Suppose you have a job with three versions, containing a photograph that prints in CMYK. The three versions share the CMY plates, and have each their own K plate. For the photograph to print correctly in all versions, the image on the K plate of each version must be aligned precisely with the common CMY plates. The shift may be small and hard to notice when previewing the version on screen. However, it will become very obvious in print.

To quickly and easily spot such shifts, Raster Preview allows you to inspect misalignment issues in multi-version jobs by comparing version-specific plates against each other. The goal is to spot objects that were shifted across versions, especially when those versions share a set of common plates.

The idea is to keep one version - the master version - on a light table, and to lay the next version on top of it. When looking at the layered composite, unwanted shifts become immediately obvious. By switching the top layer, and comparing it against the same master, you can quickly verify the registration of the different versions. A quick way to check whether there might be a problem, before comparing individual versions, is to layer all versions on top of each other; common images should still look OK. If you notice a shift, you can then use the comparison technique to identify the problem version (or versions).

For example, suppose you want to compare the K-plate of a Dutch version with an English one. The misalignment in the text is normal, since the texts are different. However, any images on the page will be shifted to make room for the longer Dutch text.