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CUPS is a standards-based, open-source printing system used by Apple's Mac OS® and other UNIX®-like operating systems, especially also Linux. CUPS uses the Internet Printing Protocol ("IPP") and provides System V and Berkeley command-line interfaces, a web interface, and a C API to manage printers and print jobs.
This package contains backends, filters, and auxiliary files for Braille embosser support, currently only as a classic CUPS printer driver package. A conversion to a Printer Application is in the works and will get committed here soon.
For compiling and using this package see INSTALL file.
Report bugs to
https://github.com/OpenPrinting/braille-printer-app/issues
See the "COPYING", "LICENCE", and "NOTICE" files for legal information. The license is the same as for CUPS, for a maximum of compatibility.
- Converting Braille embosser support into a printer application - GSoC 2022 project by Chandresh Soni
- All free drivers in a PPD-less world - OR - All free drivers in Snaps
- Current activity on Printer Applications
Most of this is still valid for the current cups-filters.
cups-filters also provides filters and drivers for braille embossers. It supports:
- Text on all kinds of embossers with generic support
- Text and graphics on the Index V3 embossers and above.
This is configured in CUPS just like any printer. Options can then be configured in the standard printer panel, or passed as -o options to the lp command.
Text can be embossed either with no translation on the computer side (the embosser will translate), or with translation on the computer side (thanks to liblouis). It is a matter of running
lp file.txt
or even
lp file.html
lp file.odt
lp file.doc
lp file.rtf
lp file.docx
lp file.pdf
Important: it is really preferrable to directly print the document files themselves, and not a pdf output, or printing from the application (which would first convert to pdf). That way, the braille conversion will have the proper document structure (paragraphs, titles, footnotes, etc.) to produce good quality.
Vector images can be embossed by converting them to braille dots.
This needs the inkscape package installed. Various input formats are then supported: .svg, .fig, .wmf, .emf, .cgm, .cmx
The conversion assumes that the input is black-on-white. If it is white-on-black, the -o Negate option can be used.
This image support is preferred over the generic image support described below, which has to reconstruct lines to be embossed.
Images can be embossed by converting them to braille dots.
The orientation of the image can be controlled. By default it will be rotate to fit the image orientation, i.e. it will be rotate by 90 degree if it is wider than high and the paper is higher than wide, or if vice-versa. Other rotation modes are provided.
By default, the image will be resized to fit the size of the paper. Disabling the resize (fitplot set to No) will crop the image to the paper size. This is useful for instance when a carefully-drawn image was designed especially for embossing, and thus its pixels should exactly match with braille dots. In such case, edge detection should very probably be disabled too.
The image can be processed for edge detection. When no processing is done (edge detection is configured to "None"), the dark pixels are embossed if the Negate option is off, or the light pixels are embossed if the Negate option is on. When edge processing is done, only the edges of the images will be embossed. The Basic and the Canny algorithms bring differing results. The Basic algorithm can be tuned thanks to the edge factor only. The Canny algorithm can also be tuned: increasing the Upper value will reduce the amount of detected edges (and vice-versa), increasing the Lower value will reduce the lengths of the detected edges (and vice-versa). The Radius and Sigma parameter control the blurring performed before edge detection, to improve the result; the Radius parameter controls how large blurring should be performed, setting it to zero requests autodetection; the Sigma parameter determines how strongly blurring should be performed.
A lot of images formats are support, so one can just run
lp file.png
lp file.gif
lp file.jpg
...
Here are complete examples for controlling the processing (all options can be omitted, the default values are shown here):
Emboss the image without edge detection, as black on white or white on black:
lp -o "Edge=None" file.png
lp -o "Edge=None Negate" file.png
Emboss the image with edge detection, the default tuning parameters are set here:
lp -o "Edge=Edge EdgeFactor=1" file.png
lp -o "Edge=Canny CannyRadius=0 CannySigma=1 CannyLower=10 CannyUpper=30" file.png
Emboss the image as it is, without any resize or edge detection, as black on white or white on black:
lp -o "nofitplot Edge=None" file.png
lp -o "nofitplot Edge=None Negate" file.png
It should be possible to make all embossers use the generic driver. For this to work, one has to:
- configure the embosser itself so that it uses an MIT/NABCC/BRF braille table
- add in CUPS a printer with the "Generic" manufacturer and "Braille embosser" model
- configure CUPS options according to the embosser settings, so that CUPS knows the page size, braille spacing, etc.
The generic driver can emboss text, as well as images, but images will probably be distorted by the Braille interline spacing.
Supported models:
- Basic-S V3/4
- Basic-D V3/4
- Everest-D V3/4
- 4-Waves PRO V3
- 4X4 PRO V3
- Braille Box V4
Index V3 embosser support has been well tested. It supports both text and graphics mode. Embossers with firmware 10.30 and above can be easily configured from CUPS (paper dimension, braille spacing, etc.).
Index V4 embosser support has not been tested, but is very close to V3 support, so it is probably working fine already. Feedback would be very welcome.
To connect an Index embosser through Ethernet, gather its IP adress, select the "AppSocket/HP JetDirect" network printer protocol, and set socket://the.embosser.IP.address:9100 as Connection URL.
The density of dots for images can easily be chosen from the command line, for instance:
lp -o "GraphicDotDistance=160" file.png
to select 1.6mm dots spacing
Troubleshooting: if your embosser starts every document with spurious "TM0,BM0,IM0,OM0" or "TM0,BI0", your embosser is most probably still using an old 10.20 firmware. Please either reflash the embosser with a firmware version 10.30 or above, or select the 10.20 firmware version in the "index" panel of the cups printer options.
The output can be finely tuned from the standard printing panel, or from the command-line, the following example selects translation tables for French and Greek, with 2.5mm dot spacing and 5mm line spacing. All options can be omitted, the default values are shown here.
lp -o "LibLouis=fr-fr-g1 LibLouis2=gr-gr-g1 TextDotDistance=250 LineSpacing=500" file.txt
One may want to check and modify the .brf or .ubrl output before sending it to the embosser. This can be achieved by first generating the .brf file:
/usr/sbin/cupsfilter -m application/vnd.cups-brf -p /etc/cups/ppd/yourprinter.ppd yourdocument.txt > ~/test.brf
One can choose a ppd file and additionally pass -o options to control the generated output. One can then modify the .brf file with a text editor. One can then emboss it:
lp -o document-format=application/vnd.cups-brf ~/test.brf
The same can be achieved for images:
/usr/sbin/cupsfilter -m image/vnd.cups-ubrl -p /etc/cups/ppd/yourprinter.ppd yourimage.png > ~/test.ubrl
lp -o document-format=image/vnd.cups-ubrl ~/test.ubrl
One can generate BRF files by adding a virtual BRF printer.
When creating it in the cups interface, choose the CUPS-BRF local printer, select the Generic maker, and choose the Generic Braille embosser model.
Printing to the resulting printer will generate a .brf file in a BRF subdirectory of the home directory.
One can generate Unicode braille files, not useful for embossing, but which can be easily looked at by sighted people to check for the output.
In the cups interface, create a printer with the CUPS-BRF local printer, the Generic maker, and choose the Generic UBRL generator model.
Printing to the resulting printer will generate a .brf file in a BRF subdirectory of the home directory.
The file driver/index/ubrlto4dot.c is used to generate the translation table in driver/index/imageubrltoindexv[34]. It is included as "source code" for these two files, even if actually running the generation in the Makefile is more tedious than really useful.
- Test whether one wants to negate, e.g. to emboss as few dots as possible
- textubrltoindex when liblouis tools will be able to emit 8dot braille
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