LIDIL Language Printers > Language > LIDIL | Navigation Icons Guide
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Lightweight Imaging Device Interface Language (LIDIL)
LIDIL or LDL is a Hewlett Packard print protocol for sending raster graphics to a printer that uses "Host Based" printing.
In conventional printing the computer sends the printer a series of text codes with embedded instructions on the font selection, size, and colour of the text, together with any line drawing the page might hold as vectors and any pictures as bitmaps. Print languages such as PCL, Epson Esc/P and PostScript have evolved over the years and are intended to make quite efficient use of computer memory and processing power and computer to printer communication capabilities.
Using a print language also frees the design of printers from dependency on any one operating system. Printers will have at least basic functionality used with any variety of Windows or its predecessor DOS, with any version of Unix or Linux, and with other operating systems like BeOS.
Reconstructing the page image from the print language does require the printer to have a moderately powerful processor (typically between 40 and 400MHz) and some memory (typically above 64Mb). These resources are no longer costly but they once were. Even now the printer industry is very competitive so manufacturers take any opportunity they can to cut unnecessary costs of hardware and development out of the budget, especially if the printer is aimed at home use where buyers are very sensitive to purchase price.
Rather than making up the printed page itself a host-based printer is sent the bitmap it is to print from the user's computer. The driver interprets the page to a this bitmap form, instead of an intermediate print language. The bitmap translates more or less directly to pixels on the page, which together with a few commands to start the print engine, select trays and eject the printed sheet deliver the page to the user. The printer is not entirely dumb but it only needs enough memory and processing power to do rudimentary things.
Some host based printers can print basic ASCII text. LIDIL purely handles raster graphics, in itself the printer can't even print text at all, it just accepts the bitmap sent by the computer and prints that.
Many of HP's Deskjet, OfficeJet and PSC printers use LIDIL. At the time of writing there is a list at http://hplipopensource.com/hplip-web/sleek.html
Some LaserJet printers also use LIDIL although the specification often just says "host based".
Individual Windows XP and Vista users just install the print driver as normal, plug the printer in and have no reason to know that the printer is doing anything different. Linux can use the "hpijs" driver under CUPS. The HPLIP print subsystem give full support to LIDIL printers.
Printers that support LIDIL advertise it as LDL in the CMD field of a device ID string. The host system can detect that and use an appropriate driver.
In principle it is possible to use LIDIL across a network. The potential disadvantage is that the data transfers will be larger than usual. Host computers sending to a network printer also need to know how to format the data, which won't be true of operating systems that aren't commonplace and expected to use cheap little printers.
LIDIL is a successor to HP's PPA protocol used on HP Deskjet Series Printers 710c, 712c, 720c, 820c, 1000c, 3300c, and 3400c.
Similar methods are used in
GDI Printers printers with Windows Graphical Device Interface commands driver, or so called Windows printers
and in Canon CAPT
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© Graham Huskinson 2010
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