2004 Conference Proceedings

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EMBOSSING BRAILLE AND TACTILE GRAPHICS USING WINBRAILLE

Presenters
Mats Blomqvist
Lulea University of Technology
S-971 87 LULEA, SWEDEN
Email: Mats.Blomqvist@sm.luth.se

ABSTRACT

WinBraille was developed as a Braille editor for embossing Braille on Index Braille embossers. Version 4 is able to edit and emboss tactile graphics mixed with Braille on the same page. A new format is described with a resolution of 0.5 mm to hold both the image and the embedded Braille text. WinBraille version 4 also contains a new image editor to edit graphics in this new format.

Keywords: Braille, Tactile graphics, WinBraille, Bitmap.

INTRODUCTION

This paper will focus on using WinBraille to emboss tactile graphics. Braille symbols and tactile graphics are embossed with the same type of bulging dots, but usually with different resolutions. The distance between dots in a Braille cell is 2.5 mm. The horizontal distance between dots in adjacent cells is 3.5 mm, and the vertical distance is 5 mm. Distance between dots in embossed graphics is often 2.0 mm, but 2.5-mm resolution exists as well. Denser than 1.6 mm is not used and will only lead to a perforated paper, since the dot diameter is about 1.6 mm.

INTEGRATING BRAILLE AND GRAPHICS

To be able to emboss tactile graphics with integrated Braille text, we have defined a higher graphical dot resolution of 0.5 mm, but with the restriction that two adjacent dots are not closer than 2.0 mm. A matrix with the resolution 0.5 mm can thus contain both 2.0 mm graphics, as well as Braille cells with dot distances 2.5 mm, 3.5 mm, and 5 mm.

STANDARD WINDOWS BITMAP FORMAT

WinBraille's standard format stores documents in Microsoft Word's "doc" format. To be able to show tactile graphics in the document, and also edit the document with Microsoft Word, we decided to store graphics in Windows native bitmap format. We use a resolution of 10000 pixels per meter, thus the Braille dot (1.6 mm) is painted as a circle with a diameter of 16 pixels. The high resolution is chosen because we wanted to make the painted dot as smooth as possible.

THE IMAGE EDITOR

We have also constructed an editor so images can be edited in the new format. Images in the source document can be converted to Braille with the editor and automatically pasted into the translated document. The editor translates color images according to specified criteria, as for example gray conversion parameters and black and white threshold. Images are painted with black dots and Braille text with dark gray dots. This makes it possible to distinguish between the image and the text, even though all is stored as a Windows bitmap. The image dots lay on a 2 mm grid, while the Braille dots lay in a grid defined by the 2.5 mm distance between dots inside a Braille cell and 3.5 mm distance between cells.

IMAGE CONVERSION

The image editor has several conversion options. The main purpose is, basically, to convert color, gray scale, or black-and-white images to a tactile image with bulging dots. Parameters involved in the conversion process are, among others, black-and-white threshold and the color-to-gray conversion features hue, saturation and intensity. The parameters can be adjusted in prior to the image conversion. It is also possible to draw on the image, either directly on the color image before conversion, or in the converted image. Text can be embedded, both as Braille and as outlined graphics.

Images can be resized. A color image is normally quite small, but has a rather high resolution. Images are often enlarged due to the poorer resolution in the tactile image. Images can be clipped. Tactile images produced with some programs cover a whole page, even though the interesting graphics only cover a fraction of the image. Selecting the interesting part of the image can reduce the size considerable.

EMBOSSER

The embosser must be able to emboss with the high 0.5-mm resolution to emboss images with embedded text in the new format. Index embossers version III with the latest firmware can emboss with the necessary resolution.

REFERENCE

The latest version of WinBraille and the image editor can be found at Index home page http://www.indexbraille.com


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