Tamil billboard; credits - masanori_jpn via Flickr.

Latha vs Bamini – 1

Well, this blog post is not about any famous cat-fight: ‘sabaash – sariyaane potTi!’


Frame grab from the song ‘Kannum Kannum’ from movie ‘Vanjikottai Vaaliban’ with danseuse rivals Padmini and Vaijayanthimala.

but about the more mundane issue of resolution of Tamil letters that maybe affecting visual acuity and usage in practical things like billboards. Yes, we know Latha (is Tamil font from Microsoft) and Bamini famous storied font created in 1980s. Bamini font is also used in the Chennai Metro, Colombo railway station among other places; creator of Bamini was recently felicitated with 2017 Tamil Computing award for the pioneering efforts in the dawn of digital era.

Back to resolution; ‘kannu theriyithaa ?’ is the usual expression but it really asks the question are you able to see the object/thing/place/person – and not literally ‘do you have vision?’

In optical science, it is well known that free-space – distance – acts as a filter introducing blurs into the image. This is the mechanism behind why we don’t see details of far-away billboards and they grow in detail as one may approach them.

Tamil billboard; credits - masanori_jpn via Flickr.

Tamil billboard; credits – masanori_jpn via Flickr.

So if you are advertising in large billboards, obviously you want to be visible to audiences as far as laws of physics [Rayleigh resolution limit] will allow.

We can gather from simple considerations the following:

  1. Larger the letters farther away they maybe visible
  2. Longer wavelengths of light [Red (longer) – Violet (shorter)] farther they are visible without being scattered

So you can ask, if all the billboards are painted in large bold Tamil letters ‘adikkira maathiri’, will be visible for very long distances ? Yes. And they will also be boring.

This knowledge does not help us to choose between two fonts, since we can draw/write/pain letters in their character in any size and color – just the shape remains fixed.

Now to properly analyze the two fonts for best visual acuity, we may consider the following criteria:

  1. All letters compared need to be same in both fonts
  2. Viewer is considered to observe the projected font/printed text/billboard from progressively farther and farther distances.
  3. Essentially font corresponding to the billboard which is visible from farthest distance is the winner/better font in this criteria

Before we start drawing conclusions you also want the test subjects to have 20/20 vision or wear corrective prescription eye glasses for the same level of vision.

Now, regardless of the color and size of the fonts we can use the criteria to compare the acuity of the fonts.

But wait, can we do this by computer modeling without paint, labor and 20/20 vision subjects? You betcha! This will be subject of next blog post.

Until then…. Vaazhga Valamudan.


அன்பழகன் வாத்தியார்

எனது தமிழ் ஆசிரியர் கேட்டார் ‘சவம்-னா இறப்பின் பின் உள்ள சடலம், என்பது தெறியாதா?’ அப்பதான் ‘அன்பே சிவம்‘ என்பதை ‘அன்பே சவம்‘ என்று அவசரத்தில் எழுதியது புலபட்டது.  அன்பழகன் சார், அவருக்கு இனிமையா இதை பாடம் கற்பிக்க மட்டும் ஒரு வாய்பாகதான் தெறிஞ்சிருக்கு. அப்ப எனக்கு edit-distance by one (சிவம் -> சவம்) அதனால் வந்த வினை என தெறியாது. அவர்கையில் கற்றது வாழ்வில் ஒரு நல்ல அனுபவம்.

Today’s blog topic is spell-checking.


It is well known that Bayesian methods can be used to correct spelling error (see Prof. Daniel Jurafsky & James H. Martin book chapter); the above example (‘அன்பே சிவம்’) with real-word error (i.e. error is made not in dictionary word but semantic error) can be easily corrected if we have word level bi-gram data and uni-gram data. This can easily be collected from Tamil Wikipedia data dumps, or Project Madurai. [Hint: project tip for engineering/math/cs students].

While letter level uni, bi and tri-gram data exist for Tamil in open-tamil project and part of my work at Tamil-TTS here, this remains to be not publicly available. Once this data – made available in public-domain – can be integrated, the various Tamil spell checkers in Tamil like Rajaraman’s Vaani, Dr. Vasu Renganathan’s, and our solthiruthi can make use of it. Potentially hunspell, aspell tools can be updated at their suggestion level modules to provide appropriate suggestions.

Future generations will never know of ‘அன்பே சவம்’. 🙂


San José, CA