]

Sir, many people has already said that your video is the best, like many other videos about CNN get the same comments. But with me, i think your video is the best. Your voice, your slide, the video length,... is perfect. Thanks you so much sir.

[@Hoop0u]

I'm non english speaker and I watched a bunch of videos on Neural Network but your video is by far the best one. I think I've manage to learn the weight thing. Thanks a lot.

[@kiranmarri7384]

A saying "Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality" by Tesla.... it is really true in the case of CNN concepts. Brandon.. you have structured the concepts of CNN so simple and easy to understand in this tutorial. Best video on CNN so far. Looking fwd for more video sessions from you !!!

[@BrandonRohrer]

Thanks for the wisdom Kiran. Tesla is a hero of mine.

[@70ME3E]

actually it has a "relation to reality" as it implements our object classification in our brain. the convolutions' output "feature maps" are bigger and bigger features - like lines, curves, then bigger and bigger parts of the object - we recognize and that's how we classify the objects too. pooling helps us recognize them invariant of angular etc. differences, like if I hold up a shoe for you sideways, you'll still know it's a shoe

[@youssefmimouni3700]

You make complicated things look quite easy to understand

[@BrandonRohrer]

I appreciate it Youssef

[@sadhguruDailyShorts]

Thats really true

[@HAmesa-KAmyster-soul]

i've spent hours and hours trying to figure out what CNNs are , but these 30 minutes is the one that fixed my issue , thanks a lot Sir !

[@jagan1957]

Every slide that is presented here opens up a new dimension of understanding about the CNNs. Awesome job!!!

[@sahildadia590]

The best and the most detailed explanation I have ever heard. good to know you didn't rush, through the convolution, pooling or anything else! The example was great and easy to understand. Thumbs up!!!!

[@BrandonRohrer]

I'm happy it was clear Sahil. That is my number one goal.

[@prakharmishra8194]

By far, the best explanation over the web.

[@GabeGibitz]

This was better than any Stanford or Harvard lecture on this topic. Well done! Thank you!

[@BrandonRohrer]

Wow, thanks Gabe! I'm glowing.

[@mff5610]

This Guy Deserves a Noble Prize for Teaching!

[@akhileshpandey123]

Please make more videos like this. You helped me understand concept which I was learning for months in just 26 min.... Thanks Sir..

[@khoiphan292]

Great content! Amazing visualization for all the maths! I finally understood what Convolutional Neural Networks are all about. Even after a whole course on ML at uni, I still couldn't get it, but a mere 26 minutes of your video did the wonder. Keep it up! :)

[@behezinampalanga887]

One of the best videos out on the subject. The author is able to incrementally stack the concepts in an easy way to follow, introducing the complexity of the concepts in a timely and organized way that allow the viewer to follow and grow in understanding. Most of them out there jump to quickly to the math behind it where at the end you miss the point and don't know why all those complex steps. Thanks Brandon Rohrer for the this approach to explain this.

[@BrandonRohrer]

Thanks Behezinam! I am very happy to hear it :)

[@EthanWangAertoria]

Your video is the best illustration of CNN I found so far

[@TheTilgath]

Seriously my graduate level class on Image Processing has spent two lectures explaining this and only now it finally clicks!

[@BrandonRohrer]

I'm glad to hear it Joel! Hang in there.

[@shahabazboss2]

Best explanation for Convolutional Neural Networks ever seen

[@peterklemenc6194]

Haven't even finished watching this, just to comment. It's BRILLIANT! Very well explained. Thank you

[@guiray2000]

I am new to neural networks and found this one of the clearest tutorials ever. Very good.

[@31337flamer]

ty .. this answers some of my questions about cnns regarding pattern recognition (the filtering steps)..

[@pashuu007]

Best Video I ever seen about neural network....thanks for uploading Brandon

[@amardhillon314]

This is the simplest video i 've seen on CNN, by simplest I mean explaining all the concepts in a simpler manner. Thaks a ton .

[@nandu001]

This is the best that I heard on convolutional NN. It is easy to describe difficult things in difficult ways. Much harder to do the same in simple words. You have nailed it.

[@TidalMaker]

1) You're cute 2) The graphics are great 3) The video was very informative 4) The sound had a bit of echo

[@adamboris7925]

Tres Kewlshoes first part is disrespectful and inappropriate.

[@randiaz95]

​@@adamboris7925 How so? I wish people would say I am cute. Don't you? Plus I don't think Tres is looking for a partner over youtube lol. I think it was meant more for comedic relief after watching a 30 minute video on machine learning.

[@ChessCat1500]

Randy Diaz cute sounds gay

[@rohanagrawal6870]

@@ChessCat1500 you're gay to find it gay

[@evasionlan]

very good video, finally someone explained it clearly. Thank you !

[@BrandonRohrer]

Thank you Wang :) I'm happy it was clear.

[@xavierprudent6963]

I would say the clearest introduction to the subject I have ever watched, thank you.

[@ChicagoBob123]

Talk about straight forward. Yes! I have been struggling with all the terminology and basic language in this science to find out that its not that hard to understand at all. THANK YOU.

[@BeDirector]

beatifull video man, i see you spend a lot of time making it. I enjoyed it very much, thank you :D

[@playlistsirois]

This video saved my semester.

[@yimzom8193]

What are you studying?

[@antoniokishore]

Very useful and clear presentation

[@VoidSpaceGirl]

same

[@asafr2229]

You took a subject many others struggle to explain (also here in youtube) and what you made is art.. the are of simplification. Many thanks buddy!

[@MdNasirUddinLaskarBD]

Clear description of what's happening behind the scene. Thanks for the great tutorial!

[@juancuadra3697]

Brandon, this is really good. Thank you very much!

[@anobjectiveninja]

Great introduction to ConvNets! Thanks a lot. Please also make similar videos about RNN, LSTM, etc.

[@jaheduddin1409]

Also please if possible do a series on Gradient descent algo's such as momentum, AdaGrad, Adam etc. with mathematics

[@Ken-S]

+1

[@Basicguy1798]

You sir, are the best minimalist teacher I have found on the internet. For a beginner you are a blessing!!

[@juncaoazgmail]

This is the cleanest explanation of CNN I have never watched on KZbin! Thanks for sharing!

[@kautsarfadlyfirdaus1879]

beautiful explanation! 10/10

[@BrandonRohrer]

Well thank you very much!

[@tamilupk]

You nailed it, best video in CNN so far, at lest for a ML newbie like me.

[@ligialikesapples]

Thank you so much for this video, I have an exam in a couple of days and I have been so lost with all these terms but your video is so incredibly clear. More than the recorded lectures of my professor and books I have read. Thank you for taking the time to explain in a way that makes someone with very little knowledge on the topic feel like an expert!

[@NikRoby]

This is the best and most clear explanation of back propagation and how neural networks works. Thank you for such excellent work.

[@saradjaroud971]

When you used the filter/kernel, why did you average the results?? Everywhere else I've looked there's only the sum

[@windar2390]

this is the best presentation of cnns i've seen so far. good job. since it was so good, i wish you explained backpropagation a little bit more because this is something i still dont know how it works in detail. there can be so many layers and weights, how you know which one you have to adjust?

[@vitorpy]

I was thinking the same. How backpropagation, or any other learning algo, works with this?

[@BrandonRohrer]

Thanks Windar, I'm glad it was helpful! And thanks for the +1 on backpropagation. I've added "How Backprop Works" to my to-do list. The really short version is that every weight in every layer gets adjusted a little bit every time. The slightly longer version is that it helps if you randomly select half the weights in every layer to adjust and pick a new set each time. This is called "dropout" and it helps avoid overfitting.

[@windar2390]

wow, even in 1-2 phrases you can explain more than other guys in 1 hour presentations. "How Backprop Works" from you would be nice, but dont do it just because of me. i subscribed anyway!

[@TonyDiCroce]

You compute the derivative of each unit from back to front. The derivative is really a slope. The slope then tells you what direction (+ or -) you should adjust the weight in order to improve the output of this particular unit. Do this across the whole network and you've improved the output of the whole network. Check out karpathy's blog: karpathy.github.io/neuralnets/

[@SaeedRanjbar]

I watched series of videos and I was trying to find one that covers the core concepts without going into details and I could not. Finally, I came up with this video. I am sure you knew what other videos are missing and you have covered all here ! Good job

[@JuanuHaedo]

I agree with most people. The explanation about Convolutional Neural Networks made me finally understand how they work! Thanks!

[@changyongkang7651]

I appreciate, professor^^ from S.korea

[@korean4130]

chang yong kang 여기서 뵙네요...하핳😄

[@changyongkang7651]

@@korean4130 님 저도 치과 진단에 도움이 될까 해서 관심을 ㅎㅎ^^ m.blog.naver.com/nkabcd2/221637820902

[@nedomenya739]

Can you create brain-computer interface?

[@austinbecton5341]

Hello from 청주시 haha

[@changyongkang7651]

@@austinbecton5341 ^^ welcome ^^ have a good day ^^

[@codedragon6237]

It's inaudible :(

[@dzsukov]

These 26 minute video clarified a concept that days of research elsewhere hasn't been able to so concisely and intuitively, so it helps me understand rather than just be able to "replicate" a model. Thanks Brandon, this was brilliant!

[@abhijitb9618]

extremely helpful...most clear and crisp explanation i found so far on the working of the convolutional neural nets...thanks

[@BrandonRohrer]

Thanks! I'm really happy it worked for you Abhijit.

[@abdelrahmangamalmahdy]

The volume is too low, I can't even hear you!

[@CandidDate]

When I'm looking at pornography, my brain votes 1.00 that this is pornography. ;)

[@alisaghi051]

I mean knowing how to simplified the obvious things is an ART. Thanks for the video.

[@BrandonRohrer]

Many thanks, Ali.

[@riccardoandreetta9520]

definitely one of the most simple and useful videos, if you're trying to understand something about it

[@2pist]

I'm stoked. As I was listening I thought of the fix a little differently than pooling, but came to the same conclusion. We are dividing out then reexamine based on the resulting reduced pixels. It's a computers way of stepping back, not looking at individual pixels allowing only the groups of pixels to create the shape. It's like getting a computer to generalize instead of being specific.

[@davidguaita]

There are many explanations about ConvNets around, but they always seem to miss the point that the filters are also learned. Congrats for your detailed and kind tutorials. Thank you.

[@tubeyoukonto]

You are a lifesaver!!! I have to elaborate a paper on CNNs for uni (ImageNet Classification with Deep Convolutional Neural Networks) and it really got me confused with all those new terms and general complex language (engl. is not my first language). Thise video helped me even more than I hoped! Thank you!!

[@cryptonetcentralusa5592]

By far the best explanation I got watching your video about CNN ... your clear, concise and easy to understand style of teaching makes even a convoluted concept like CNN so easy to grasp the very first time. Thank you very much!

[@mohamedhammoud3010]

Clear, concise, and very well organized. Props.

[@DaveVoyles]

This was --hands down-- the best intro video on the topic I have seen yet. Great work. Was a fan of your videos at Microsoft

[@srivastavaprakharsunil9732]

your way of explaining things using live examles is amazing, thanks for the video

[@BrandonRohrer]

Thank you Srivastava :)

[@me-zb7qm]

You explained this better than any of my professors. Instant subscribe!

[@wlancer8826]

THE BEST introduction to convolutional neural networks for BEGINNERS!!! Many many thanks!

[@rohansathasivam7407]

With just first 9 minutes of video, I was so sure I will understand the rest of the video. Thank you!

[@AnuliaSuper]

This is seriously the best video on CNNs!!! I cannot believe the skills you have to make this soo easy to understand!! Thank you so much, everything is so clear to me now : )

[@AhmedKachkach]

Fantastic explanation. There were some things that weren't clear enough for me (how the convolutional filters were learned via backpropagation) but you explained everything so clearly that this is even usable by people with no prior ML or ANN background. Thanks for posting this, Brandon!

[@BrandonRohrer]

Thanks Ahmed! That's exactly what I was aiming for. I'm glad it helped.

[@CarasGaladhon]

Thanks so much for this excellent explanation. I sometimes just can't understand something at all without seeing it graphically. This helped.

[@therimshak]

EXCELLENT explanation without maths of the how. Great job.

[@vidhi1257]

I am glad that I understood CNN finally with the help of this video, You are exceptionally great tutor. Thank you so much.

[@priyankajadhav9373]

The flow of your explanation was neat and point to point thanks a ton!

[@vinayakparab6260]

Thank you so much for explaining neural networks in such a easy way. I was really confused when I saw the other videos and people mentioning about gradient descent and back propagation.But the concepts are now clear. Thanks again for this awesome video.

[@FelipeSouza-ui9rd]

Awesome video on convolution neural networks. Thanks so much Brandon, I was having difficulty to understand the layers but you made it crystal clear.

[@pfeilbr]

Best video I've found on CNNs. Thanks for taking the time to make this topic more accessible!

[@vilasiniraja2290]

Beautifully explained, with the perfect flow right from the beginning !!!

[@MultiJoniboy]

Best video about CNNs i've seen so far. I am new to coding (been doing it for 6 months) but i still understood how it works, and how it might look when written down in my code editor. Awesome job! Thanks a lot!

[@BrandonRohrer]

Thank you Jonas! I'm really happy it has been helpful.

[@Relative0]

Astronomical explanation of several concepts and how they work together! Wow!

[@robkaq2]

This is the best tutorial in this topic i've seen so far. Thanks for sharing!

[@andikawilliam2053]

Great video. I feel like this is one of the most comprehensive especially on how it explains the process step by step (for instance i noticed other explanations don't bother with how stacking layers works)

[@jjosyde]

26+ min video but so dense with information, well done sir!

[@jinyangdeng875]

Concise and understandable explanation, with great rule of thumb at the back. Awesome video!

[@-beee-]

This is the first time I've really felt like I "got" what was going on and why so many talks emphasize image analysis. Thank you for tying it back to language and sound as well.

[@BrandonRohrer]

That's wonderful Bellabellie! I'm pleased to hear it.

[@anandrhuilgol]

This one video clarified huge number of questions on my mind. Very Very helpful. In fact a 'must watch' for all beginners.

[@user-mj1qw8ef2i]

I like it. Being not too complicated with nitty-gritty details, and not overly simple either, this video is very good for gaining basic understanding of CNNs.

[@AllBecomesGood]

One of the better videos explaining Convolutional Neural Networks! Thanks!

[@iphykelvin8698]

Watching this video made the whole concept much easier to understand..great video. Thanks man.

[@GloryBharat]

Awesome presentation-beautifully demystified the complex subject

[@janmichaelbesinga3867]

Very good for startups and very straight forward. This one deserves my like! Regards from the Philippines.

[@yf1177]

Fantastic presentation! You provided exactly the information I was looking for along with exceptionally clear explanations. Thank you!!

[@jacksonmeeks9313]

This is one of the best explained videos I've ever watched. Subscribed.