PCL and HPGL, TIFF, PDF, etc.
A General Introduction to File Formats
 
Learn more about: PCL   HPGL   TIFF   HTML-XML   PDF   JBIG2   PNG

What is PCL?

PCL is the standard print format for HP LaserJet-compatible printers.  If you are now printing to a laser printer, you are using PCL!  PCL files can be created from any Windows application by simply "printing to file" with a LaserJet-compatible printer and PCL driver set as the current Windows printer, or by redirecting a UNIX LaserJet-compatible printer queue to a file.  This is easy to do, requires no licensed software and is inherently a true representation of the document. 

Printer control language (PCL) was released in the 1980s by Hewlett-Packard as a simpler, faster and less expensive alternative to PostScript-based laser printers.  PCL retains all those advantages today.  Nothing comes for free, of course, and PCL has fewer features than PostScript or it descendant, PDF.  However, the vast majority of business documents do not require the power of PostScript.  Fewer features means simplicity, the biggest reason most workgroup printing is PCL and most printers sold today are PCL-based.  Over 70 million LaserJets can't be wrong!

PCL was created from the beginning as a simple, open language.  HP's business is printers, not proprietary page description languages.  The result is that there are many vendors in the PCL business making printers, software which enhances print jobs, viewers, and more.  This competition assures quality and cost effectiveness. 

The fact that PCL is directly printable (you can run "print filename.pcl" in DOS or "lpr filename.pcl" in UNIX and it will print on any LaserJet compatible printer) gives PCL fundamental advantages as a portable document format over non-print-ready formats like PDF or TIFF.  You can rest assured that as long as PCL-compatible printers continue to be available, your electronic document is at least as good an archival format as paper.

Learn more about archiving with PCL.
Compare PCL and PDF - How do I choose?


What is HPGL?

HPGL (Hewlett-Packard Graphics Language) is the standard print format for HP plotters, i.e., the data stream sent to HP (and compatible) plotters.  If you are now plotting to a Hewlett-Packard plotter, you are using HPGL!.  Most CAD programs output HPGL directly because they can print on HP plotters.

HPGL is a an open language vector graphics file format (as opposed to raster or bit-map), assuring optimal file size with very fast and 100% accurate rendering.  HPGL/RTL can be output by all CAD/CAM/CAE systems.   All HP printers starting with the LaserJet 3 include HPGL as an integral part of PCL support.  RTL (raster transfer language) is a raster-based specification and a subset of standalone HPGL (but not within PCL). SwiftView supports standalone HPGL, HPGL2 and monochrome RTL, and HPGL in PCL.

Learn more about the advantages of SwiftView and HPGL.
Compare HPGL and PDF - How do I choose?


How SwiftView uses PCL, HPGL, and TIFF
SwiftView supports the open, industry standard formats PCL, HPGL, and TIFF.  SwiftView also supports limited forms of the standard formats JPEG, CALS, PCX, and DCX. 

When viewing a PCL or HPGL file, SwiftView simply displays on screen what would have been printed, plotted, or imaged.  The page breaks, page numbers, margins, gridlines, headers and footers are all as you would see them when printed because the files are actually created by printing to a file.  This is "vector" style data, not a bit-mapped image, so the representation is concise and fast to render. 

SwiftView's "Intelligent Printing" insures the fastest, most accurate printing of PCL and HPGL files possible, by copying the file directly to the printer if file and printer are compatible ("direct print"), else accurately rendering to PCL for LaserJet-compatible printers ("fast print"), else using the printer's Windows print driver as a last resort.


What is TIFF?

TIFF (tagged image file format) is one of many file formats that are purely graphical, i.e., bitmap, rasterized, pixilated images.  TIFF is commonly produced by scanners, fax machines, and other imaging hardware and software.   SwiftView supports TIFF because it has long been used as an archiving and imaging format, and is quite stable, simple, and well-defined.  Contrast this with the rapid change underway in formats like PDF - which is at least an order of magnitude more complex. 

SwiftView offers several advantages over other TIFF viewers, including our trivial-to-learn user interface and fast display.

SwiftView has historically not recommended converting portable PCL documents to TIFF because of TIFF's:

  • Large file size.  TIFF files are rendered pixel-by-pixel and are often large files, often forcing use of lower-resolution or less color than the original electronic or paper document (e.g. converting to FAX-resolution bitonal).  In addition, zip compression does not reduce TIFF file sizes as much as other non-raster formats like PCL. (The recent addition of JBIG2 bitonal compression to the TIFF standard promises to largely eliminate this disadvantage.)
  • Lack of searchabilty; loss of text information.  Traditional TIFF is purely graphical; in order to search, select or index the data, the file must be further processed by OCR (optical character recognition).  OCR is well-known to be less than 100% accurate, requiring time-consuming proofreading of files to correct garbled/missing text.  (Microsoft has addressed this by extending TIFF to embed the original or OCR-generated text for Windows OS fileystem search; this features is supported in SwiftView 8.3.3.)

Compare TIFF and PDF - How do I choose?


What are HTML and XML?

HTML (HyperText Markup Language) is the publishing language of the World Wide Web, and is defined by its ubiquity - the ability to be viewed with any web browser.  HTML supports text, multimedia, and hyperlink features as well as scripting languages, style sheets, and more.  Because HTML is relatively format-free, it is best for text and graphics whose exact placement or formatting is not critical.  Unless special steps are taken, text does not appear in pages with a specific width, so changing the browser window shape or text size specifications may change the layout of text and images.  Without plug-ins, graphics are limited to simple GIF, PNG, or JPEG images, each in a separate file, which increases site management requirements. 

History & Technical Background on HTML and XML
Before HTML and the web (click here for some history), there was SGML (Standard Generalized Markup Language).  According to "document experts," SGML was the perfect solution for any real document problem.  It did not succeed because SGML is only a framework for inventing new markup languages like HTML.  No real progress was possible until a solution became available which was 1) simple enough to become a de facto standard and 2) not changed with every committee meeting.  That something was HTML.

Tim Berners-Lee and others deserve huge kudos for developing such a simple (and for the first time actually useful) markup language.  HTML and the concept of a URL are what made the web possible.  Without those, we would all still be discussing "perfect and complete document representation" instead of being part of the biggest technology and transportation revolution since the airplane.

XML is simple SGML-based markup language intended for data interchange between applications.  It is considerably less constrained than HTML, and as a result considerably harder to make work in the real world.  It is little more than a way to organize parameters and values; for it to be actually useful, all users must agree on a "data dictionary" that defines the meanings of the parameters.  It is critical to understand what XML brings to a given data sharing task to decide if the extra problems and complexity are worthwhile.

Efficiency comes from constraint. Unconstrained definitions (like SGML) are not particularly useful for real, worldwide solutions.

"XML makes it easier for two systems to exchange data with each other.  Your data is described using tags that describe what each piece of data is.  XML doesn't replace HTML, though; they're designed for different purposes.  XML is the Web's language for data interchange and HTML is the Web's language for rendering." - from an IBM XML tutorial
"The applications that will drive the acceptance of XML are those that cannot be accomplished within the limitations of HTML.  These applications can be divided into four broad categories:
  1. Applications that require the Web client to mediate between two or more heterogeneous databases. 
  2. Applications that attempt to distribute a significant proportion of the processing load from the Web server to the Web client. 
  3. Applications that require the Web client to present different views of the same data to different users. 
  4. Applications in which intelligent Web agents attempt to tailor information discovery to the needs of individual users." 
  5. - from Sun Microsystems

XML may well revolutionize such data applications but that will always come at the expense of additional effort or changes to existing systems.

Compare HTML and PCL - How do I choose?


What is PDF?
Adobe PDF (Portable Document Format) is a widely used document exchange format which is readable by anyone using Adobe's freely available Acrobat Reader.  It is distantly related to Adobe's other popular document language, PostScript.  Because PDF is rich in features to support photographic images, graphics, and color profiles.  It has started to supplant PostScript as the first choice for users who require accurate color reproduction - and are willing to wait for it, for example in the desktop publishing and color print fields.

Beginning in the late 20th century, PDF rapidly rose in popularity as a general format for electronic document exchange, primarily due to the availability of Adobe's free reader.  Many modern desktop computer systems come with some version of Adobe Acrobat Reader pre-installed, and the ability of the end user to read documents in PDF format is taken as a "given" by many distributors of electronic documents.

As PDF expands to include multimedia and other types of information, it has become necessary to define PDF subset standards.  Examples are the new PDF/A standard for archiving, and PDF/X for print exchange.  (The great thing about standards is there are so many to choose from!)

PDF/A
PDF/A is a much simpler form of PDF designed to insure long-term usability of archived documents.  It is itself divided into sub-standards, including PDF/A-1b, the most basic form, and PDF/A-1a, which adds searchable and reflowable text.  SwiftView outputs PDF/A-1b compliant files, using JBIG2 compression, plus hidden embedded searchable text, provding the most useful PDF format possible.  For more info, visit the PDF/A Center of Competence and read their whitepaper

Not all PDF is created equal: Image v.s. Vector PDF
PDF is used differently in document and imaging applications.  Scanning and imaging applications are beginning to produce a raster-only subset of PDF, commonly referred to as "image PDF". 

As PDF gains popularity, many companies have begun to output PDF from their document and drawing authoring systems, often using Adobe's Acrobat Distiller or competing PDF conversion software.  Because few documents originate in the PDF format, and because PDF is rarely used for printing, PDF files created in this manner are effectively CONVERSIONS.  ALL conversions (even conversions by Adobe Distiller) can potentially degrade document quality.  And because PDF is far from the "ideal" choice for many applications, e.g., large-format CAD drawings, multipage files with different page sizes or duplexing, or lengthy text documents with no graphics or color, the quality of converted PDF varies greatly. 

Most converters output "vector" data, i.e., discrete graphic entities.  While in many cases this may result in a smaller file size, it can cause inaccuracies because no two graphic languages ever implement exactly the same rendering model.  For example, fonts in the converted document may not be exactly the same as in the original, and PDF reader/converter/renderer support for transparency is spotty. 

The SwiftView difference:

SwiftView Pro and SwiftConvert create PDF that is NOT A CONVERSION: it is a print-perfect raster image taken from the document or drawing's print stream (PCL or HPGL).  SwiftView Pro/SwiftConvert's "true print-quality" rendering makes PDF documents that look just like the originals because they are essentially a "picture" of the original document.  This rendering technology is the same as in SwiftView, the most accurate PCL/HPGL viewer available, and is the result of over ten years of refinement and use in thousands of applications by millions of users worldwide.  In addition, SwiftView version 8.2 uses JBIG2 for bitonal PDF documents, so the file size penalty for images is quite small.

When converting PCL files, SwiftView tools also embed "hidden" searchable text in the PDF or TIFF file along with the raster image, in the same manner as OCR software, so that the PDF files are searchable in SwiftView Pro+PDF and Acrobat Reader and TIFF files are searchable using Windows file search.

SwiftView Pro/SwiftConvert's PDF export process lets you choose:

  • Resolution: Optionally view, print, or export at 600 DPI for cleaner, crisper text and images.  Or export to PDF at a lower resolution for more compact files.
  • Color: Export color PCL as color PDF.
  • Part or Whole file: Export an entire document or drawing, a range of pages, or a selected region of a page or drawing.
  • Intelligence: SwiftView lets you export searchable PDF from searchable PCL/HPGL documents, including selectable text.

Conclusion: SwiftView is an excellent choice when accurate reproduction of the original document is critical.  But don't take our word for it, learn from the experts why conversions are never perfect.

Learn more about SwiftView Pro or SwiftConvert.

Compare PDF, TIFF, and PCL - How do I choose?


What is JBIG2?
JBIG2 (named for those who created it, the Joint Bilevel Imaging Group 2) is an International Telecommunication Union format.   Image compression experts from a variety of companies (including but not limited to Siemens, IBM and Xerox) joined to develop the JBIG2 standard for compression of black and white (bitonal) scanned documents.  For practical purposes to SwiftView users, JBIG2 encoding shrinks the size of PDF images many-fold, making them 3 to 10 times smaller.   For more technical analysis of how JBIG2 achieves image compression, including discussions of bi-level images, lossless and lossy compression, visit An Introduction to JBIG2, or the JBIG2 committee home page.

JBIG2 is subject to patent rights from two patent holders, IBM and Mitsubishi.  However, both have agreed to freely license their patents to all who ask.  SwiftView has obtained full patent licensing, so you do not have to worry about patent issues when you use SwiftView Tools.  You can obtain your own JBIG2 patent licensing by contacting:

Mitsubishi Electric Corp.
IP Licensing Dept.
Tel: +81 3 3218 3465
Fax: +81 3 3218 2474
Attention: Vice President of Intellectual Property and Licensing

IBM
North Castle Drive
Armonk, New York, 10504
FAX: 914-765-4420


What is PNG?
PNG (Portable Network Graphics, pronounced "ping") is an open, extensible file format for the lossless, portable, well-compressed storage of raster (bitmap) images.  PNG was designed as a patent-free replacement for the older and simpler GIF; it is also less complex than TIFF and a suitable replacement for many uses, especially small images.  PNG supports indexed-color, grayscale, and truecolor images, plus an optional alpha channel for transparency.  PNG supports up to 48-bit truecolor or 16-bit grayscale.  Saving, restoring and re-saving an image will not degrade its quality, unlike standard JPEG.   And unlike TIFF, the PNG specification does not let implementors choose what features they'll support, so a PNG image saved in one application is readable in any other PNG-supporting application.  PNG files nearly always use the file extension PNG or png and are assigned the MIME media type image/png.

Modern browsers support PNG: Microsoft Internet Explorer for Mac OS, Windows and Unix, Netscape Navigator/Mozilla/Firefox/etc., and others.  Many viewers and content creation tools for PNG are available on many platforms.

Learn more about PNG at the Official PNG Website.

Learn more about creating PNG with SwiftView Pro or SwiftConvert.



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