What Can Affect the Nature and Composition of PCL Print Streams

Posted on | November 15, 2011 | No Comments

There are many variables that can affect the nature and composition of today’s PCL print streams. Once a PCL transformation process is up and running, please be aware of some of the many pitfalls that can break them.

The PCL generated from different HP printer drivers can vary in the following ways:

  • There are HP printers that do not generate PCL at all.  They are host-based/GDI printers.
  • There are HP printers that are new host-based and use a flawed, third party PCL5 interpreter.
  • There are HP printers that only support stripped-down versions of all raster PCL XL (PCL6).
  • There are HP printers that only support PCL XL with JetReady compression (HP will not provide the tech. spec. – we had to reverse engineer it)
  • There are HP printers that support both PCL XL and PCL5e – so which driver are they using?
  • There are 50+ HP inkjet printers that print undocumented variations of PCL3GUI.
  • PCL XL is extensible by the printer manufacturer.  So, there are new functions with every new release.
  • PCL5e is not supposed to be extensible, but Lexmark and other vendors add their own proprietary commands and compression methods.
  • The new HP Universal Printer Driver on WIN7/W2K8 is buggy even when printing.
  • There are print driver options that affect the way the PCL is output:
    • Graphics Mode – Auto, Raster, vector/HPGL2, el al.
    • TrueType Fonts – as graphics, download as bitmap, download as outline
    • Font Substitutions – remap Arial to XYZ font
    • Print Processor and data type (Raw, EMF, ?)
    • Color Mgmt – Auto, manual, many proprietary color profile
    • Driver added overlays, fonts or watermarks
  • Printer manufacturers have drivers that they provide to Windows and different drivers that come with their printers for the same printer model.  They generate different PCL.
  • Different releases of printer drivers generate different PCL.
  • Upgrading Windows can update the TrueType fonts that Microsoft supplies.  If they tweak a character, it can affect our OCR process to extract text.
  • Upgrading to a new version of Windows can mean having to use a driver from a different third party printer driver vendor.
  • Printer driver output may be captured by third party tools to insert or find/replace PCL on-the-fly.
  • Not all HP printers have the same resident font selections forcing font substitutions.

PCL generated from the same application can be affected in the following ways:

  • Different selection of fonts, point sizes, style, stroke weight, justification, kerning, etc.
  • Different margin settings.
  • The order, in which the columns are originally added, then deleted and inserted – changes the order in which the text is those columns is applied in the PCL.
  • Footers in Word can cause a full page graphic overlay.
  • A document with very dense and tightly-packed text can cause the printer driver (depending on the graphics mode and other settings) to arbitrarily rasterize certain portions of what was a text string.

Remember that PCL transformation is at the mercy of everything “up-stream” from it!

PageTech

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