Is expenditure-neutral design with Lab colours possible in practice?

It makes absolute sense to work with Lab colour definitions and values in the design, because these define a colour in an output-neutral way. A company logo, for example, should be created in such a way that it can later be implemented in various ways, e.g. in print, on the website, on vehicles and textiles without any problems. This is common practice and the Lab colour definition offers the neutral prerequisites for this.

Unfortunately, this is still wishful thinking in most cases. Most graphics programs allow Lab colours, but these are often lost during PDF export and almost always also when an object is to be further processed in another software. PDF files and file export/import are common, however, because printers expect PDF data and designers do not work in a single software but with several tools for the application areas of layout, graphics, image processing etc.

Example Adobe Illustrator

Although it is possible to create a colour in Lab in Illustrator, the Lab information is converted to RGB/CMYK as soon as the colour is confirmed and moves to the colour list. With a trick it is nevertheless possible to permanently integrate Lab colours into a document: by creating them as a so-called "spot colour" - they then appear in the Illustrator colour palette as a separation colour with the alternative Lab colour space and are retained as such when the file is exported to other file formats (EPS, PDF).

Illustrator colour selection: Although you can create a colour in Lab, it is then immediately converted to the document colour space RGB or CMYK.

Example CorelDraw

CorelDraw allows you to work with any number of Lab colours and works well with this, but the unchanged export of this Lab vector data to other software is not possible. Objects created in CorelDraw neither as EPS nor as SVG keep their Lab colour definition, but they are saved in the RGB variant just set. CorelDraw cannot even save Lab data in TiFF, PSD or PDF files - not even in the very latest 2018 version.

Any number of Lab colours are possible in one CDR file.
However, Lab colour definitions are lost when exporting to other file formats (here the PDF export).

Example Adobe Photoshop

In Photoshop, the use of Lab as a document colour space has been quite possible for many versions. Colour lists in Lab format (ASE libraries) can also be read into Photoshop, and if one uses these colour tones in a Photoshop document, their Lab definition remains (when exporting to other formats, however, only if the document colour space is Lab or the Lab colours are created as spot colours).
A suitable exchange format for Lab bitmap files created with Photoshop is the TIFF format. Lab TIFFs can be integrated into layouts created in InDesign, for example, without any problems. Even a PDF/X-3 or PDF/X-4 created with Photoshop without colour conversion to the output destination still contains Lab data.

Photoshop colour selection

Example InDesign

It's a bit like layouting with InDesign. Colours can be defined in Lab, Lab bitmaps can be included, and exported PDFs can also contain Lab colours. In the PDF export, a Lab colour is only retained if it has been defined as a "spot colour", and a maximum of 27 of these may be contained in an InDesign document - including the spot colours within imported graphics.

InDesign colour selection

Example QuarkXPress

Even with the layout behemoth QuarkXPress, which has been known for many years, you can define Lab colours and transfer them correctly to PDF files - similar to InDesign.

Colour windows in QuarkXPress

Example Scribus

This free layout software is a pioneer in the field of colour, it can correctly handle not only Lab but also HLC colour definitions, read in large colour lists and generate colour sample pages for any number of colours. However, it is unfortunately not possible to correctly pass on Scribus data with Lab colours as a PDF. Similar to CorelDraw, Scribus converts Lab colours to the selected output destination RGB or CMYK when exporting to PDF.

Scribus colour selection

Example AffinityDesigner

Here, too, it is possible to work with Lab colours, but these are lost in the PDF export.

Colour selection in Affinity Designer

Example VivaDesigner

A Lab colour can be created in this layout programme, but it becomes CMYK during the PDF export, although the PDF format would also support Lab colours in the variants PDF/X-3 and PDF/X-4. This is especially problematic for colour tones that lie outside the gamut of the set CMYK working colour space, because these are displayed incorrectly in the PDF in terms of values and representation.

Although VivaDesigner allows output-neutral Lab colours, these are converted to the current CMYK working colour space during PDF export.

Conclusion: clear YES

Although it is possible to work with output-neutral colours in the most popular media design programmes, only Adobe InDesign and (via a diversion) Illustrator and QuarkXPress are able to transfer Lab colours into a PDF.

It is completely impossible, for example, to transfer a company logo drawn with CorelDraw in Lab to the layout of the company brochure - no matter in which layout programme the brochure is created. CorelDraw does not offer a suitable file export for Lab colours. It does work in the combination of Illustrator and InDesign, but only if the PDF file contains a maximum of 27 different Lab spot colours at the end - with several external graphics, e.g. in a brochure, this is clearly too few, and some RIPs are limited to an even smaller number of spot colours.

Device-neutral lab workflow across several programmes is hardly possible in the usual combination of bitmap, vector and layout data. There is a need for action on the part of software manufacturers, especially in the area of file formats for vector data and the number of spot colours.

What now?

As long as the Lab solution does not work reasonably, one should create one's data "neutrally" in RGB. Here, the sRGB colour space offers itself as a quasi-standard due to its universal distribution. (s)RGB data can be exchanged relatively easily as PDFs, bitmaps and vectors, and CMYK conversion for certain printing processes is a well-established and functioning practice. In any case, this makes more sense than creating separate files in the original programme for each CMYK output variant, which is still common practice in many cases.

The disadvantage of the RGB method is that, firstly, RGB is not an output-neutral definition (i.e. it must always be stated which RGB it is) and, secondly, that the RGB model is not defined in a perceptually appropriate way and therefore does not function in a perceptually appropriate way. This means, for example, that questions about intermediate colours, counter-colours or colour gradations cannot be answered without further ado. Thirdly, the RGB colour space is limited, e.g. the widely used sRGB cannot represent many cyan and turquoise tones that are possible in four-colour printing.


Author: Holger Everding, Screenshots/Consulting: Eric Soder, Peter Jäger