Capture to Output – Colour Communication? (Part One)
By David Crowther
From the moment of digital capture, right up until the time of digital output, close attention needs to be given to colour communication. Hang on, you say, colour communication? Is this something new? What about colour management? Well, colour management is really about communicating colour accurately from device to device in an ICC enabled workflow. This communication of colour allows you to predict what will happen to colour sooner in the workflow, therefore empowering you and your workflow processes to make better decisions concerning colour earlier in the production process. This is the true value of colour management.
Colour management simply describes colour – it does not necessarily FIX bad colour. There is a common misconception by those under-informed about colour management that the colour management system “knows” how a device should reproduce colour – therefore the process of building a profile will make the device produce colour correctly. Not true. Colour management will do a great job of reproducing bad colour accurately through the system. Fixing poor originals will always require the skills of a good colour “technician”. In fact, the best person to put in charge of your colour management program will always be your best colour specialist – as good colour management requires the same skill sets.
With the aid of the accompanying workflow diagram I will aim to define and describe what you need to be aware of as you step through from Capture to Output. The workflow outline will not suit everyone, but, for photographers especially, I believe that these are the steps where colour management plays a critical role.
The workflow starts at the point of RAW digital capture. Capturing in RAW enables a photographer far greater choices and options than previously thought possible. Utilizing RAW processing capabilities, the photographer gains control over white balance, exposure, brightness, contrast, saturation, chromatic aberration, detail, tonality and more. All of this can be done with different settings to suit the mood, setting and type of image captured. And the bonus is that these tasks can be completed back in the comfort and convenience of ones studio or workplace. (Some location photographers have commented on the impracticality of lugging a complete computer system around in remote area, to carry out RAW processing. A G5 and 21” Apple Cinema Display from the back of the Land Rover to a dusty table in the Simpson desert, running from a generator? Possible, but probably not practical. What about using a laptop on location? Most laptops can be colour managed with a fair degree of accuracy.)
So, processing RAW files requires an accurately calibrated and profiled display. All judgement is based on the image seen on the display. Without a calibrated profiled display you may as well be in a darkroom with the lights out;
You can feel what you are doing, but you are working blind! Granted, one can re-process RAW files with different settings, but for the sake of productivity (and sanity), you would hope to speed up and even batch process RAW files.
With the RAW processing complete, you now have the opportunity to carry out RGB retouching, editing and colour space conversion to CMYK, if required. The best way carry out these steps is to utilize soft proofing. This is one of the great unsung benefits of PhotoShop. The soft proofing option allows you to simulate device output on the display. How is my RGB image going to look in Newsprint or commercial CMYK sheet-fed offset or publication web offset or that new solvent inkjet printer the bureau has down the road? All of this can be accomplished with an accurate on screen simulation. Here colour management comes to the fore. To achieve an accurate soft proof, a stable, accurate, calibrated and profiled display is required, together with a valid device (e.g. print output) profile. Soft proofing can save you valuable time and dramatically cut down on wastage of materials. It also allows you to continue working in your favourite RGB working space and then simulate on the display how your image will look when printed or converted to CMYK. You can use the complete array of retouching and editing tools and plug-ins available in RGB - and make an informed judgement on the result - without actually converting or outputting the image.
What you view will only ever be a simulation. The accuracy of the simulation is dependent on many things. Monitor calibration settings – White point, 5000k, 6500k or something completely different – Gamma, 1.8 or 2.2 – White Luminance, 120 cd/m² or something completely different, Black luminance 0.2 cd/m² or something completely different. Does the display have a hood to help eliminate flare and reduce the effect of the ambient lighting? Is the monitor the brightest thing in the room? Or is it competing with a window for brightness? Are the best practice methods being used to assess the soft proof image? Is a comparison between the soft proof and hard copy being carried out with a suitable viewing system set up correctly for soft/hard proof direct comparisons? These are the main points to consider when setting up and using soft proofing.
But what should your expectations be with regards to soft proofing?
You should set your expectations quite high! LCD display technology is rapidly developing and marked improvements are measured in almost 6 monthly cycles.
I may be bold here, but within the next 12-18 months, soft proofing will definitely gain far greater acceptance and usage for proof-to-press colour match sign offs. Many larger print buyers will be following this route in an effort to gain greater efficiency and drive down costs in an increasingly competitive print market. This may not mean too much to you as a photographer, but it does bode well for the quality and consistency of colour we can expect from high end displays. I should mention that another major factor that reflects the quality of the soft proofing achieved is the display itself. Today, you get what you pay for. Hardware calibrated displays, like the Quato Intelli Proof range and the Eizo CG range should be at the top of your shopping list if you wish to make soft proofing a reality.
Nowadays, there are specifications for monitor set up and soft proofing, outlined in ISO 3664 and ISO 12646. Together with these is the recently released UGRA (The Swiss Centre of Competence for Media and Printing Technology) Display Analysis and Certification Tool. This control tool has been developed with a focus on the evaluation of the quality of the display (monitor). The control tool is provided in the form of software and you must use a measurement device such as a GMB Eye-One or X-Rite DTP-94 Colorimeter to complete the measurement routine.
In the next issue I will endeavor to round off this colour management workflow “crash course” by concluding with the important colour management considerations that need to given to the output stage.
David Crowther is the manager of Chromaticity Australia.
Chromaticity Australia offer colour management training and consulting. http://www.des-pl.com.au/
David writes a regular Workshop page for Digital Reproduction magazine.