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What is Data Labelling? - PerfectionGeeks

What is Data Labelling and How to Do It Efficiently?

May 04, 2022 12:10 PM

Data Labelling

What is data labeling?

In machine learning, data labeling is the methodology of determining raw data (images, text files, videos, etc.) and adding one or more significant and informative titles to deliver context so that a machine learning model can understand it. For instance, labels might suggest whether a photo has a bird or car, which words were uttered in an audio recording, or if an x-ray has a tumor. Data labeling is needed for several use cases including computer vision, natural language processing, and speech recognition.

How does data labeling work?

Today, most suitable machine learning models use directed learning, which spreads an algorithm to map one input to one output. For supervised learning to function, you require a labeled set of data that the representative can learn from to make the right decisions. Data labeling generally starts by questioning humans to make judgments about a given amount of unlabeled data. For instance, labelers may be asked to tag all the pictures in a dataset where “does the picture contain a bird” is right. The tagging can be as rough as a straightforward yes/no or as granular as determining the exact pixels in the image associated with the bird. The machine learning model uses human- provided labels to learn the underlying patterns in a process called "model training." The effect is a trained model that can be used to make predictions on new data.

In machine learning, a properly labeled dataset that you operate as the factual standard to teach and evaluate a given model is often called “ground truth.” The precision of your prepared model will rely on the precision of your ground truth, so spending the time and resources to assure highly accurate data labeling is crucial.

Approaches to data labeling

As noted above, data labeling is a time-consuming process that needs an eye for detail. Based on the situation information, the amount of data that is to be tagged, the sophistication of data, and the style, the technique used to annotate data will vary.

Let’s examine various approaches that your business can opt for based on the financial resources and available time.

In-house data labeling

Based on the industry type, time in hand to achieve the given AI project, and the availability of needed resources, the data label process can be performed in-house by the organizations.


  • High accuracy
  • Simplified tracking
  • High-quality


  • Need extensive resources
  • Time-consuming/slow

Sourcing data sets that are labeled by freelancers are available on several crowdsourcing platforms. This process can be used for annotating generalized data like photographs.

The most prominent example of data labeling through crowdsourcing is Recaptcha. The user is asked to determine distinct types of pictures to verify that they are humans. These are confirmed based on the inputs given by other users. This works as a database of brands for an array of images.


  • Fast and easy
  • Cost-effective


  • Cannot be utilized for data that need domain expertise
  • Quality is not guaranteed

Outsourcing can work as a midway between in-house data labeling and crowdsourcing. Hiring third-party institutions or individuals with domain expertise can help the company with all – long-term and short-term projects.


  • Optimal for high-level temporary projects
  • Third-party outsourcing businesses provide vetted staff
  • Provides both pre-built and custom data labeling tools as per your business requirements
  • Can get the chance of niche-specific data labeling professionals


  • Managing the third party can be time-consuming

One of the most delinquent forms of data labeling and annotation that is widely utilized and accepted by enterprises is machine-based annotation. Automating the data labeling process with the use of data labeling software, facilitates human intervention and boosts the rate at which labeling can be done. With the process called active learning, data can be tagged based on which the tags can be added to training datasets automatically.


  • More rapid data processing and labeling
  • Involves lesser human intervention


  • Although better rate but not at par with human tagging
  • In case of mistakes, human intervention is still needed.

What are some common types of data labeling?

Computer Vision: When making a computer vision system, you first require to label pictures, pixels, or key points, or make a boundary that completely holds a digital image, known as a bounding box, to develop your training dataset. For instance, you can organize images by quality style (like product vs. lifestyle images) or content (what’s actually in the image itself), or you can segment an image at the pixel level. You can then use this activity data to make a computer vision model that can be used to automatically classify images, notice the location of objects, identify key points in an image, or segment an image.

Natural Language Processing: Natural language processing requires you to preferably manually identify vital sections of text or tag the text with particular labels to develop your training dataset. For instance, you may like to identify the sentiment or intent of a text blurb, recognize parts of speech, classify proper nouns like businesses and people, and place text in images, PDFs, or other files. To do this, you can draw bounding bins around text and then manually transcribe the text in your training dataset. Natural language processing models are used for sentiment analysis, entity name recognition, and optical character recognition.

Audio Processing: Audio processing transforms all types of sounds such as wildlife noises (barks, whistles, or chirps), speech, and building sounds (breaking glass, scans, or alarms) into a structured form so it can be used in machine learning. Audio processing often needs you to first manually transcribe it into written text. From there, you can discover deeper knowledge about the audio by adding tags and categorizing the audio. This classified audio becomes your training dataset.

What are some best practices for data labeling?

There are multiple techniques to enhance the efficiency and accuracy of data labeling. Some of these techniques include:

  • Intuitive and streamlined task interfaces to help minimize cognitive burden and context switching for human labelers.
  • Labeler consensus to help counteract the error/bias of individual annotators. Labeler consensus applies by sending each dataset object to multiple annotators and then consolidating their responses (called “annotations”) into a single label.
  • Label auditing to confirm the precision of labels and update them as required.
  • Active learning makes data labeling more efficient by using machine learning to determine the most useful data to be labeled by humans.

How can data labeling be done efficiently?

Successful machine learning measures are developed on the shoulders of big volumes of high-quality training data. But, the process to make the training data required to make these models is often expensive, complicated, and time-consuming. The bulk of models created today needs a human to manually label data in a way that allows the model to learn how to make correct decisions. To overcome this challenge, labeling can be made more efficient by using a machine learning model to label data automatically.

In this procedure, a machine learning model for labeling data is first trained on a subset of your raw data that has been labeled by humans. Where the labeling model has high trust in its outcomes based on what it has learned so far, it will automatically apply labels to the basic data. Where the labeling model has lower trust in its developments, it will pass the data to humans to do the labeling. The human- generated labels are then provided back to the labeling ideal for it to learn from and enhance its ability to automatically label the next set of raw data. Over time, the model can label more and more data automatically and substantially speed up the design of training datasets.

Conclusion: Use a Blended Approach

After exploring multiple methods to label data for machine learning, we suggest a blended approach: using both automated and external data labeling.

There may be some data security threats with external labeling, but in most cases, the data to be labeled is not sensitive. In such systems, external data labeling along with some type of automated data labeling is the best option to achieve high-quality labeled data cheaply and fastly.

Luckily for us, some organizations such as Amazon, Scale AI, and Label box have recognized gaps in labeling and presented a plethora of combinations within their services that can help you attain your preferred labeled dataset and within your Service Level Agreement.

These service offerings have developed a streamlined approach that incorporates crowd-based data labeling with automated machine learning so that you can maintain a smooth pipeline-building experience.

To make sure that labeling tasks are accurate and comply with the standards of the customers, their approach is to work with the client specialists promptly for quality assessments, thus gaining confidence in the information that has been labeled to compensate for the lack of oversight.

Is your information causing you headaches? Whether the data is labeled, unlabeled, structured, or unstructured, contact PerfectionGeeks Technologies Machine learning practice is here to help!

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