Print quality test target: developed to test postscript printers
Werner K. Sobotka · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1992
1.1 PremisesIt is an advantage ofopen publishing systems thatitis possible for the user to put togetherparts ofdifferent suppliers to a completesystem. Standardized interfaces provide the links between the different parts of a system.One of the key technologies for output is PostScript, the well-known page description language, developed by Adobe systems.It has become a de-facto standard for computer publishing applications.The main advantage of PostScript is its device independence: Any document can be printed on any PostScript output device inany available resolution.The idea of device independence, however, leads to some problems: If there are problems concerning output quality, it is verydifficult to detect the source ofthese problems. Without additional help it is often impossible to find out which part ofthe system(scanner, software, output engine, the developing process) causes the problem.1.2 ObjectivesUntil now, Computer Publishing systems lacked control systems like those used for offset printing.The objectives of the VFG-GLV-PostScript-targets were to develop test targets, which enable any user to evaluate and maintainthe quality of any output device (printer or imagesetter). These test targets should be supplier independent.1.3 Developing the test targetsDeveloping the test targets started early in 1990 at the institute for Graphic arts in Vienna (Graphische Lehr- und Versuchsanstait,GLV). The first protoypes were used at CeBIT 1990 for an imagesetter comparison. In 199 1 the concept was refined, giving twotest targets: TheVFG-PTFandtheVFG-PQF. After field testing in 199 1 they areavailablearoundthe world since September1991.The test targets were developed using direct PostScript programming. Main parameters ofthe output device are interrogated andare used to build test targets suited for a specific device resolution on the fly. Some test targets are device dependent and showoutput quality for a specific device at a specific resolution. This is the advantage of a test target, created by aprogram. It allowsto deal with specific devices.The test targets ar therefore suited to test imagesetters at high resolutions as well as low-res laserprinters.1.4 VFG-PTF: Quality evaluationThe VFG-PTF test target helps evaluate the quality ofa PostScript printer or imagesetter. Its size of 20x20 cm allows for a largequantity oftest targets. The test target checks resolution, screen angles, density, and the quality ofmechanical and optical system.The evalutation of the test targets will be done visually or using a densitometer.1.5 VFG-PQF: Quality maintenanceThe VFG-PQF testtarget is used forjob quality control. It is pasted into a PageMaker-, Ventura Publisher- or XPress-job and willbe sent to the printer with the job. This allows quality control for every page processed.