Things to look for

1. Rectangles. The color of the rectangles should be consistent and continuous. Look out for lines or patches of other colors of gray. In particular, check that the transitions from a darker to a lighter rectangle, there should not be any lighter or darker areas close to the border. For some printers, the lighter rectangle will be estra light near the border area.

   Note that this effect will also be the result of an optical illusion, which will make each rectangle look lighter close to its darker neighbor, and darker close to its lighter neighbor. However, the optical illusion will make the rectangle look like it have a continuous change of gray. If is change abruptly close to the neighbors, it is an indication of a defect.

2. Corners. In each corner, there is a quarter of a gray circle, and two black sectors. They all have center at the corner of the a4 sheet, and you can use them to detect how large is the non-printable margins of the printer.

3. Globe. The globe should have a continuous change of tone from white at the center to black at the perimeter. There should be no ripple-effect from the center.

4. Information. The textual information will give you some system values from the printer. However, due to the fact that PostScript define very few such values, they are not so interesting. Most printers have additional system values, which are generally system specific.

   The values defined in the testpage is Product, which defines the name of the printer model. The Interpreter version is a system specific, and generally defines the version of the software of the printer -- it is not the same as the language level. The Revision is the revision number within that interpreter vesion. The Serial number is a the serial number of the printers postscript processor, which is not necessarily related to the serial number of the printer itself. Hopefully, the serial number is different from printer to printer, so you can identify different printers by it. The Language level is the supported PostScript language level of the printer. The User time and Real time defines the CPU-time spent and eleapse time since the printer was booted; but it may not really give any interesting numbers.

5. Pyramid. It is actually drawn in colors, but if your printer is a black-and-white printer, you will see it in gray. It should have a continuous change of gray, but some printers have color-crrection schemes that enhances some ranges of colors, and for these printers, there may show up clearly defined abrupt changes in the tones of gray. Preferably, such corrections should not be noticable, so it's a bad sign. Note that the upper right side of the triangle is supposed to be kind of step-like.

6. Ovals. The ovals are drawn as a number of ovals on top of each other, so that the lines that appear are the result of background between broad lines. In the left ovals, there is black background between broad white lines; while in the right ovals, there is white background between broad black lines. In all cases, the lines should be uninterrupted and smooth; and the lines should never appear "dotty".

7. Quadrants. The four quadrants are drawn by a number of radiant lines from a center to the perimeter of a circle. The difference between the four quadrants are only the thickness of the lines. The thickness of the lines changes counter-clockwise from the upper right (having the thickest lines) to the lower right (having the thinest lines). For all printers, the lines brak down into a black blob at the center, however, the closer to the center you can follow the lines, the better. On a good printer, you should be able to se a difference between all the four quadrant, and there should be as little patterns of interference as possible.

8. Cross. The lines in the cross will break down into a black broad line near the two axis. On a good printer, you will see a regular grid all the way in to the black area. In addition, there should be a consistent thin white line along the axis of the cross (except in the center of the cross). The figure should be symetric.