03/04/2020- Bipasha Banerjee – Combining Crowdsourcing and Google Street View to Identify Street-level Accessibility Problems

Summary

The paper by Hara et al. attempts to address the problem of sidewalk accessibility by using crowd workers to label the data. The authors had different contributions in addition to just making crowd workers label images. They conduct two studies, a feasibility study and an online crowdsourcing study using AMT. The first study aims to find out how practical it is to label sidewalks using reliable crowd workers (experts). This study also gives an idea of the baseline performance and acts as a validated ground truth data. The second study aims to find out the feasibility of using Amazon Mechanical Turks for this task. They have evaluated the accuracy of image-level as well as pixel-level. The authors have conducted a thorough background study on the current sidewalk accessibility issues, the current audit methods, and that of crowdsourcing and image labeling. They were successful in showing that untrained crowd workers could identify and label sidewalk accessibility issues correctly in the google street view imagery. 

Reflection

Combining crowdsourcing and google street view to identify street- level accessibility is essential and useful for people. The paper was an interesting read and the authors described the system well. In the video[1], the authors show the instructions for the workers. The video gave a fascinating insight into how the task was designed for the workers, explaining every labeling task in detail. 

The paper mentions accessibility, but they have restricted their research for wheelchair users. This works for the first study as they are able to label the obstacles correctly, and this gives us the ground truth data for the next study as well as establishes the feasibility of using crowd workers to identify and label accessibility effectively. However, accessibility problems on sidewalks are also faced by other groups like people with reduced vision, etc. I am curious to see how the experiments would differ if the user-group and the need changes?

The experiments are based on google street view, which is not known to be the best at certain times. There are certain apps that help people get real-time updates on traffic while driving like the app Waze [2]. I was wondering if google maps or any other app insert dynamic updates for street walks, it would be beneficial. It would not only help people but also help the authority in determining which sidewalks are frequently used and the most common issues people face. The paper is a bit old. But, newer technology would surely help users. The paper [3] by the same author is a massive advancement in collecting sidewalk accessibility data. This paper is a good read based on the latest technology.

The paper mentions that active feedback to crowd workers would help improve labeling tasks. I think that dynamic, real-time feedback would be immensely helpful. However, I do understand that it is challenging to implement when using crowd workers, but an internal study could be conducted. For this, a pair or more people need to work simultaneously, where one label and the rest give feedback or some other combinations. 

Questions

  1. Sidewalk accessibility has been discussed for people with accessibility problems. They have considered people in wheelchairs for their studies. I do understand that such people would be needed for study 1, where labeling is a factor. However, how does the idea extend to people with other accessibility issues like reduced vision?
  2. This paper was published in 2013. The authors do mention in the conclusion section that with improvement in GSV and computer vision will overall help. Has any further study been conducted? How much modification of the current system is needed to accommodate the advancement in GSV and computer vision in general? 
  3. Can dynamic feedback to workers be implemented? 

References 

[1] https://www.youtube.com/watch?v=aD1bx_SikGo

[2] https://www.waze.com/waze

[3] http://kotarohara.com/assets/Papers/Saha_ProjectSidewalkAWebBasedCrowdsourcingToolForCollectingSidewalkAccessibilityDataAtScale_CHI2019.pdf

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03/04/2020 – Nurendra Choudhary – Real-time captioning by groups of non-experts

Summary

In this paper, the authors discuss a collaborative real-time captioning framework called LEGION:SCRIBE. They compare their system against the previous approach called CART and Automated Speech Recognition (ASR) system. The authors initiate the discussion with the benefits of captioning. They proceed to explain the expensive cost of hiring stenographers. Stenographers are the fastest and most accurate captioners with access to specialized keyboards and expertise in the area. However, they are prohibitively expensive (100-120$ an hour). ASR is much cheaper but their low accuracy deems them inapplicable in most real-world scenarios. 

To alleviate the issues, the authors introduce SCRIBE framework. In SCRIBE, crowd-workers caption smaller parts of the speech. The parts are merged using an independent framework to form the final sentence. The latency of the system is 2.89s, emphasizing its real-time nature, which is a significant improvement over ~5s of CART.

Reflection

The paper introduces an interesting approach to collate data from multiple crowd workers for sequence learning tasks. The method has been applied before in cases such as Google Translate (translating small phrases) and ASR (voice recognition of speech segments). However, SCRIBE distinguishes itself by bringing in real-time improvement in the system. But, the system relies on the availability of crowd workers. This may lead to unreliable behaviour in the system. Additionally, the hired workers are not professionals. Hence, the quality is affected by human behavioral features such as mindset, emotions or mental stamina. I believe a study on the evolution of SCRIBE overtime and its dependence on such features needs to be analyzed.

Furthermore, I question the crowd management system. Amazon MT cannot guarantee real-time labourers. Currently, given the supply of workers with respect to the tasks, workers are always available. However, as more users adopt the system, this need not always hold true. So, crowd management systems should provide alternatives that guarantee such requirements. Also, the work provider needs to find alternatives to maintain real-time interaction, in case the crowd fails. In case of SCRIBE, the authors can append an ASR module in a situation of crowd failure. ASR may not give the best results but would be able to ensure smoother user experience.

The current development system does not consider the volatility of crowd management systems. This makes them an external single point of failure. I think there should be a push in the direction of simultaneously adopting multiple management systems for the framework to increase their reliability. This will also improve system efficiency because it has a more diverse set of results as choice. Thus benefiting the overall model structure and user adoption. 

Questions

  1. Google Translate uses a similar strategy by asking its users to translate parts of sentences. Can this technique be globally applied to any sequential learning framework? Is there a way we can divide sequences into independent segments? In case of dependent segments, can we just use a similar merging module or is it always problem-dependent?
  2. The system depends on the availability of crowd workers. Should there be a study on the availability aspect? What kind of systems would be benefitted from this?
  3. Should there be a new crowd work management system with a sole focus on providing real-time data provisions?
  4. Should the responsibility of ensuring real-time nature be on the management system or the work provider? How will it impact the current development framework?

Word Count: 567

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03/04/20 – Lulwah AlKulaib- SocialAltText

Summary

The authors propose a system to generate Alt text for images embedded in social media posts by utilizing crowd workers. Their goal is to have a better experience for the blind and visually impared (BVI) when using social media. Existing tools provide imperfect descriptions some by automatic caption generation, and others by object recognition. These systems are not enough as in many cases their results aren’t descriptive enough for BVI users. The authors study how crowdsourcing can be used for both:

  • evaluating the value provided of existing automated approaches
  • Enabling workflows that provide scalable and useful alt text for BVI users

They utilize real-time crowdsourcing to test experiments with varied depth levels of interaction of the crowd in assisting visually impaired users. They show the shortcomings of existing AI image captioning systems and compare them with their method. The paper suggests two experiences:

  • TweetTalk: is a conversational assistant workflow.
  • Structured Q&A: that builds upon and enhances the state of the art generated captions.

They evaluated the conversational assistant with 235 crowdworkers. They evaluated 85 tweets for the baseline image caption, each tweet was evaluated 3 times with a total of 255 evaluations.

Reflection

The paper presents a novel concept and their approach is a different take on utilizing crowdworkers. I believe that the experiment would have worked better if they tested it on some visually impared users. Since the crowdworkers hired were not visually impaired, it makes it harder to say that BVI users would have the same reaction. Since the study targets BVI users, they should have been the pool of testers. People interact with the same element in different ways and what they showed seemed too controlled. Also, the questions were not all the same for all images, which makes this harder to generalize. The presented model tries to solve a problem for social media photos and not having a plan to repeat for each photo might make interpreting images difficult. 

I appreciated the authors’ use of existing systems and their attempt at improving the AI generated captions. Their results obtain better accuracy compared to state of the art work.

I would have loved seeing how different social media applications measured compared with each other. Since different applications vary in how they present photos. Twitter for example gives a limited amount of character count while Facebook could present more text which might help BVI users in understanding the image better. 

In the limitations section, the authors mention that human in the loop workflows raise privacy concerns and that the alt text would generalize to friendsourcing and utilizing social network users. I wonder how that generalizes to social media applications in real time. And how reliable would friendsourcing be for BVI users.

Discussion

  • What are improvements that you would suggest to better the TweetTalk experiment?
  • Do you know of any applications that use human in the loop in real time?
  • Would you have any privacy concerns if one of the social media applications integrated a human in the loop approach to help BVI users?

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03/04/2020 – Ziyao Wang – Combining crowdsourcing and google street view to identify street-level accessibility problems

In this paper, the authors focused on the mechanism that using untrained crowdworkers to find and label accessibility problems in Google Street View imagery. They provide the workers images from Google Street View imagery to let them find, label and access sidewalk accessibility problems. They compared the results of this labeling task completed by six dedicated labelers including three wheelchair users and by MTurk workers. The comparison shows that the crowdworkers can determining the presence of an accessibility problem with high accuracy, which means this mechanism is promising about sidewalk accessibility. However, that mechanism still have problems such as locating the GSV camera in geographic space and selecting an optimal viewpoint, sidewalk width problem and the age of the images. In the experiments, the workers cannot label some of the images due to camera position, and the images may be captured three years ago. Additionally, there is no method to measure the width of the sidewalk, which is a need by the wheelchair users.

Reflections:

The authors combined the Google Street View imagery and MTurk Crowdsourcing to build a system which can detect accessibility challenges. This kind of hybrid system has a high accuracy in the finding and labeling of such kind of accessibility challenges. If this system can be used practically, the disables will benefit a lot with the help of the system.

However, there is some problems in the system. As is mentioned in the paper, the images in the Google Street View are old. Some of the images may be captured years ago. If the detection is based on these pictures, some new access problems will be detected. For this problem, I have a rough idea about letting the users of the system to update the image library. When they found some difference between the images from library and practical sidewalk, they can upload the latest pictures captured by them. As a result, other users will not suffer from the images’ age problem. However, this solution will change the whole system. Google Street View imagery requires professional capture devices which is not available to most of the users. As a result, the Google Street View will not update its imagery using the photos captured by the users, and the system cannot update itself using the imagery. Instead, the system has to build its own image library, which is totally different from the introduced system in the paper. Additionally, the photos provided by the users may be with low resolution, and it will be difficult for the MTurk workers to label the accessibility challenges.

Similarly, the problem that the workers cannot measure the width of the sidewalk can be solved if users can upload the width when they are using the system. However, it still faces the problem of lacking an own database and the system needs to be modified hugely.

Instead of detecting accessibility challenges, I think the system is more useful in tracking and labeling bike lanes. Compared with the accessibility of sidewalk, to detect the existence of bike lanes will suffer less from the age problem, because even the bike lanes were built years ago, they can still work. Also, there is no need to measure the width of the lanes, as all the lanes should have enough space for bikes to pass.

Question:

Is there any approach to solve the age problem, camera point problem and measuring width problem in the system?

What do you think about applying such a system to track and label bike lanes?

What other kinds of street detection problems can this system being applied to?

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03/04/2020- Ziyao Wang – Real-time captioning by groups of non-experts

Traditional real-time captioning tasks are completed by professional captionists. However, the cost to hire them is expensive. Alternatively, some automatic speech recognition systems have been developed. But there is still problem that these systems perform badly when the audio quality is low or there are multiple people talking. In this paper, the authors developed a system which can hire several non-expert workers to do the caption task and merge their works together to obtain a high accuracy caption output. As the workers have a significant lower salary compared with the experts, the cost will be reduced even multiple workers are hired. Also, the system has a good performance collecting workers’ jobs and merging them to get a high accuracy output with low latency.

Reflections:

When solving problems with the requirement of high accuracy and low latency, I always hold the view that only AI or experts can complete such kind of tasks. However, in this paper, the authors showed us that non-experts can also complete this kind of tasks if we can have a group of people work together.

Compared with the professionals, hiring non-experts will cost much less. Compared with AI, people can handle some complicated situations better. This system combined this two advantages and provided a cheap real-time captioning system with high accuracy.

It is for sure that this system has lots of advantages, but we should still consider it critically. For the cost, it is true that hiring non-experts will spend much less than hiring professional captionists. However, the system needs to hire 10 workers to get 80 to 90 percentage accuracy. Even though the workers have a low salary, for example 10 dollars per hour, the total cost will reach 100 dollars per hour. Hiring experts will only cost around 120 dollars for one hour, which shows that the saving of applying the system is relatively low.

For the accuracy part, there is possibility that all the 10 workers missed a part of the audio. As a result, even merging all the results provided by the workers, the system will still miss this part’s caption. Instead, though the AI system may provide caption with errors, the system can at least provide something for all words in the audio.

For these two reasons, I think hiring less workers, for example three to five workers, to fix the errors in the system generated caption will save more money while the system can still maintain high accuracy. And with the provided caption, the workers’ tasks will be easier, and they may provide more accurate results. Also, for the circumstances in which AI system performs well, the workers will not need to spent time typing, and the latency of the system will be reduced.

Questions:

What are the advantages of hiring non-expert humans to do the captioning compared with the experts or AI systems?

Will a system hiring less workers to fix the errors in the AI generated caption be cheaper? Will this system perform better?

For the system mentioned in the second question, does it have any limitations or drawbacks?

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03/04/2020 – Palakh Mignonne Jude – Combining Crowdsourcing and Google Street View To Identify Street-Level Accessibility Problems

SUMMARY

The authors of this paper aim to investigate the feasibility of recruiting MTurk workers to label and assess sidewalk accessibility problems as can be viewed by making use of Google Street View. The authors conducted two studies, the first, with 6 people (3 from their team of researchers and 3 wheelchair users) and the second, that investigated the performance of turkers. The authors created an interactive labeling interface as well as a validation interface (to help users to accept/reject previous labels).  The authors proposed different levels of annotation correctness comprising of two spectra – localization spectrum which includes image level and pixel level granularity and specificity spectrum which includes the amount of information evaluated for each label. They defined image-level correctness in terms of accuracy, precision, recall, and f-measure. In order to computer inter-rater agreement at the image-level, they utilized Fleiss’ kappa. In order to evaluate the more challenging pixel-level agreement, they aimed to verify the labeling by indicating that pixel-level overlap was greater between labelers on the same image versus across different images. The authors used the labels produced from Study 1 as the ground truth dataset to evaluate turker performance. The authors also proposed two quality control approaches – filtering turkers based on a threshold of performance and filtering labels based on crowdsourced validations.

REFLECTION

I really liked the motivation of this paper especially given the large number of people that have physical disabilities. I am very interested to know how something like this would extend to other countries such as India as it would greatly aid people with physical disabilities over there since there are many places with poor walking surfaces and do not have support for wheelchairs. I think that having such a system in place in India would definitely help disabled people be better informed about places that can be visited.

I also liked the quality control mechanisms of filtering tuckers and filtering labels since these appear to be good ways to improve the overall quality of the labels obtained. I thought it was interesting that the performance of the system improved with tucker count but the gains diminished in magnitude as the group size grew. I thought that the design of the labelling and verification interface was good and that it made it easy for users to perform their tasks.

QUESTIONS

  1. As indicated in the limitations section, this work ‘ignored practical aspects such as locating the GSV camera in geographical space and selecting an optimal viewpoint’. Has any follow-up study been performed that takes into account these physical aspects? How complex would it be to conduct such a study?
  2. The authors mention that image quality can be poor in some cases due to a variety of factors. How much of an impact would this cause to the task at hand? Which labels would have been most affected if the image quality was very poor?
  3. The validation of labels was performed by crowd workers via the verification interface. Would there have been any change in the results obtained if experts had been used for the validation of labels instead of crowd workers (since they may have been able to identify more errors in the labels as compared to normal crowd workers)?

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03/04/20 – Akshita Jha – Pull the Plug? Predicting If Computers or Humans Should Segment Images

Summary:
“Pull the Plug? Predicting If Computers or Humans Should Segment Images” by Gurari et. al. talks about image segmentation. They propose a resource allocation framework that tries to predict when best to use a computer for segmenting images and when to switch to humans. Image segmentation is the process of “partitioning a single image into multiple segments” in order to simplify the image into something that is easier to analyze. The authors implement two systems that decide when to replace humans with computers to create fine-grained segments and when to replace computers with humans in order to get coarse segments. They demonstrate through experiments that this mixed model of humans and computers beats the state of the art systems for image segmentation. The authors use the resource allocation framework, “Pull the Plug”, on humans or computers. They do this by giving the system an image and trying to predict if an annotation should from a human or a computer. The authors evaluate the model using Pearson’s correlation coefficient (CC) and mean absolute error (MAE). CC indicates the correlation strength of the predicted score to the actual scores given by the Jaccard index on the ground truth. MAE is the average prediction errors. The authors thoroughly experiment with initializing segmentation tools and reducing human effort initialization.

Reflections:
This is an interesting work that successfully makes uses of mixed modes involving both humans and computers to enrich the precision and accuracy of a task. The two methods that the authors design for segmenting an image was particularly thoughtful. First, given an image, the authors design a system that tries to predict whether the image requires fine-grained segmentation or coarse-grained segmentation. This is non-trivial as this task requires the system to possess a certain level of “intelligence”. The authors use segmentation tolls but the motivation of the system design is to remain agnostic to these particular segmentation tools. The systems rank several segmentation tools by using a tool designed by the authors to predict the quality of the segmentation. The system then allocates the available human budget to create coarse segmentations. The second system tries to capture whether an image requires fine-grained segmentation or not. They do this by building on the coarse segmentation given by the first system. The second system refines the segmentation and allocates the available human budget to create fine-grained segmentation for low predicted quality segmentations. Both these tasks rely on the system proposed by the authors to predict the quality of candidate segmentation.

Questions:
1. The authors rely on their proposed system of predicting the quality of candidate segmentations. What kind of errors do you expect?
2. Can you think of a way to improve this system?
3. Can we replace the segmentation quality prediction system with a human? Do you expect the system to improve or would the performance go down? How would it affect the overall experience of the system?
4. In most such systems, humans are needed only for annotation. Can we think of more creative ways to engage humans while improving the system performance?

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Subil Abraham – 03/04/2020 – Real-time captioning by groups of non-experts

This paper pioneers the approach of using crowd work for closed captioning systems. The scenario they target is classes and lectures, where a student can hold up their phone and record the speaker and the sound the transmitted to the crowd workers. The sound that is passed is given as bite sized pieces for the crowd workers to transcribe, and the paper’s implementation of the multiple sequence alignment algorithms takes those transcriptions and combines them. The focus of the tool is very much on real-time captioning so the amount of time a crowd worker can spend on a portion of sound is limited. The authors design interfaces on the worker side to promote continuous transcription, and on the user side to allow them to correct the received transcriptions in real time, enhancing the quality further. The authors had to deal with interesting challenges in resolving errors in the transcription, which they did by a combination of comaparing transcriptions of the same section from different crowd workers, using bigram and trigram data to validate the word ordering. Evaluations showed that precision was stable while coverage increased with increase in the number of workers, while having lower error rate compared to automatic transcription and untrained transcribers.

One thing that needs to be pointed out about this work is that I believe that ASR is always rapidly improving and has made significant strides from when this paper was published. From my own anecdotal experience, Youtube’s automatic closed captions are getting very very close to being fully accurate (however, thinking back on our reading of the Ghost Work book at the beginning of the semester, I wonder if Youtube is cheating a bit and using crowd work intervention for some their videos to help their captioning AI along). I also find that the author’s solution for merging the transcriptions of the different sound bites is interesting. How they would solve that was the first thing that was on my mind because it was not going to be a matter of simply aligning the time stamps because those were definitely going to be imprecise. So I do like their clever multi part solution. Finally, I was a little surprised and disappointed that the WER was at ~45% which was a lot higher than I expected. I was expecting the error rate to be a lot closer to professional transcribers but unfortunately not. The software still has a way to go in that.

  1. How could you get the error rate down to the professional transcriber’s level? What is going wrong there that is causing it to be that high?
  2. It’s interesting to me that they couldn’t just play isolated sound clips but instead had to raise and lower volume on a continuous stream for better accuracy. Where are the other places humans work better when they have a continuous stream of data rather than discrete pieces of data?
  3. Is there an ideal balance between choosing precision and coverage in the context of this paper? This was something that also came up in last week’s readings. Should the user decide what the balance should be? How would they do it when there can be multiple users all at the same location trying to request captioning for the same thing?

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Subil Abraham – 03/04/2020 – Pull the Plug

The paper proposes a way of solving the issue of deciding when a computer or human should do the work of foreground segmentation of images. Foreground segmentation is a common task in computer vision where the idea is that there is an element in an image that is the focus of the image and that is what is needed for actual processing. However, automatic foreground segmentation is not always reliable so sometimes it is necessary to get humans to do it. The important question is deciding which images you send to humans for segmentation because hiring humans are expensive. The paper proposes a machine learning method that calculates the quality of a given coarse or fine grained segmentation and decide if it is necessary to bring in a human to do the segmentation. They evaluate their framework by examining the quality of different segmentation algorithms and are able to acheive the quality equivalent to 100% human work by using only 32.5% human effort for Grab Cut segmentation, 65% human effort for Chan Vese, and 70% human effort for Lankton.

The authors have pursued a truly interesting idea in that they are not trying to create a better way of automatic image segmentation, but rather creating a way of determining if the auto image segmentation is good enough. My initial thought was couldn’t something like this be used to just make a better automated image segmenter? I mean, if you can tell the quality, then you know how to make it better. But apparently that’s a hard enough problem that it is far more helpful to just defer to a human when you predict that your segmentation quality is not where you want it. It’s interesting that they talk about pulling the plug on both computers and humans but the focus of the paper seems to be focused on pulling the plug on computers i.e. the human workers are the backup plan in case the computer can’t do the quality work and not the other way around. This applies to both their cases, coarse grained and fine grained segmentation work. I would like to see future work where the primary work is done by humans first and then test to see how pulling the plug on the human work would be effective and where the productivity would increase. This would have to be work in something that is purely in the human domain (i.e. can’t use regular office work because that is easily automatable).

  1. What are examples of work where we pull the plug on the human first, rather pulling the plug on computers?
  2. It’s an interesting turn around that we are using AI effort to determine quality and decide when to bring humans in, rather than improving the AI of the original task itself. What other tasks could you apply this, where there are existing AI methods but an AI way of determining quality and deciding when to bring in humans would be useful?
  3. How would you set up a segmentation workflow (or another application’s workflow) where when you pull the plug on the computer or human, you are giving the best case result to the other for improvement, rather than starting over from scratch?

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03/04/2020 – Pull the Plug? Predicting If Computers or Humans Should Segment Image – Yuhang Liu

Summary:

This paper examines a new image segmentation method. Image segmentation is a key step in any image analysis task. There have been many methods before, including low-efficiency manual methods and automated methods that can produce high-quality pictures, but these methods have certain disadvantages. The authors therefore propose a distribution framework that can predict how best to assign fixed labor to collect higher quality segmentation for a given image and automated method. Specifically, the author has implemented two systems, which can perform the following processing on images when doing image segmentation:

  1. Use computers instead of humans to create the rough segmentation needed to initialize the segmentation tool,
  2. Use computers to replace humans to create the final fine-grained segmentation. The final experiments also proved that relying on this hybrid, interactive segmentation system can achieve faster and more efficient segmentation.

Reflection:

Once, I did a related image recognition project. Our subject is a railway turnout monitoring system based on computer vision, which is to detect the turnout of the railroad track from the picture, and the most critical step is to separate the outline of the railroad track. At that time, we only using the method of computer separation, the main problem we encountered at the time was that when the scene became complicated, we would face to complex line segments, which would affect the detection results. As mentioned in this paper, using human-machine, the combined method can greatly improve the accuracy rate. I very much agree with it, and hope that one day I can try it myself. At the same time, what I most agree with is that the system can automatically assign work instead of all photos going through a same process. For a photo, only the machine can participate, or artificial processing is required. This variety of interactive methods, It is far more advantageous than a single method, which can greatly save workers’ time without affecting accuracy, and the most important point is that complex interaction methods can adapt to process more diverse pictures. Finally, I think similar operations can be applied to other aspects. This method of assigning tasks through the system can coordinate the working relationship between humans and machines, for example, in other fields, such as sound sentiment analysis and musical background separation. In these aspects, humans have the incomparable advantages of machines and can achieve good results, but it takes a long time and is very expensive. Therefore, if we can classify this kind of thinking, deal with the common working relationship between humans and machines, and give complex situations to people or pass the rough points of the machine first, then the separation cost will be greatly reduced, and the accuracy rate will not be affected, so I It is believed that this method has great application prospects, not only because of the many application directions of image separation, but we can also learn from this idea to complete more detailed analysis in more fields.

Question:

  1. Is this idea of cooperation between man and machine worth learning?
  2. Because the system defines the working range of people and machines, will the machine reduce the accuracy due to the results of human work?
  3. Does man-machine cooperation pose new problems, such as increasing costs?

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