What is the difference between PCL and Postscript drivers?

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printers Q: I notice that printers with PostScript capability cost more than otherwise identical ones that don't (ones that have only HP PCL capability). Are they worth the extra money?

A: Most graphics professionals insist that PostScript ability is essential for them and desirable for most users. We'll accept to an extent the first claim, but we're skeptical about the second. One difference between PCL and PostScript is that with PostScript, you gain extra control of certain kinds of output. An obvious difference is that the PCL printer can't print PostScript graphics (EPS files). (True, you can get software to convert an EPS file to, say, TIFF. Once converted, however, it may not resize as well or may pick up a jagged edge on curved lines.)

Not as obvious at first, but more important in the end to professionals, is control over halftoning. (Halftoning is the process of splitting a photograph into small, evenly spaced dots that blur together when printed.) PostScript has half-toning built in, so you can specify technical printer instructions, such as "print a 600dpi graphic at 70 lines per inch at a 45-degree angle," something that's not easily done with a PCL printer.

Another equally important point: When you output first on, say, a 300dpi PCL printer as a draft and than later send it to a service bureau for high-resolution 1200dpi output, the service bureau is likely to have a PostScript-driven output device. If you've proofed on PCL, there may be slight changes in output when you "translate" it to PostScript for the service bureau—slight changes that could screw up an expensive job. If your original/ proof/draft output was also in PostScript, you could be more confident that things will stay stable as you move between other output devices.

For most users, these things are somewhat esoteric. And if your laser printout is your final product, PCL and PostScript should be about equal. In fact, we've often tried to get someone to show us an example of the same few pages of diverse graphics printed from the same software, in one case using the PostScript printer drivers and in the other using the PCL printer drivers. We wanted to see if a PostScript printout had significantly better-looking output. Someone has yet to meet that challenge. Keep in mind that less than 5% of Windows users have PostScript printers. Fifty million PCL printer users can't be wrong.

If you do need to have the printout reproduced (photocopied, make printing plates, etc.), PostScript's control of halftones and whatnot is important. Therefore, with PostScript you pay up-front for ease of use, control, and consistency as you move between different output devices and not necessarily for better output at your printer.