Braille Embossing

Background

A braille embosser is a dot-matrix printer of sorts. However, instead of spreading ink, it mechanically distorts the base material. The result is a set of dots that rise out of an otherwise flat surface. These dots are generally used to represent braille patterns, but they can also be used for low-resolution (~0.09" per pixel) image data.

Many units require continuous form (specifically, pin-feed) paper. Standard 20# paper will serve for light-duty or temporary use, but braille paper should be used for archival or intensive use cases.

Desktop embossers have been around for quite a while, so used low-end units (e.g., Braille Blazer) are readily available and can be purchased for about $100. The default interface on the Blazer is IEEE-1284 (aka "Centronics printer"), which many modern computers do not support. Fortunately, USB adaptors and Ethernet-based "print servers" are also cheaply available. For more information, see my Hardware page.

File Formats

In computer graphics, a raster graphics image is a dot matrix data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium. Raster images are stored in image files with varying formats.

-- Raster graphics (WP)

Although various image processing tools perform format conversion, no common tools target braille embossers. So, we need to pick a commonly available and simple format to use as an intermediate representation. Netpbm's Portable Bitmap format (PBM) is a good candidate: The PBM Plain variant is text-based, uncompressed, and stores one bit per pixel.

My PBM2BB (PBM to Braille Blazer) script takes advantage of this. It reads a PBM input file (or stream), converting it to Braille ASCII. The resulting raster image is as long as needed and up to 90 pixels (i.e., dots) wide.

Breakout Pages

To be continued...


This wiki page is maintained by Rich Morin, an independent consultant specializing in software design, development, and documentation. Please feel free to email comments, inquiries, suggestions, etc!

Topic revision: r72 - 19 Feb 2016, RichMorin
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