Some printing processes do not use CMYK process inks at all, instead only spot inks are available, and sometimes even a relatively small number. Furthermore, in some cases half-toning does not work at all, and thus iit may not be feasible to overprint spots with each other to achieve mixed ink colors.
This may be due to the way the printing process works, but could also go back to cost considerations, for example when imprints on small give-away items must be as inexpensive as possible and thus use only two spot colors.
For such scenarios, print ready PDFs should only use a specific number of spot colors, and always at a 100% tint value.
How to go from arbitrary images or PDFs to print-ready PDFs using only a small number of spot colors?
As any print service provider will try not to decline a print job just because the print file has not been prepared perfectly well, the question in this context is: how to turn an arbitrary PNG or JPEG image, or an arbitrary PDF, into a print ready PDF file that only uses a specified number of spot colors, none of them overprinting each other, and each of the spot colors with a tint value of 100% – while maintaining the overall appearance of the orginal image or PDF as well as possible?
This is where the new Spotify feature in pdfToolbox comes into play. Based on a complex analysis process, and controlled by a number of user configurable parameters, it derives the spot colors that offer the best appearance match, and assigns these to the respective areas of the original PDF, in order to provide a clean looking and pleasing result.