image
image
image
image
image
image
image
 
Home --> Enabling the Disabled --> Braille Tutorial (Standard Braille) 
Search  
 

Tutorial on Standard English Braille

Logical basis for cell assignments in English Braille.
  The assignment of Braille cells to the letters of the alphabet is an important concept. Knowledge of this concept helps a sighted volunteer learn Braille with greater ease. The concept is also useful when teaching others the principles of Braille.

  Braille has been around for nearly two centuries and today, in the twenty first century, one is amazed at the foresight of those who developed the scheme of Braille codes. In essence, they had in mind the fact that Braille should not just be a means for the Blind to read but must give them the means to read just as normal persons would read a book. In other words, Braille must incorporate all the important aspects of print, in a manner that a blind person can understand the contents, exactly as a normal person reading printed text does.

  The requirement given above implies that Braille codes should also convey the structure or organization of printed text as close to what can be accomplished with a limited set of sixty three cells. We will see how logically this has been done nearly a hundred and fifty years before the advent of Information Technology. Explaining the conceptual basis can be viewed as an academic exercise as well, if we decide to bring in the computer to work with text in Braille!

Return to Top


The basis for cell assignment 

  Since we have accepted in principle that Braille should match the presentation of information in print form, The letters of the alphabet alone would not be adequate in the assignment of codes. We also need to look at punctuation symbols and other forms of presentation of text such as emphasized text, italicized text etc., besides handling issues such as hyphenation, numerals and mathematical symbols or even text in other scripts. Today, computers use nearly 96 different symbols in standard English and even this is considered inadequate compared to the rich set of characters seen in books printed more than a hundred years ago. Is it at all possible for us to accomplish this with just 63?

  Considering the fact that the purpose of text is to convey information, it is entirely acceptable that a symbol or a special letter sequence can be used in place of certain words. This idea is not new to the present generation of e-population where email messages abound in contracted words, smileys and such, all done to minimize the amount of text to be typed in to convey some information. In developing Braille codes, the idea was to assign cells such that the context in which a cell is read provides a new meaning to the cell. Thus in essence, one can dispense with many symbols if their absence would not lead to ambiguity in reading text. This way we can do away with capital letters or even numerals. Hence the starting point for the assignment of codes will be the set of 26 letters of the alphabet together with some important punctuation symbols which are deemed essential.

  We now observe that about 30 to 35 cells will be the bare minimum that can convey basic information in English. Punctuation symbols such as the period (full stop), comma, semicolon, quotation marks, parentheses, question and exclamation marks are quite important. These add upto eight symbols. The ten numerals can also be handled without extra symbols if the context in which the numeral is seen can be readily discerned. Braille uses a special cell to identify the presence of a numeral. So we have thirty five cells to be assigned. Which cells in the set of sixty three will these be?

  Logical decision making is called for at this point. If it is possible for us to do the assignment in such a way that we can easily relate the letter or symbol to the cell, learning Braille will be easier. So we now look at how the sixty three cells can be arranged geometrically into groups where cells in a group share a common property. The main idea is here is that hopefully, we will be able to associate groups of cells with groups of letters or special characters based on some criteria where groups share some common properties.

Return to Top


Grouping of cells

  The first approach is to arrange the 64 possible cells into four groups of sixteen cells. This arrangement is shown below.

  We quickly see that the sixteen patterns in the first row are repeated in the other three with one perceivable difference for each row. The first row consists of only the upper dots. The last cell in the first row does not have any dots but it is a cell by its own right, signifying a space. The second, third and fourth differ only in the lower dot positions and here too, the logical structure is evident. The second row has only dot 3, the third, dots 3,6 and the fourth dot 6.

  We will now be able to identify the row a cell belongs to, by looking at the dots at the bottom of the cell. However, our main concern is the assignment of cells to the letters and symbols seen in text. So how do we reckon a letter with the cell? For this we need to go a bit further and see if the letters and symbols can be grouped logically and these groups matched with the rows. This will be a bit tricky but surprisingly easy once we see the principle.

  We have the following sets to be assigned.

  • 26 letters of the alphabet
  • 8 punctuation symbols
  • Symbols to identify the print form in which a word appears such as Italicized, Bold, Accented etc. Roughly five of these to begin with.
  • A symbol to indicate the presence of numerals. Also extending this idea to distinguish prose from poetry.
  •   We have come up with four groups and it seems logical to assign the letters, punctuaion etc., to the four groups following some rule. But such a direct assignment runs into trouble as we see that there are twenty six letters of the alphabet which do not nicely fit into the rows. A bit of home work in discerning additional groups within the four rows will give us the desired results. This is shown in the illustration below.
    Seven categories of cells

      There are seven identifiable groups each sharing a common property among its cells. Five of these have 10 cells each and the remaining two have six and seven cells respectively. That is easy to remember.

    The first five groups, here after called lines, have ten cells each.
    The sixth has six cells.
    The seventh has seven cells.
    The sixty fourth cell does not have any dots and is counted out.
    We map the letters of the alphabet into the first three lines, in the same order of the letters with one small difference which will be explained shortly.

    We map the punctuation to a separate line.

    We map the context identifying symbols in to the sixth and seventh lines.

    The fourth line is yet to be accounted for.

      We talked about the foresight of the people who devised the Braille codes. Braille cells are large in size compared to the letters or symbols in print and so the physical area occupied by the Braille cells is several times greater than the corresponding printed text. By assigning cells to very frequently occurring letter combinations or short words, we can compress the text into fewer cells. This is precisely what has been done. But there are so many frequently occurring letter combinations. Which ones do we accommodate?

      From a linguistic analysis of text, the following have been identified as the important ones which also will not cause ambiguity when used within words.

    ch, gh, sh, th, wh, ed, er, ou, ow (two letter sequences - 9 )

    and, for, of, the, with (words, also letter sequences - 5)

    ea, be bb, con cc, dis dd, en, ff, gg, in : also occur frequently in text. We see 8 of them here. 

      We now have seven groups of letters, letter sequences, punctuation and context identifying symbols which add upto 62! The small change mentioned above in assigning the letters of the alphabet will now be explained. We pull 'w' out of the alphabet and add it to the set of 9 above to make it 10. The reason for this is based on the observation that 'w' is pronounced quite differently with a sound not having any link to its name. The 63 cells are now accounted for.
    Here is the tally of 63 items which will be coded.
  • 25 letters of the alphabet (w excluded)
  • 5 short words which are frequently used in sentences.
  • 10 letter sequences of two letters containing 'h', 'e', 'o' and 'w'.
  • 10 letter sequences with repeating letters, also accommodating many punctuation symbols to be identified from the context.
  • 6 context identifying symbols and punctuation.
  • 7 context identifying symbols including contracted representations for text strings .
  • Return to Top


    The actual assignment of codes

      Before we discuss the actual assignment, we need to understand how we can identify a cell and thus the group of letters or symbols associated with it. We have seen that five groups of 10 cells have already been identified as sharing a common feature.

      The following observations are in order.

      Group 7 is identified easily as the set of cells which do not have any dots on the left, i.e., dots 123 are absent in these cells.

      Group 6 is identified next as the set of six cells which do not have dots 1 and 2. In this group, if dot 5 is present, dot 4 will also be present.

      Group 5 is identified as 10 cells without the dots in the top row, i.e., dots 14. We must remember that cells satisfying this property will also be seen in groups 6 or 7. So a cell without dots 14 is in group 5 if it is not in group 6 or 7.

     We will now see that by committing to memory, just five basic patterns, we will be able to identify all the 63 cells as belonging to one group or other and thus decode the cell. The image below illustrates what is required to be remembered to be able to identify the 10 patterns in each of the first five groups.

    The information presented in the image is repeated below as ten combinations arranged vertically one below the other using numerals.

    1
    12

    14
    145
    15

    124
    1245
    125

    24
    25

    These ten patterns are repeated in the second, third, fourth and fifth lines. Since we already know how each line is specified, we should be in a position to associate any given cell with one of the seven lines.

      Let is put this idea to test. Where does this cell fit in?  146

      The presence of dot 1 excludes it from lines 5 , 6 and 7. Which one of the first four applies is now decided by the dots at the bottom. Dot 6 is present but not 3 and hence the cell is the third cell in the fourth line!

    Summary (The final assignments)
    line 1 - a through j
    line 2 - k through t
    line 3 - uvxyz and for of the with
    line 4 - nine two character strings and 'w'
    line 5 - different two character repetitions or punctuation symbols (In line 5 a cell may represent either of the above depending on the context)
    line 6 - mixture of context identifying symbols and letter sequences
    line 7 - Basically context identifying symbols and those used in generating contracted forms of words.
    These assignments are shown below in tabular form.

     


    Knowledge of basic principles of Braille will help you understand this tutorial better.

    Contents

    The basis for cell assignments

    Grouping of cells

    Seven groups

    Assignment of codes

    Summary


    Braille codes for Mathematics

    Over the years, Visually handicapped persons have also benefited from the use of Braille for learning mathematics. Devised by a Visually handicapped person himself, Nemeth codes permit mathematical symbols to be specified through specific sequences Braille cells which can be remembered without difficulty.
     
     

    We have a separate page describing the Nemeth coding scheme used for symbols in Mathematics. It must be stated, that Nemeth codes are based on a simple principle of the use of escape characters to specify how the cells which follow should be interpreted.



     
    Acharya Logo
    Spectacular view of Sun's rays as he emerges from the peaks of the Annapurna, Machpuchchare (Fish tail) range in the Himalayas. The text in Bharati Braille reads "shreyo bhuyaat sakalajanaanaam" which translates into "May all people be happy and prosperous.

    Today is May. 29, 2017
    Local Time: 19 23 37


    | Home | Design issues | Online Resources | Learn Sanskrit | Writing Systems | Fonts |
    | Downloads | Unicode, ISCII | SW for the Disabled | Linguistics | Contact us |
    Last updated on 10/30/12     Best viewed at 800x600 or better