Image Recognition – AI in Media and Society

What is a stop sign? What is a person?

April 16, 2023 Mindy McAdams

I was reading an article in Scientific American, found by one of my students, and I came across this passage:

“A Tesla on autopilot recently drove directly toward a human worker carrying a stop sign in the middle of the road, slowing down only when the human driver intervened. The system could recognize humans on their own (which is how they appeared in the training data) and stop signs in their usual locations (as they appeared in the training images) but failed to slow down when confronted by the unfamiliar combination of the two, which put the stop sign in a new and unusual position.”
—Artificial General Intelligence Is Not as Imminent as You Might Think, July 1, 2022 (boldface mine)

The article helpfully linked to a YouTube video, in which we see and hear the situation. The driver is narrating as the car makes its decisions: “All right, we’re having to take over. It’s not slowing early enough. [Pause.] Yep, the car keeps trying to go each time … That’s really unfortunate. It sees the person, it sees the stop sign, but it’s almost not taking it seriously.”

View through a car's windshield shows a person holding a stop sign, standing in the middle of a road — *Capture from the YouTube video at 03:14*

This is not a big surprise if you understand the nature of training data and the long tail — a person walking across a street is common enough, and a stop sign is very common, but a person holding a stop sign and standing (not walking) in the middle of the lane occurs much less frequently than the other two. It’s not rare, but it’s not something we encounter every day while driving.

Here’s the thing: Later in the article, the author says: “You can’t deal with a person carrying a stop sign if you don’t really understand what a stop sign even is.” And at first, I’m like: Cool, cool. That’s good, that’s a nice observation.

And then I thought: Wait a minute. Wait just a minute. Of course an AI system understands nothing, nothing at all. It has been trained to recognize a stop sign. It has been trained to recognize a human (especially a human in the road). But what is really happening in the video? The car is stopping, briefly, and then starting up again. It does this more than once. The driver has to intervene, put a foot on the brake, to stop the car from going forward and hitting the person. The car is behaving the way it was programmed to behave at a stop sign — and not the way it was programmed to behave if a human is walking in front of the car.

The central point here is not that the car’s system doesn’t know what a stop sign is (which, it’s true, it doesn’t). The central point is that given a human holding a stop sign, the system behavior governing a regular, side-of-the-road stop sign has dominated, has come to the fore as the default behavior — and the system behavior that prevents a human from being run over is not in play.

This is no trolley problem. The car’s AI did not decide to kill the human. It did not weigh the options. In an unlikely case (an edge case), it defaulted to the common, everyday case: There is a stop sign. This is what I do when there is a stop sign.

I’m blogging this because this is great discussion material for students and others!

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Pastries, cancer cells, and neural networks

May 10, 2021May 10, 2021 Mindy McAdams

The system described in this wonderful New Yorker article from March 2021 is NOT a neural network, and that’s one of the things that make it fascinating. I’ve written before about ImageNet and how neural networks, trained on humongous datasets of labeled digital images, are able to very accurately say what is in a photograph that the system has never “seen” before.

This is different.

This system, developed by a small company in Japan, does not require hundreds or thousands of images of each object it needs to identify precisely because it doesn’t use a neural network. The technologies it uses can be called good old-fashioned AI (GOFAI). Essentially it consists of a collection of manually constructed algorithms.

*Above: BakeryScan at work: Screen capture from video (2017)*

The system also “learns,” but not in the typical black-box sense of today’s machine learning systems. It is widely used in the checkout systems of Japanese bakeries, which offer a bewilderingly large assortment of pastries and small bread items, many of which look quite similar to one another. BakeryScan was released in 2013; it was 15 years in development.

More recently, the bakery system has been adapted to recognize specific types of cancer cells. The new system is able to “look at an entire microscope slide and identify the cells that might be cancerous” (source: The New Yorker article).

Rather than summarizing the article further, I’m just going to urge you to read it. It’s very much worth your time.

Image recognition in medicine: MS subtypes

April 13, 2021 Mindy McAdams

Machine learning systems for image recognition aren’t always perfect — and neither are AI systems marketed for medical use, whether they use image recognition or not. But here’s an example of image recognition used in a medical context where the system appears to have succeeded at something significant — and it’s something humans can’t do, or at least can’t do well.

“Researchers used the AI tool Subtype and Stage Inference (SuStaIn) to scan the MRI brain scans of 6,322 patients with MS, letting SuStaIn train itself unsupervised. The AI identified 3 previously unknown patterns …” (Pharmacy Times). The model was then tested on MRIs from “a separate independent cohort of 3,068 patients” and successfully identified the three new MS subtypes in them.

Subtype and Stage Inference (SuStaIn) was introduced in this 2018 paper. It is an “unsupervised machine-learning technique that identifies population subgroups with common patterns of disease progression” using MRI images. The original researchers were studying dementia.

Why does it matter? Identifying the subtype of the disease multiple sclerosis (MS) enables doctors to pursue different treatments for them, which might lead to better results for patients.

“While further clinical studies are needed, there was a clear difference, by subtype, in patients’ response to different treatments and in accumulation of disability over time. This is an important step towards predicting individual responses to therapies,” said Dr. Arman Eshaghi, the lead researcher (EurekAlert).

Sources: Artificial Intelligence Weekly newsletter, from The Wall Street Journal; Pharmacy Times; EurekAlert.

Can AI ‘see’ what you draw?

October 2, 2020October 1, 2020 Mindy McAdams

For Friday AI Fun, let’s look at an oldie but goodie: Google’s Quick, Draw!

You are given a word, such as whale, or bandage, and then you need to draw that in 20 seconds or less.

*Screenshot 1 from Google’s Quick, Draw!*

*Screenshot 2 from Google’s Quick, Draw!*

Thanks to this game, Google has labeled data for 50 million drawings made by humans. The drawings “taught” the system what people draw to represent those words. Now the system uses that “knowledge” to tell you what you are drawing — really fast! Often it identifies your subject before you finish.

It is possible to stump the system, even though you’re trying to draw what it asked for. My drawing of a sleeping bag is apparently an outlier. My drawings of the Mona Lisa and a rhinoceros were good enough — although I doubt any human would have named them as such!

*Screenshot 3 from Google’s Quick, Draw!*

Google’s AI thought my sleeping bag might be a shoe, or a steak, or a wine bottle.

*Screenshot 4 from Google’s Quick, Draw!*

The system has “learned” to identify only 345 specific things. These are called its categories.

You can look at the data the system has stored — for example, here are a lot of drawings of beard.

*Screenshot 5 from Google’s Quick, Draw!*

You can download the complete data (images, labels) from GitHub. You can also install a Python library to explore the data and retrieve random images from a given category.

What is a neural network and how does it work?

September 10, 2020June 3, 2021 Mindy McAdams

The most wonderful thing about YouTube is you can use it to learn just about anything.

One of the 10,000 annoying things about YouTube is finding a good, satisfying version of the lesson you want to learn can take hours of searching. This is especially true of videos about technical aspects of machine learning. Of course there are one- and two-hour recordings of course lectures by computer science professors. But I’ve been seeking out shorter videos with more animations and illustrations of concepts.

Understanding what a neural network is and how it processes data is necessary to demystifying machine learning. Data goes in, results come out — but in between is a “black box” consisting of code and hardware. It sort of works like a human brain, and yet, it really doesn’t.

So here at last is a painless, math-free video that walks us through a neural network. The particular example shown uses the MNIST dataset, which consists of 70,000 images of handwritten digits, 0–9. So the task being performed is the recognition of those digits. (This kind of system can be used to sort mail using postal codes, for example.)

What you’ll see is how the first layer (a vertical line of circles on the left side) represents the input. If each of the MNIST images is 28 pixels wide by 28 pixels high, then that first layer has to represent 784 pixels and each of their color values — which is a number. (One image is the input — only one at a time.)

The final vertical layer, all the way to right side, is the output of the neural network. In this example, the output tells us which digit was in the input — 0, 1, 2, etc. To see the value in this, go back to the mail-sorting idea. If a system can read postal codes, it recognizes several numbers and then transmits them to another system that “knows” which postal code goes to which geographical location. My letter gets sorted into the Florida bin and yours into the bin for your home.

In between the input and the output are the vertical “hidden” layers, and that’s where the real work gets done. In the video you’ll see that the number of circles — often called neurons, but they can also be called just units — in a hidden layer might well be less than the number of units in the input layer. The number of units in the output layer can also differ from the numbers in other layers.

When the video describes edge detection, you might recall an earlier post here.

Beautifully, during an animation, our teacher Grant Sanderson explains and shows that the weights exist not in or on the units (the “neurons”) but in fact in or on the connections between the units.

Okay, I lied a little. There is some math shown here. The weight assigned to the connection is multiplied by the value of the unit to the left. The results are all summed, for all left-side units, and that sum is assigned to the unit to the right (meaning the right side of that one connection).

The video bogs down just a bit between the Sigmoid squishification function and applying the bias, but all you really need to grasp is that the value of the right-side unit shows whether or not that little region of the image (in this case, it’s an image) has a significant difference. The math is there to determine if the color, the amount of color, is significant enough to count. And how much it should count.

I know — math, right?

But seriously, watch the video. It’s excellent.

“And that’s a lot to think about! With this hidden layer of 16 neurons, that’s a total of 784 times 16 weights, along with 16 biases. And all of that is just the connections from the first layer to the second.”
—Grant Sanderson, But what is a neural network? (video)

Sanderson doesn’t burden us with the details of the additional layers. Once you’ve seen the animations for that first step — from the input layer through the connections to the first hidden layer — you’ll have a real appreciation for what’s happening under the hood in a neural network.

In the final 6 minutes of this 19-minute video, you’ll also learn how the “learning” takes place in machine learning when a neural net is involved. All those weights and bias values? They are not determined by humans.

“Digging into what the weights and biases are doing is a good way to challenge your assumptions and really expose the full space of possible solutions.”
—Grant Sanderson, But what is a neural network? (video)

I confess it does get rather mathy at the end, but hang on through the parts that are beyond your personal math background and listen to what Sanderson is telling us. You can get a lot out of it even if the equation itself is like hieroglyphics to you.

The video content ends at 16:26, followed by the usual “subscribe to my channel” message. More info about Sanderson and his excellent videos is on his website, 3Blue1Brown.

Face detection without a deep neural network

August 25, 2020August 28, 2020 Mindy McAdams

I was surprised when I watched this video about how most face detection works. Granted, this is not face recognition (identifying the specific person). Face detection looks at an image or video and can almost instantly point out all the human faces. In a consumer camera, this is part of the code that puts a rectangle around each person’s face while you’re framing your shot.

What’s wonderful in the video is how the Viola–Jones object detection framework is illustrated and explained so that even we non-math types can understand it.

Like the game cases I wrote about yesterday, this is a case where tried-and-true algorithms are used, but deep neural networks are not.

As is typical with AI, there is a model. How does the code identify a human face? It “knows” some things about the shape and proportions of human faces. But it knows these attributes (features) not as noses and eyes and mouths — as we humans do. Instead, it knows them as rectangular shapes that map very well to the pixels in a digital image.

*Above: Graphic from Viola and Jones (2001) — PDF*

Make sure you stay with the video until 3:30, when Mike Pound begins to draw on paper. (This drawing-by-hand is a large part of why I love the videos from Computerphile!) At 8:30 he begins drawing a face to show how the algorithm analyzes that segment of an image.

The one part that might not be clear (depending on how much time you spend thinking about pixels in images) is that the numbers in the grid he draws represent values of lightness or darkness in the image. In all cases, computers require knowledge to be represented as numbers. When dealing with images, numbers represent differences. To compare sections of an image with other sections, the numeric values for one section are added up and compared with the sum of numeric values from another section.

The animations in the final three minutes of the video provide an awesomely clear explanation of how the regions of the image are assessed and quickly discarded as “not a face” or retained for further examination.

Computers are lightning-fast at these kinds of calculations. This method is so efficient, it runs rapidly even on simple hardware — which is why this method of face detection has been in use since 2002.

Visual Chatbot: What can AI tell you?

August 21, 2020September 18, 2020 Mindy McAdams

To see for yourself the product, or end results, of an AI system, check out the Visual Chatbot online. It’s free. It’s fun.

Screenshot of dialog with Visual Chatbot

This app invites you to upload any image of your choice. It then generates a caption for that image. As you see above, the caption is not always 100 percent accurate. Yes, there is a dog in the photo, but there is no statue. There is a live person, who happens to be a soldier and a woman.

You can then have a conversation about the photo with the chatbot. The chatbot’s answer to my first question, “What color is the dog?”, was spot-on. Further questions, however, reveal limits that persist in most of today’s image-recognition systems.

The chat is still pretty awesome, though.

Public domain photo of a soldier and a dog indoors, probably in an airport, with a "Welcome Home" balloon. U.S. Department of Defense photo. — *U.S. Department of Defense photo, 2015 (public domain)*

The image appears in chapter 4 of in Artificial Intelligence: A Guide for Thinking Humans, where author Melanie Mitchell uses it to discuss the complexity that we humans can perceive instantly in an image, but which machines are still incapable of “seeing.”

In spite of the mistakes the chatbot makes in its answers to questions about this image, it serves as a nice demonstration of how today’s chatbots do not need to follow a set script. Earlier chatbots were programmed with rules that stepped through a tree or flowchart of choices — if the human’s question contains x, then reply with y.

You can see more info about Visual Dialog if you’re curious about what the Visual Chatbot entails in terms of data, model, and/or code.

Below you can see some more questions I asked, with the answers from Visual Chatbot.

Some of my favorite wrong answers are on the last two screens. Note, you can ask questions that are not answered with only yes or no.

ImageNet and labels for data

August 19, 2020September 3, 2020 Mindy McAdams

Supervised learning is a type of machine learning in which a model is trained using labeled data. You begin with a very large collection of labeled data. (In the case of ImageNet, the data were all digital images. For the Iris Data Set, the data all refer to individual iris flowers, which can be divided into three related species. For the MNIST dataset, the data are images of about 70,000 handwritten numbers, 0 through 9.)

You divide the dataset into two parts, the training data and the test data. The split might be 70/30, or 80/20. You don’t choose which data goes into which group. Then you run the training data many, many, many times, adjusting certain parameters in the code along the way, until the code consistently returns good results — that is, the thing the code identifies (an object in an image, an iris species, a number) matches the label (which is hidden from the code).

At that point, you have a trained model. You feed the test data set to it and see whether the accuracy rate is also high. (It’s important that none of the test data were used to train the model.) Again, the proof is in the labels.

In a later post I will discuss how data come to be labeled. (Hint: It’s not elves.) In this post, I will discuss bad labels. Specifically, I want to highlight the work that AI researcher Kate Crawford and artist-researcher Trevor Paglen did around the famous ImageNet dataset.

In the video above, Crawford and Paglen present this work and show a lot of great examples. They also published a long article about the work, if you’d rather read than watch.

ImageNet is a huge collection of labeled images. More than 14 million images. They were labeled according to a set of categories and synonym groupings from WordNet, an English-language lexical database. The images were labeled by humans.

And that, it seems, is at the root of the problem.

Crawford and Paglen were interested in the ImageNet photos of people. Person is a category in WordNet. Within the category, there are many descriptive terms for people, such as “cheerleaders, scuba divers, welders, Boy Scouts, fire walkers, and flower girls.” So the photos of people in ImageNet are labeled with these terms. However, not all terms are neutral.

“A young man drinking beer is categorized as an ‘alcoholic, alky, dipsomaniac, boozer, lush, soaker, souse.’ A child wearing sunglasses is classified as a ‘failure, loser, non-starter, unsuccessful person.’”
—Crawford and Paglen

You might say, well, where’s the harm? They are only labels in a database, after all.

The ImageNet database has been used to train many convolutional neural networks used in image-recognition software.

When you feed a photo of yourself into an image-recognition application, you might be surprised at the labels that are applied to you. For example, an image of Paglen (a white man with a shaved head) was labeled as “Klansman, Ku Kluxer.”

Paglen built a web app called ImageNet Roulette so that anyone could upload a photo of themselves or a friend and see what labels were applied. (The app is no longer online.) It became clear that perfectly innocuous people in photos were being labeled as criminals or dangerous, or with racist or sexist terms.

About 952,000 of ImageNet’s 14 million images were in the person category as of 2010 (source). Many of those images — with their labels — were removed after the opening of Crawford and Paglen’s art exhibition, Training Humans, in Milan in September 2019.

ImageNet has been used to train countless image-recognition systems since 2010.

Additional information:

Leading online database to remove 600,000 images after art project reveals its racist bias (September 2019), The Art Newspaper.

Racial and gender bias in AI

August 13, 2020August 24, 2020 Mindy McAdams

Different AI systems do different things when they attempt to identify humans. Everyone has heard about face recognition (a k a facial recognition), which you might expect would return a name and other personal data about a person whose face is “seen” with a camera.

No, not always.

A system that analyzes human faces might simply try to return information about the person that you or I would tag in our minds when we see a stranger. The person’s gender, for example. That’s relatively easy to do most of the time for most humans — but it turns out to be tricky for machines.

Machines often get it wrong when trying to identify the gender of a trans person. But machines also misidentify the gender of people of color. In particular, they have a big problem recognizing Black women as women.

A short and good article about this ran in Time magazine in 2019, and the accompanying video is well worth watching. It shows various face recognition software systems at work.

Another serious problem concerns differentiating among people of Asian descent. When apartment buildings and other housing developments have installed face recognition as a security system — to open for residents and stay locked for others — the Asian residents can find themselves locked out of their own home. The doors can also open for Asian people who don’t live there.

You can find a lot of articles about this widespread and very serious problem with AI technology, including the deservedly famous mug shots test by the American Civil Liberties Union.

“While it is usually incorrect to make statements across algorithms, we found empirical evidence for the existence of demographic differentials in the majority of the face recognition algorithms we studied.”
—Patrick Grother, NIST computer scientist

So how does this happen? How do companies with almost infinite resources deploy products that are so seriously — and even dangerously — flawed?

Yesterday I wrote a little about training data for object-detection AI. To identify any image, or any part of an image, an AI system is usually trained on an immense set of images. If you want to identify human faces, you feed the system hundreds of thousands, or even millions, of pictures of human faces. If you’re using supervised learning to train the system, the images are labeled: Man, woman. Black, white. Old, young. Convicted criminal. Sex offender. Psychopath.

Who is in the images? How are those images labeled?

This is part of how the whole thing goes sideways. There’s more to it, though. Before a system is marketed, or released to the public, its developers are going to test it. They’re going to test the hell out of it. This can be compared with when an AI is developed that plays a particular game, like Go, or chess. After the system has been trained, you test it. To test the system, you’re going to have it play, and see if it can win — consistently. So when developers create a face recognition system, and they’ve tested it extensively, and they say, great, now it’s ready for the public, it’s ready for commercial use — ask yourself how they missed these glaring flaws.

Ask yourself how they missed the fact that the system can’t differentiate between various Asian faces.

Ask yourself how they missed the fact that the system identifies Black women as men.

Fortunately, in just the past year these flaws have received so much attention that a number of large firms (Amazon, IBM, Microsoft) have pulled back on commercial deployments of face recognition technologies. Whether they will be able to build more trustworthy systems remains to be seen.

More about bias in face recognition systems:

Meet the computer scientist and activist who got Big Tech to stand down (Fast Company, August 2020) — about AI researcher Joy Buolamwini
NIST Study Evaluates Effects of Race, Age, Sex on Face Recognition Software (December 2019) — this article is the source for the pullout quote above
Timnit Gebru: Machine learning, bias, and product design (March 2018) — although this interview is older, I like how Gebru speaks about design: “We need more people who think about design working in AI, because oftentimes what’s happening is little things. … think about Siri or Alexa or these personal assistants who are women — what does that do to society, just portraying that stereotype?”
Meet the Googlers working to ensure tech is for everyone (May 2020) — Gebru is now an engineer at Google. Along with colleagues Tiffany Deng and Tulsee Doshi, she works on ensuring fairness in AI.

Ask a computer to draw what it sees

August 12, 2020August 24, 2020 Mindy McAdams

If a computer can correctly identify an object (an apple, a tricycle) or an animal such as a zebra, can it produce a drawing of that object or animal? This is something most people can do, even if their drawing skills are minimal. After all, almost anyone can play Pictionary.

This 8-minute video shows us what happened when a programmer-artist reversed the process of an AI that recognizes objects and animals in digital images. I really admire the deft storytelling here.

Object recognition has improved amazingly in the past 10 years, but that does not mean these AI systems see the same way as a human does. In some cases, that might not matter at all. In other cases, it can mean the difference between life and death.

In yesterday’s post I mentioned the way a convolutional neural network (part of a machine learning system) processes an image through many stacked layers of detection units (sometimes called neurons), identifying edges and shapes that eventually lead to a conclusion that the image is likely to contain such-and-such an object, animal, or person. Today’s video shows a bit more about the training process that an AI goes through before it can perform these identifications.

Training is necessary in the type of machine learning called supervised learning. The training data (in this case, digital images of objects and animals) must be labeled in advance. That is, the system receives thousands of images labeled “tiger” before it is able to recognize a tiger in a random photo or video. If a system can identify 20 different animals, that system was trained on thousands of images of each animal.

If the system was never trained on tigers, it cannot recognize a tiger.

So today’s video gives us a nice glimpse into how and why that training works, and what its limitations are. What’s really fascinating to me, though, are the images produced by programmer-artist Tom White‘s system.

“I have created a drawing system that allows neural networks to produce abstract ink prints that reveal their visual concepts. Surprisingly, these prints are recognized not only by the neural networks that created them, but also universally across most AI systems which have been trained to recognize the same objects.”
—Tom White

In the video, you’ll see that humans cannot recognize what the AI drew. The rendering is too abstract, too unlike what we see and what we would draw ourselves. Note what White says, though, about other AI systems: they can recognize the object in these AI-produced drawings.

This is, I think, related to what is called adversarial AI, which I’ll discuss in a future post.