Machine Learning Tutorial - Introduction to IMAGE RECOGNITION

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TRANSCRIPT

What is up, guys? Welcome to the first tutorial in our image recognition course. This is also the very first topic, and is just going to provide a general intro into image recognition. Now we're going to cover two topics specifically here. One will be, what is image recognition? And the other will be what tools can help us to solve image recognition? The first part, which will be this video, will be all about introducing the problem of image recognition, talk about how we solve the problem of image recognition in our day-to-day lives, and then we'll go onto explore this from a machine's point of view. After that, we'll talk about the tools specifically that machines use to help with image recognition. Specifically, we'll be looking at convolutional neural networks, but a bit more on that later. Let's get started with what is image recognition? Image recognition is seeing an object or an image of that object and knowing exactly what it is. At the very least, even if we don't know exactly what it is, we should have a general sense for what it is based on similar items that we've seen. Essentially, we class everything that we see into certain categories based on a set of attributes. That's why image recognition is often called image classification, because it's essentially grouping everything that we see into some sort of a category. Now the attributes that we use to classify images is entirely up to us. For example, if we're looking at different animals, we might use a different set of attributes versus if we're looking at buildings or let's say cars, for example. If we're looking at vehicles, we might be taking a look at the shape of the vehicle, the number of windows, the number of wheels, et cetera. If we're looking at animals, we might take into consideration the fur or the skin type, the number of legs, the general head structure, and stuff like that. It's entirely up to us which attributes we choose to classify items. And this could be real-world items as well, not necessarily just images. Now, this allows us to categorize something that we haven't even seen before. In fact, this is very powerful. We can take a look at something that we've literally never seen in our lives, and accurately place it in some sort of a category. We can often see this with animals. I highly doubt that everyone has seen every single type of animal there is to see out there. No doubt there are some animals that you've never seen before in your lives. But, you should, by looking at it, be able to place it into some sort of category. You should know that it's an animal. You should have a general sense for whether it's a carnivore, omnivore, herbivore, and so on and so forth. Now, another example of this is models of cars. Now, every single year, there are brand-new models of cars coming out, some which we've never seen before. Some look so different from what we've seen before, but we recognize that they are all cars. We can take a look again at the wheels of the car, the hood, the windshield, the number of seats, et cetera, and just get a general sense that we are looking at some sort of a vehicle, even if it's not like a sedan, or a truck, or something like that. Now, how does this work for us? Well, a lot of the time, image recognition actually happens subconsciously. In fact, we rarely think about how we know what something is just by looking at it. We just kinda take a look at it, and we know instantly kind of what it is. And a big part of this is the fact that we don't necessarily acknowledge everything that is around us. If we do need to notice something, then we can usually pick it out and define and describe it. Take, for example, if you're walking down the street, especially if you're walking a route that you've walked many times. It's highly likely that you don't pay attention to everything around you. Maybe there's stores on either side of you, and you might not even really think about what the stores look like, or what's in those stores. However, when you go to cross the street, you become acutely aware of the other people around you, of the cars around you, because those are things that you need to notice. In fact, even if it's a street that we've never seen before, with cars and people that we've never seen before, we should have a general sense for what to do. The light turns green, we go, if there's a car driving in front of us, probably shouldn't walk into it, and so on and so forth. Now, this kind of process of knowing what something is is typically based on previous experiences.