Five essential steps to the perfect four colour printing reproduction.
THIS CONTENT IS ALSO AVAILABLE IN INSPIRE 59 2018
What Anders Nyström, technical manager at Göteborgstryckeriet printers in Gothenburg, Sweden, doesn’t know about CMYK (short for Cyan Magenta Yellow BlacK) isn’t worth knowing.
Starting with the cover sheet of the physical copy of Inspire magazine 59 (printed on Invercote Creato 260 g/m2), we asked Anders to guide us on how to achieve the perfect four colur printing reproduction in print.
The secret is a customised and optimised original – plus a separation model that accurately describes what colour is produced by a specific CMYK combination.
1. Create a model
Create a CMYK separation model from a test print with the same conditions as the final print will have. You simply take a fingerprint of the entire printing process as a basis for the model. Standard profiles rarely describe the conditions that apply to printing on paperboard.
2. Know the source profile
In order to convert an original from one colour space to another, the source profile must be known. This is absolutely crucial to the process. If the information is missing, you can only guess what the original looked like by testing various possible source profiles. CMYK is the colour space used in traditional four colour print separation and has a smaller scope than, for example, RGB (Red, Green, Blue) which is used for computer screens.
Optimise the original. For the maximum colour range set the values in RGB to black (0) and the white value to white (255), provided the image contains white and black. Otherwise, maximise the contrast between the shadow and the highlights. Also clean out unnecessary grey components to get a purer colour reproduction. All image optimisation should be done in RGB or RAW (camera) formats.
4. Increase details
Customise the image size and apply a sharpening filter. An effective resolution up to 600 dpi (dots per inch) and a careful digital sharpening increase the details in the print.
5. Use the right format
Deliver the original to the platemaker in PDF/X format, a standard format that meets specified requirements for the exchange of print information. With PDF/X-4 the transparency is conserved with the best quality as well as important information for converting colours that are optimised for the printing process.
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