HP Printer Languages

In order to print, the printer (or HP plotter) uses a variety of instructions via a control language created by HP. HP GL stands for “Hewlett Packard Graphics Language” and it is a standard language for many of their large format printers. The original HP GL language was then updated to control line width as well as other improvements such as a binary file format which enabled smaller files, shorter transfer times and a reduction in minimal resolution. This was called HP GL/2.

This printer control language is not the only one that has been created to work with printers – there is also, for example, the PCL and HP RTL languages.  In short, the control language used depends upon the type of object that you want to print.  The languages shown on HP DesignJet specification sheets are detailed below:

Language

Definition

HP-GL/2 HP-GL/2 instructs the printer primarily on Vector objects.  Vector objects are composed of straight lines or combinations of straight lines such as squares, rectangles and other polygons.  They can also be used to create curves, arcs, circles, ellipses as well as more complex curves. The HP-GL/2 instructions also fill print areas with patterns of various types and can create character labels (text) that appear on drawings.  It also defines the logical page, picture frame or window which is that part of the physical page where the objects are placed.  For various image types such as technical drawings and business graphics it’s advantageous to use vector graphics instead of raster graphics (see description of HP-RTL below) since it transfers the large objects faster and requires smaller disk storage space.  HP-GL/2 can also be used for images that involve a large amount of data transfer or for drawings already in HP-GL/2 format. The printer can use HP-GL/2 in conjunction with either PCL or HP RTL to create different parts of a single drawing or picture.
HP PCL3 GUI PCL3 GUI instructs the printer primarily on Character objects.  PCL is also known as Printer Command Language and is a page description language which was first introduced in 1984. There have been many revisions. The PCL 3GUI is used in HP DesignJets and it uses a compressed raster format that is not compatible with standard PCL 3. Character objects give you access to the wide range of character fonts, and it also defines the graphics limits.  In order to print with HP-GL/2 you would need to leave the PCL print language mode and enter the HP-GL/2 mode.  Switching between modes is easily attained using only a few commands or software applications.
HP-RTL HP-RTL instructs the printer primarily on Image objects.  RTL is also known as Hewlett Packard’s Raster Transfer Language.  Image objects comprise things such as scanned photographs.  It is also used to shade areas and is a subset of the PCL Printer Language. Most modern DesignJets are raster devices so they need a raster based language and this language has been designed to mix with the HP-GL/2 language.  Generally raster graphics can be used for small, complex images or those images that cannot be accomplished with HP-GL/2 (such as scanned photographs).
CALS G4 CALS G4 is a Raster file format (Group 4) and is a standard for the interchange of graphics data for electronic publishing and defines how a raster image data (bitmap) should be encoded and compressed. It was developed by the US Department of Defence (the Computer Aided Acquisition and Logistics Support (CALS) office) and is especially used in the area of technical graphics and image processing applications.
JPEG JPEG is used for compression of digital photography which can be adjusted.  It allows a trade-off between storage size and image quality and can achieve a 10:1 compression with little perceptible loss in image quality.  It is an acronym for the Joint Photographic Experts Group, which first created the standard in 1992.
Adobe PostScript Adobe PostScript is a worldwide standard used for printing and imaging, which enables visually rich documents to be printed easily and reliably. This scalable printing technology is licensed to OEMs (original equipment manufacturers) and allows HP to offer high performance printing systems and print workflow solutions, including accurate colour conversions together with high quality and performance on their range of PostScript (PS) DesignJets. In practical terms the PostScript option allows you to easily create portable document format (PDF) direct from scanned documents and also speeds up the printing process by giving you the ability to queue and print PDF files without ever opening the file For example, you could select and send 10 x PDF files to the print and have them print without ever viewing them. Although some DesignJet models offer an option to upgrade to PostScript, it is cheaper to purchase the PostScript option at the outset.
Adobe PDF Portable Document Format (PDF) was invented by Adobe Systems and is now a standard for electronic document exchange, which is maintained by the International Organization for Standardization (ISO) and trusted by businesses and government agencies around the world. PDF’s allow you to convert many different types of documents including forms, graphics, web pages and word documents. Once converted they look just like they would if printed. However, while viewing the document on-screen the PDF files include logic, clickable buttons, links, video, audio, form fields, electronic signing and word searching to provide ultimate ease for the reader and a smooth exchange for the sender/creator. These documents can be shared with virtually anyone (using Adobe Reader software – which can be downloaded for free on the internet) and can also be viewed on most platforms including Windows, Mac OS, Android, iOS for iPhone and iPad.
TIFF TIFF – or Tag Image File Format – is an image file format which is highly versatile due to its extensible nature which allows storage of multiple bitmap images of any pixel depth, that make it ideal for most storage needs.  It’s one of the most popular and flexible raster file formats. It can be used in any operating environment and was first released in 1986.  It supports uncompressed RGB colour images, stores palette colour images and provides added support for CMYK colour images and the JPEG compression method.