Paste: Comparison of PostScript and PCL in Printer Language

PostScript Language

Postscript is a device-independent printer language, that is, when defining an image, you do not need to consider the characteristics of the output device (such as the resolution and size of the printer ), in addition, it implements the same processing process for text and graphics, which brings great flexibility to the processing of fonts. Due to the device-independent feature of postscript, postscript uses the printer description (postscript printer description) to describe the output to a specific output device, such as the resolution, paper size, and input tray) file to implement different printer features. The PPD file mainly provides the following printer-related information: default/Maximum resolution, whether halftone monitoring, user-defined monitoring information, page size definition, and printable area, default font (usually courier), whether dual-sided printing is supported, and so on. Each different postscript printer has a dedicated PPD file. Various types of ppdfiles are stored on the Adobe Company website http //: www.adobe.com. Various applications use the PS driver to convert their data into the postscript format. According to the working principle of the printing engine, the printer can only accept the bitmap format. When the printer controller converts postscript to the bitmap format, the general printing controller is hard to perform due to the complexity of postscript, raster image processor is usually used by printers to complete this conversion process.

Since the use of PostScript printers has high requirements on print controllers, and postscript is a registered product of Adobe, printer manufacturers must pay adobe for the use of PostScript Language in their products, just like the operating system cost that a PC vendor pays for Microsoft, the cost of using a postscript printer is higher than that of a printer using other languages and control methods. Therefore, some postscript simulations have also appeared, such as the postscript simulation used in some HP Laser printers, which can be fully compatible with Adobe's postscript, you do not have to pay for Adobe.

PCL language

It is Adobe's billing method for the PostScript Language that provides development space for HP's printer command language (printer control language) language, the PCL language is a printer Page Description Language launched by HP in 1970s for its laser printer products. HP's market strategy is completely different from Adobe's. Other vendors can freely imitate or use the PCL language in their printer products. It is the openness of the PCL language that reduces the cost of printer products using the PCL language, so that the popularity of the printer products is much higher than that of the PostScript Language.

The PCL language was originally designed for dot matrix printers. pcl3 is the first widely used version, but it only supports some simple print tasks. Although pcl4 can only be used in Personal printers, it adds support for graphic printing. However, since the interpretation work is relatively simple, pcl4 has much lower requirements on the Print Controller than pcl5 and pcl6 in the later stages.

Pcl5 was designed by HP for its laser printer LaserJet III. It provides features similar to postscript languages and began to support vector font and vector graphics descriptions, WYSIWYG (what you see is what you get, WYSIWYG) is implemented, and various compression technologies are also used in pcl5 to reduce the data volume and speed up data transmission. Pcl5e starts to support two-way data communication so that the printer can send the printer status information to the computer. Pcl5c supports color printing.

In 1996, HP released pcl6, which is more flexible. It is a target-oriented control language that greatly accelerates the processing of Multi-graphic files and achieves better WYSIWYG, therefore, you can better process web pages.

Comparison between the two languages

PC world has tested a variety of black and white and color laser printers using the PCL and postscript languages. We found that the printer using the PCL language has obvious speed advantages in processing documents in text or some common office application software. In these applications, there is no difference in print quality from printers using postscript languages. Printers using PostScript Language are slower to print in common office applications, however, it has a fixed speed advantage when processing PDF files or printing large image files under photoshop or other software, at the same time, it has advantages over the PCL language in terms of image performance accuracy, Color Performance accuracy, and some font performance accuracy. In addition, the postscript language can be used on the PC platform, it can also be used on the Apple platform.

From the above comparison, we can see that the PCL language is suitable for some common business office applications, while the PostScript Language is more suitable for professional applications with high requirements on graphics and color accuracy. This is also an important reason why many printer products provide drivers of both the PCL and postscript versions.