CMYK Image File Conversion

RGB files will more often than not be converted at some point into CMYK data for output via a printer that uses cyan, magenta, yellow and black base colours to create an image. Given that the CMYK colour space is inherently smaller than RGB, creating RGB files that will convert well into CMYK requires perception and judgement. As with the process of image capture itself, decisions have to be made as to which tones and colours to emphasise in order to create the most effective result. Unfortunately, there are no fixed rules or universal control settings for this, as each image has its own unique characteristics. RGB files that are created without such forethought will tend to be flat and lifeless when converted to CMYK.

There are an almost infinite number of different colour standards or output profiles that can be used to describe print devices. In order to be truly accurate, colour profiles need to be customised for the particular device, rather than simply generic for a printer model or type.

However, it may not always be possible (or practical) to convert RGB data via a custom created output profile. The vast majority of commercial CMYK image files will be destined for reproduction on some form of lithographic printing press.

CMYK colour charts & litho printed book - Hugh Jones

CMYK Image File Conversion - Price Guide

From existing RGB image files. Prices in Sterling, excluding VAT (where applicable). Please contact us for an estimate on your specific project.

Watercolour detail with & without USM - Sara Nunan

As the precise press to be used may be unknown, and because of operational variables which affect the colour gamut of press production, it is often taken as sufficient to adopt a generic profile that broadly encompasses the type of press, inks, and ink densities used.

As with the RGB to CMYK conversion process itself, the application of appropriate unsharpmasking to a CMYK image is something of a black art. It is an accepted fact that, for best results, image sharpening should only be applied as a final stage when the image is at the correct size ready for output. Nearly all image files will require some degree of digital software 'sharpening' in order to create an eye catching printed image. Factors that need to be taken into account here include:

  • sharpness and detail in the image file
  • size of reproduction
  • halftone screen frequency (if relevant) for the printer

We can advise on appropriate colour profiles for the intended printed output and supply drum scans ready converted to CMYK including appropriate sharpening if required.

See also:

RGB to CMYK conversion - price guide