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Captcha Alternative for Visually Impaired

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Why is there a requirement for Captcha Alternative for Blind?

  • Currently, We do have some browsers in the market which are being used by the blind people like (
  • These browsers use Screen Readers to browse the web.
  • These Screen Reader Programs tend to talk over the Audio Captcha as the user navigates between the audio playback controls and answer box which in turn makes it difficult for the user to hear the Captcha.
  • The blind user must also memorize the sequence of random numbers or words as said in the audio to be able to enter it correctly.
  • The most common Audio Captchas have less than 50% success rate due to Intrinsic difficulty of interpreting the noisy sound file.

My Approach for this Problem

  • I have used OCR technique to convert recognized image Captchas which are then converted into readable and editable text and then into Morse code which in turn produces vibrations in the Mobile App.
  • I have used vibration Captcha instead of audio Captcha as they are much more secure and accurate.
  • Vibration Captchas are an advantage in overcoming the noise problems faced in audio Captchas.

Why Vibration Captchas?

  • Visually Impaired people face a lot of problems while authenticating the Captcha.
  • In some applications OTP is provided to us as an alternative solution but it is not provided in all the apps.
  • In some apps audio Captchas are also provided but many citizens find it difficult to decipher as audio Captchas are more difficult than visual Captchas for blind users who use Screen-Reader programs.

Approach Implementation

Flow of the Approach

Idea Approach


  • When the user visits any Website he comes across the Homepage. Then he moves to the login Menu where he is asked to fill the form.
  • As soon as he encounters any Captcha, an Extension is triggered.
  • Another Webpage is opened which acts as an Extension to any Website encountering Captchas.
  • The extension asks the user if he wants to read the captcha through vibrations.
  • If he says No the extension is closed. If he says Yes the Website immediately connects to a Mobile Application.
  • This Mobile App is developed using Android Studios.
  • The Image Captcha conversion to text takes place in the back end of the app through Optical Character Recognition technique.
  • The OCR code is such that hackers will not be able to catch on and create bots that would bypass this test. The OCR code is developed in such a way that it provides maximum accuracy.
  • The text is then converted to Morse code. The Morse code is written using JavaScript. It is a tool used in telecommunications to encode text characters called Dots and Dashes, as uniform sequences of two separate signal durations.
  • In the Morse code, each alphabet and number is assigned a unique pattern using dots and dashes. The length of a dash is three times that of a dot..
  • Inside a character, each dot or dash is accompanied by a time of signal absence called space.
  • The pattern is defined in a way to distinguish between Lowercase Alphabets and Uppercase Alphabets by using Extra Spaces.
  • The Morse code then produces vibrations which are to be sensed by the visually impaired to enter the text on the website.
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Last Updated : 05 Jul, 2022
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