Designing Colour Management Pipelines for Multi-Technology Print Environments

Introduction

In the current scenario, the printing environment does not depend on a single printing technology. Most organizations use a combination of inkjet, laser, offset, and digital printers, each with its own characteristics in terms of colours. Maintaining the accuracy of colours in each of the printers is a complex issue.

A colour management pipeline is an organized process that helps control the interpretation, conversion, and reproduction of colours between two or more devices. An appropriate colour management pipeline is extremely important for the packaging, textile, commercial printing, and digital publishing industries.

brands use a wide range of substrates — from plastics to metal and glass to paper and corrugated — to differentiate their products on the shelves, convey their brand identity, and grab consumers’ attention. furthermore, several different printing technologies are used to create these varied types of packaging, ranging from offset, flexo, gravure, screen, and, increasingly, digital.

The packaging process is becoming increasingly convoluted, and achieving the right colour with different substrates and printing technologies can be challenging for brand owners, especially colour consistency.

Lack of colour consistency can adversely affect your brand’s image, with consumers ignoring products with inconsistent colouring. Bear in mind that, according to the Pantone Colour Institute, more than 65% of purchasing decisions involve colour. Brands must get colour consistency right.

Challenges in Multi-Technology Print Environments

Device Colour Variability

Devices may use different colour profiles, such as sRGB, Adobe RGB, or DCI-P3. These profiles define how colours are interpreted and displayed. If two devices use different profiles, the same colour may appear different based on below categories.

· Ink composition

· Printhead technology

· Substrate materials

· resolution

Adjustments to brightness, contrast, and colour temperature can lead to variations in how colours are seen. For example, inkjet printers produce colours using droplets of liquid ink, while laser printers use toner particles fused onto paper. These differences result in distinct colour range.

Substrate Differences

It’s basically the “base layer” that receives the ink. Substrates can be paper, cardboard, plastic, metal, fabric, film, or any other material used in printing and packaging. Different substrates absorb ink differently, which affects colour, durability, and overall print quality.

Workflow Complexity

In a production system, colour data may go through several processes:

· Design Software

· RIP (Raster Image Processor)

· Colour Conversion Engine

· Print Controller

· Printer Hardware

If colour transformation is inconsistent at each stage, the result will vary greatly

Key Components of a Colour Management Pipeline

1. Device Profiles (ICC Profiles)

Device profile is a description of how a device works with colours. An ICC profile is used for translating colours between device colour spaces and standard colour spaces.

ICC profiles include,

· Input device profiles (scanners, cameras)

· Display device profiles (monitors)

· Printer device profiles

Using accurate printer ICC profiles is vital for ensuring that the printed image is as close as possible to the original design.

2. Standardization of Colour Space:

It is necessary to use a standard colour space as a reference throughout the process.

The standard colour spaces include:

RGB colour space — used for digital displays and design applications

CMYK colour space — used for all types of printing processes

CIELAB (Lab) — a universal colour model

The standard method for standardization is as follows:

3. Raster Image Processing (RIP):

A raster image processor (RIP) is a software that translates (rasterizes) computer vector files (InDesign, Illustrator, Photoshop, PDF, JPG, etc.) to a raster image also known as bitmap that is composed out of a matrix of dots that the printer can understand and print. The main RIP operations are:

· Colour space conversion

· Halftone and screening

· Ink limiting

· Resolution scaling

In a multi-technology setup, the RIP system has to support a number of output profiles and colour strategies.

4.Colour Calibration:

The aim of colour calibration is to measure or adjust the colour response of a device (input or output) to a known state.

Printers need to be calibrated regularly for accurate results. Calibration includes the Printing test charts, measuring colours using spectrophotometers and making necessary adjustments to printer settings. Automated calibration helps ensure consistency in results for batches of production.

5. Gamut Mapping:

The gamut of different devices varies, and some colours may not be printable on certain devices.

Gamut mapping is performed using algorithms, and the colours are adjusted so that the visual result is similar.

The strategies for gamut mapping include:

· Perceptual rendering

· Relative colourimetric rendering

· Absolute colourimetric rendering

· Saturation rendering

The correct rendering intent is essential for accurate results.

ICC profiles at fleet scale: creation, storage, version management:

The International Colour Consortium (ICC) determined the architecture and format of the profile and these are used throughout colour management workflow.

An ICC device profile contains the information needed to transform colour data between device values and a device-independent CIE-based colour space. To make an ICC profile for a colour device you need a profiling package. This normally includes a measurement instrument, a test target, and a software program which can read the measurements and generate the profile.

For an output device (display or printer) colour patches are displayed or printed and then measured. For an input device (scanner or camera) the test target supplied with the profiling package is captured and measurements of the target will usually be available within the software.

Once the software has the device data and the corresponding measurements, it proceeds to create the data structures which form the profile. Depending on how complex the device is to model, the profile may be anything from 1K to several MB in size.

An ICC profile uses a tagged format, and consists of a header plus individual tag. Tags can be informational, numeric, required, or optional.

Currently, two versions of profiles are widely used, namely the v2 and the v4.

The ICC profile v2 was introduced in June 1994 and v4 was introduced in December 2001.

The major improvements introduced in v4 compared to v2 are as follows:

Ø Colourimetry needs to be measurement-based, and no preference is allowed.

Ø The standard Perceptual Reference Medium (PRM) gamut is introduced, and it is a must to render to and from the standard PRM using perceptual rendering intent. The dynamic range of PRM is high quality print.

Ø PCS is always D50 colourimetry, and for v4, it is clarified that non-D50 colourimetry needs to be chromatically adapted to D50 using the ICC Bradford transformation.

Ø The correct process for display profiles has been clarified.

Ø New look up table (LUT) specifications are introduced to ensure correct invertibility of older LUTs.

*Spectrophotometer integration: reading Lab data programmatically**

For printing manufacturers, a professional spectrophotometer for printing or a dedicated colourimeter in printing allows for highly accurate print colour measurement, ensuring consistent colour reproduction across all batches. Moreover, using a colourimeter or spectrophotometer can minimize material waste and significantly improve production efficiency.

Integrating a spectrophotometer into a software workflow allows automated measurement of printed colours and direct access to *CIELAB (Lab) values for colour verification, calibration, and ICC profile generation. In modern print environments, this integration is often done programmatically through SDKs, serial communication, USB APIs, or network protocols**.

Below is a practical explanation of how *Lab data can be read programmatically from spectrophotometers**.

Parameter Meaning

L* Lightness (0 = black, 100 = white)

a* Green (−) to Red (+)

b* Blue (−) to Yellow (+)

Integration Architecture:

Conclusion:

However, it is important to understand that developing an effective colour management pipeline is of utmost importance in ensuring colour consistency in today’s multi-technology printing environments. The use of different technologies in printing, including inkjet, laser, offset, flexography, and digital printing, has made it increasingly difficult to manage colour accuracy in printing.

A well-structured colour management pipeline involves different components, including standardized colour space, ICC device profiles, raster image processing, calibration, and spectrophotometry. The use of these components in colour management is aimed at ensuring colour interpretation, transformation, and reproduction in printing. The management of ICC profiles, in particular, poses different challenges, including managing different versions of ICC profiles in a fleet of printers. The use of spectrophotometers, on the other hand, enables the use of Lab* colour values in ensuring colour accuracy in printing. The use of spectrophotometers in colour management enables production systems to monitor colour accuracy in printing. The use of colour management systems in printing is expected to become even more intelligent in the future as printing technologies continue to become increasingly intelligent. The next generation of colour management pipelines is expected to be even better, with different technologies, including analysis, services, and real-time production.

Future explorations in this area will focus on several important topics:

• Delta-E algorithms compared: CIE76, CIE94, and CIEDE2000 — implementation strategies and practical guidance on when each algorithm should be used.
• Colour database design: structuring systems to manage colour targets, tolerances, measurement datasets, and long-term trend analysis.
• Closed-loop correction: building automated pipelines that convert measurement data directly into press adjustments to maintain colour consistency during production.
• REST API design for colour management services using JSON-LD, enabling interoperable colour services across distributed printing systems.
• Visualisation techniques, such as plotting colour drift and measurement trends using tools like D3.js for better monitoring and analysis.

Therefore, it is envisioned that by marrying robust colour science with modern software engineering techniques, future colour management pipelines will facilitate the creation of highly automated, scalable, and reliable printing systems that can reproduce precise colour fidelity in ever more complex environments.

Prepared By

Vijayalakshmi R

Senior Software Developer

Ramarson Technology developers LLP