The smallest gap visible is limited by the smallest dot of ink the printer can produce, making the Siemens star a useful tool for comparing two printers' resolutions ( DPI). When printed or displayed on a device with limited resolution, however, the spokes touch at some distance from the center. In concept, the spokes only meet at the exact center of the star – the spokes, and the gaps between them, become narrower the closer to the center one looks, but they never touch except at the center. It consists of a pattern of bright 'spokes' on a dark background that radiate from a common center and become wider as they get further from it.

There’s a fair amount of aliasing towards the center, but that should all be a blur in actual use.A Siemens star, or spoke target, is a device used to test the resolution of optical instruments, printers, and displays. Gray Gamma 2.2 is as good as anything.Īnd here’s a really big file (12000×12000 pixels, 200 spokes), for those making a really big target.

Since every pixel in the files is either pure black or pure white, it doesn’t matter what grayscale profile you assign. When you open them in Photoshop, you’ll see something like this: If you want bigger targets, scale them using bilinear interpolation. If you want to print on smaller paper, crop the targets, but print at 360 or 300 ppi. To download a file, right-click on the link below, then choose “Save as…”įor optimal results, don’t scale the targets send them to your printer driver at 360 ppi in the case of the Epson files, or 300 ppi for the Canon ones. There are three stars for Epson printers, which want 360 ppi input images, and three for Canon printers, which take 300 pi images. All are sized for 16-inch (410 mm) stars. Below are links to six printable targets.

Siemens star to print