Do you remember these plots in the movie? In "Transformers 2", when the young actor and his friends passed the checkpoint, they were deceived by the military on duty, but they were discovered by the military's face recognition technology. In the 2014 remake of the "Mechanical Men", the mechanical warfare was first publicly exposed to the public, and all the faces were constantly scanned in the crowd, and the acquired faces were compared in the wanted criminal database. Yes, it was discovered in an instant that there was a wanted man who had escaped for many years and subdued it. There are many other movies, but all the secret departments of the United States will scan a variety of biometric features, from the fingerprints and irises of the early movies to the current faces.
What is face recognition?
Face recognition is a subdivision problem of visual pattern recognition, and it is probably the most difficult problem to solve. In fact, we are doing visual pattern recognition all the time, we obtain visual information through the eyes, and this information is recognized as a meaningful concept through the processing of the brain. So we know that there is a cup, a book, or something else in front of us.
We also do face recognition all the time. We encounter countless people in our daily lives, recognize those acquaintances, greet them, deal with them, and ignore other strangers. Even avoid those who owe money and are still not available.
However, this seemingly simple task is not so easy to implement for the machine.
For a computer, an image of a picture, whether it is a static picture or a frame in a dynamic video, is a matrix of pixels. For example, a 1080p digital image is a matrix consisting of 1980*1080 pixels. Each pixel, if it is an 8-bit rgb format, is three numbers ranging from 0-255.
In the data, the machine needs to find out which part of the data represents the concept: which part of the data is the cup, which part is the book, and which part is the face, which is the rough classification problem in visual pattern recognition.
Face recognition, in the part of the data that all machines consider to be human faces, distinguishes who this face belongs to. This is a fine classification problem.
How many types of faces can be divided into?
Depending on the size of the face database of the problem being processed, how many target faces are in the face database, the machine needs to perform a corresponding number of fine classifications. If you want the machine to recognize everyone he sees, how many people in the world can be divided into categories, and the differences between these categories are very subtle. This shows the difficulty of the face recognition problem.
Not to mention, this matter is also affected by various factors such as lighting, angles, and decorative objects on the face. This is not difficult to explain why face recognition technology has not been widely used in daily life, and most people can only contact face recognition in science fiction movies.
Silly and unclear - some concepts that are easily confused
Some things that are less familiar are often accompanied by a lot of conceptual confusion.
For example, Chinese people who don't know much about Western religion may not know why some people believe in God but don't believe in Jesus. They are all uncles working in churches. Why do they want to abstain from sex and some can get married?
As a new thing, face recognition is accompanied by a lot of conceptual confusion, and distinguishing these concepts is still important for understanding face recognition.
Take a deep breath, close your eyes, the world has the freshest oxygen ... Yu Quan's "Deep Breath" is well known to us, but as the environmental problems become more and more serious, the haze sky also increases, PM2.5 PM10 and so on Vocabulary has also been mentioned more and more, and air purifiers have quickly become popular on the market with this "air quality" trend. Along with this, the air-clean brand has sprung up, and various technologies are dazzling. Which ones are indeed effective and which are just tasteless propaganda? How does the Air Purifier bother us to get rid of pollution? And look at the editors for you.
Analysis of air purifier
The critical value of PM2.5 content is 75 μg / m3
The pollutants in the air mainly include soot, total suspended particulates, inhalable particulates (PM2.5) and fine particulates (PM10). The smaller the diameter of the particulates, the deeper the part that can enter the respiratory tract. 10 micron diameter particles It is deposited in the upper respiratory tract, and particles below 2 microns can penetrate 100% into the bronchiole and alveoli.
1k-5k air purifier prices vary greatly
The air purifier products on the market not only have various functions, but also have prices ranging from thousand yuan to tens of thousands. The pricing of imported products is generally higher than that of domestic brands. Except for the core technology of many brands, the promotion of purification effects is similar, and consumers need to choose according to demand.
The air quality standard of 74 key cities is only 4.1%
According to the data of the press conference held by the State Council Information Office on June 4, according to the new "Ambient Air Quality Standards", the six pollutants SO2, NO2, PM10, PM2.5, CO and O3 were evaluated, 74 new standards In the first phase of monitoring and implementation, the proportion of cities that met the ambient air quality standards was only 4.1%, and the other 256 cities implemented the old air quality standards, and the proportion of cities that met the standards was 69.5%.
Air purifier sales increased by 90.5% compared with last year
According to a report recently released by the China Electronics and Information Industry Development Institute, due to the haze weather, air purifiers have become the most concerned home appliance products, with sales of nearly 2.4 million units nationwide last year, a year-on-year increase of 90.5%; retail The amount reached 5.6 billion yuan, a year-on-year increase of 105.9%.
HEPA filter needs to be replaced in March
The filter of the air purifier is the same as the filter of the water purifier, and it is not effective for a long time. After long-term use, the accumulation of dust on the surface of the filter will also cause the filter to gradually fail. Therefore, when the haze is more serious, the non-washable HEPA filter needs to be replaced every three months.
Merchants claim that the purification rate is more than 99% for the concept of stealing
99% or even 99.99% seems to have become a slogan for many air purifiers on the market. Many brands of products promote their high removal rate of PM2.5 and formaldehyde. In fact, this kind of publicity is more of a kind. The slogan of stealing the concept, the removal rate of 99% is the effect of the material itself on PM2.5 and formaldehyde, not the effect of actually running in space.
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