ACCURATE COLOUR COMMUNICATION

Print is one of the only manufacturing processes where the client is deeply involved. This especially relates to colour. However, colour is subjective and can be difficult to describe accurately. With colour variation, each individual has their own idea of what is correct and acceptable.

PRINTING United Alliance is dedicated to helping its members – and the industry at large – to navigate issues such as these. The Alliance’s expert staff and partners in education and training, repeatedly maintain that setting the right colour expectations with clients is vital. It can reduce rework and save time and money.

“Colour printing is a reproduction rather than an exact match process”

Managing colour expectations begins before any job is sent to the printers. It is a conversation – and often an education – between sales/customer service and the client. Using the incorrect vocabulary, 
sets unrealistic expectations that can be difficult or impossible to overcome in production. When communicating colour, it is best to remove the word ‘match’ from the conversation. Colour printing is a reproduction rather than an exact match process. By definition, a reproduction is a ‘likeness or close facsimile’. How closely a particular colour can be reproduced, varies widely. Some colours are reproduced more faithfully than others on the printing press.

The visual sensation of colour can be as subjective as touch, taste, feel or sound. Everyone experiences colour differently because there are many variables. These include light source, surrounding colours, 
the viewer’s mood, past experiences and differences in visual ability. All of these influence colour perception. However, even 
if everyone saw colour in the same way, 
its description and interpretation would be different.

“Managing colour expectations begins before any job is sent to the printers”

As printers, clients often have difficulty describing the colour effects they desire. It is often easier for them to describe what they do not want. This is the primary reason that proofs are required.

It is at this point that colour communication can break down. Too often, vague terms such as ‘flat’, ‘muddy’, ‘blown-out’, too warm’, ‘too cold’ and ‘make it jump off the page’ are used to describe colour corrections. Each one can mean very different things to different people. Describing colour using imprecise terminology can create communication problems, delays and rework.

“Discussing Delta-E (dE) must be a part of the colour conversation”

PRINTING United Alliance suggests that when a colour is described as flat, blown out or muddy, it generally means that the problem is associated with colour contrast. Instead of flat, ‘lacking in contrast’ is a more precise term. Blown-out can be better described as ‘lacking highlight detail’. Instead of muddy, describing the image as ‘too dark’ is a more accurate choice.

In addition, colours can sometimes be described as too warm or too cold. Too warm can mean many different things. Therefore, warm colours are more accurately described as ‘magenta, red or yellow’. Too cold is also an unclear way to describe colour. ‘Too much cyan, green or blue’ is a better option.

Discussing Delta-E (dE) must be a part of the colour conversation. dE is a single number, expressed as CIELAB coordinates. It represents the distance between two colours. The higher the dE value, the greater the distance between the two colours. Theoretically, this can mean a more significant difference in the visual colour.

For example, a dE of zero implies that there is no difference between the two measured colours. A dE of one is the smallest colour difference the human eye can see. This assumes that the observer has an excellent ability to perceive differences in colour.  A dE value of less than one is imperceptible. In contrast, any dE greater than one will be noticeable. 

Unfortunately, it is not that simple and depends on the colour itself. While some colour differences with a dE greater than one are perfectly acceptable, others are not. dE measurements can be very helpful where there is a difference between a previously printed job or proof and the current job. It is also useful when considering how effective a profile is for printing or proofing. In addition, it can help to remove subjectivity when comparing and communicating colour. Furthermore, dE measurements can be useful where a device has drifted over time or when variation has occurred during a single print run. 

“What is acceptable from the client’s view, may not be feasible from a production standpoint”

Often, the client is the driver in acceptable colour variation. However, what is acceptable from the client’s view, may not be feasible from a production standpoint. The raw materials used to print jobs, such as paper and ink, are not perfectly consistent and contain variations. There are also normal variations inherent in printing equipment. Depending on the process used, variation can range from low to high. For example, an offset-printing press can have a colour variation of 2.5dE throughout a press run. On the other hand, toner-based devices and inkjet presses have fewer print variables. They are more consistent and generally print at a 1.0dE.

Before communicating what is possible and what is not, it is important to understand the equipment’s capabilities. Measuring a device over a period of time will provide great insight into how consistently a device performs. Once this is established, a customer’s individual needs can be considered to establish a reasonable, attainable, colour-printing tolerance.

“Colour is subjective and difficult to explain and express”

Printing is unique to all other forms of manufacturing – the customer is actively involved in the process and colour decisions. Colour is subjective and difficult to explain and express. Everyone has their own interpretation. Setting realistic expectations begins with resetting vocabulary, communicating colour accurately and establishing a baseline for acceptable variation and reproduction. 

To explore further, the How to Evaluate and Communicate Colour course is available on PRINTING United Alliance’s eLearning platform at www.ilearningplus.org.