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(19 Feb 2016,
<noautolink> ---+!! Braille Embossing %TOC% ---++ Background A [[%WP_Be%][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 [[%WP_CS%][continuous form]] (specifically, pin-feed) paper. Standard 20# paper will serve for light-duty or temporary use, but [[%BP%][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., [[%BB_TPE%][Braille Blazer]]) are readily available and can be purchased for about $100. The default interface on the Blazer is [[%WP_1284%][IEEE-1284]] (aka "Centronics printer"), which many modern computers do not support. Fortunately, [[%WP_USB%][USB]] adaptors and [[%WP_En%][Ethernet]]-based "print servers" are also cheaply available. For more information, see my [[%HW%/WebHome][Hardware]] page. ---++ File Formats <blockquote> 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. -- [[%WP_RG%][Raster graphics]] (WP) </blockquote> Although various [[IP][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. [[%WP_Netpbm%][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 [[%WP_BA%][Braille ASCII]]. The resulting raster image is as long as needed and up to 90 pixels (i.e., dots) wide. ---++ Breakout Pages * [[IP][Image Processing]] * [[PBM2BB]] PBM to Braille Blazer filter, in Ruby To be continued... <!-- * Set BB_TPE_1 = http://www.freedomscientific.com/Content/Documents/Manuals/Legacy * Set BB_TPE = %BB_TPE_1%/BrailleBlazerDocs/440102-001BrailleBlazer.pdf * Set HW = Projects/Access/Utiles/HW * Set BP = http://braillepaper.com * Set WP_1284 = %WP%/IEEE_1284 * Set WP_BA = %WP%/Braille_ASCII * Set WP_Be = %WP%/Braille_embosser * Set WP_CS = %WP%/Continuous_stationery * Set WP_En = %WP%/Ethernet * Set WP_Netpbm = %WP%/Netpbm * Set WP_RG = %WP%/Raster_graphics * Set WP_USB = %WP%/USB --> %ZB%
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Topic revision: r72 - 19 Feb 2016,
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