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Information Technologies for Visually Impaired People
a) b) c)
Figure 3 : Structure of a Braille Character. a) Generator
Symbol, b) Letter “a”, c) Number “1”.
concepts of reality. Moreover, the system cleans up the introduced
hand drawn predefined shapes, improving the final
appearance of an edited document.
From a scientific point of view both applications belong
to the two main lines of the Document Analysis research
field stated in the above paragraphs: text and graphics
analysis. The aim of the translation of Braille texts is a
particular case of OCR named OBR (Optical Braille Recognition)
[5] and the interactive recognition of graphical
shapes designed by means of a digital tablet, is a case of
graphical symbol recognition [3].
In the rest of the paper we further explain both applications
and their technological basis. Section 2 presents the
Braille translator, Section 3 explains the application of
graphical shape recognition, and finally Section 4 is devoted
to the conclusions.
2 Translator from Braille to View
In this section we present the framework wherein the
application has been developed and some of the technological
principles forming the basis of its construction.
2.1Purpose and Application Framework
Unlike the majority of other published systems which
use papers made by a Braille printer, the system presented
in this paper works with handwritten documents by means
of a Perkins typewriter, see Figure 1. Nowadays, a visually
impaired child who has not yet started to use a computer to
create his/her documents, uses this kind of typewriter. When
the child is integrated into a school where neither teachers
nor students are able to understand Braille, someone has to
translates these documents, in order for them to be shared
or evaluated. This task is done by assistant teachers who go
to the schools periodically. A simultaneous translation of
these papers allows the children to share them with their
environment in a more dynamil way. Their teachers can
correct their homework or exams in a more direct and agile
way, and they can give their marks at the same time as the
rest of the students. Their classmates can understand their
homework and this facilitates the integration of the child
with them. Finally their families can also follow up the
progress of their children as they can understand their homework.
The system presents another more generic advantage,
the possibility to "photocopy" a Braille text. To duplicate a
Braille text means that it has to be reprinted with its relief
necessitating recognition of the original text and reprint it
with relief. Nowadays this process can only be done by
manually retyping the text, but with this system it is possible
to scan, analyze and save the text in a digital format
without retyping it.
The system consists of a personal computer connected
to a scanner. Directly from the application it is possible to
scan a Braille document, recognize the Braille characters
and translate them. The Braille notation has different interpretation
styles. Thus it allows writing, apart from plain text,
music, chemical symbols, mathematical formulae, etc. Each
of these domains has its own symbols and placement rules,
and some common symbols that have different meanings
depending on the domain in which they appear. It allows a
code based in six dots to have a high representational power
(There is another codification based on eight dots which is
not considered in this paper). However, since the analyzed
documents are made by little children using a Perkins typewriter,
the possibility exists of having some imperfections
such as "deleted" points, i.e. points flattened that are not
"read" by the fingers but usually visible in the scanned image,
see Figure 2 b). It is also possible that a paper read (i.e.
touched) several times, can have some stains on it. Sometimes
the sheets are taken out of the typewriter to be read
and then reintroduced to continue typing; this may result in
some misalignments in the characters and in their separation
with the rest of the lines. Finally the pressure exerted
when the child is enthusiastically tapping the keys can create
some little holes in the Braille relief points, these holes
will appear as additional shadows in the image, see Figure
2a). As a result there are papers with different kinds of imperfections:
stains that can be misunderstood with real
Braille points, "deleted" points that can appear as non-deleted
points, double points produced by the holes in the
paper, misalignment of lines and rows, etc.
2.2OBR Technology
An OCR application is software that converts a digital
image of text, acquired by a scanner or digital camera, to a
text file that can be edited by a text editor [6] [7]. Nowadays
there are a number of commercial OCR tools, sometimes
distributed with scanners, which perform this function.
OCR avoids the need to retype printed texts. From a
technological point of view, an OCR system consists of three
phases: low level process, segmentation/detection of the
document structure and character recognition or classification.
The low level process applies techniques of image
processing to enhance digital images acquired from paper
(using contrast enhancement, filters to delete shadows, stains
and different kinds of noise etc.). The segmentation process
separates and labels the components forming the physical
structure of the document which are structured in a hierarchical
way as: paragraphs, lines, words and characters.
Finally, the recognition or classification step identifies, for
each image zone containing a character, which character it
is. The latter process compares a set of features extracted
from the image [8] with the models or patterns previously
56 UPGRADE Vol. VIII, No. 2, April 2007 © Novática