Setting up a Colour Managed Workflow

Serious photographers with high-quality, dedicated photo printers need a working knowledge of colour management and digital workflow strategies to obtain the best prints from their digital images. The term ‘workflow’ in this context starts with image capture and extends through a chain of devices and media that include your computer monitor, editing software, printer and the paper you print on.

Each link in this chain must connect correctly if you want the pictures you print to have the same colours and tones as the shot you captured. Control is required at each step in the workflow to ensure the best possible prints.

Step 1: The Camera

Effective colour management starts at the camera and involves selection of settings that will provide you with the maximum amount of image data to work with. This means shooting with the highest resolution and quality settings your camera offers (using the RAW setting if possible, for reasons outlined in Printing Raw Files) and selecting the correct colour space. There are good reasons for each of these choices.

High-resolution images provide more options for editing and printing than low-resolution shots. Raw images can be converted into high bit-depth TIFF files, which contain more than three times more data than the highest-resolution JPEGs. Your editing flexibility is greatly increased.

Colour space selection is slightly more complex. The default colour space setting for most digital cameras (and the only colour space provided on the majority of compact digicams) is sRGB. Enthusiast cameras and digital SLR models usually offer at least one additional colour space: Adobe RGB (1998). The colour gamut of Adobe RGB is wider than sRGB (as shown in the diagram on this page), allowing the camera to record a greater range of colours and tonal nuances. This, in turn, leads to better prints that more accurately reproduce the colours in the original shot.

The above plot shows the differences in colour gamut between Adobe RGB (the outer triangle) and sRGB (the inner triangle). All hues inside the triangle can be reproduced in the designated colour space.

Step 2: The Working Environment

When you move your image from your camera to a PC, the lighting in your work area can affect the way you see the image’s colours and tones. It’s best to work in lighting that is dimmer than normal room lighting because bright ambient light can cause the colours you see on your monitor to look washed-out and flat – so what you see may not be what you get in a print. Make sure no light is reflected off the surface of the monitor. Note: To ensure consistent results, maintain the same type and level of lighting when you calibrate your monitor and edit and print your photos.

Step 3: The Monitor

What type of monitor do you use? Until recently, serious photographers used CRT screens because, although they couldn’t cover the gamut of the standard sRGB colour space (which is used by all digital cameras) the best ones came pretty close. The latest professional LCD screens support a much larger colour space, which is wider than sRGB and comes close to Adobe RGB 1998. Although still relatively costly, they are the best option for photographers seeking total colour management.

All monitors require re-calibration and profiling every month to ensure the hues and tones you see on the screen will match those in the print. This is one of the main challenges in creating a colour managed workflow. Calibration produces an ICC profile that can be used by your editing software to output the correct image data to the printer’s driver.

Two types of tools are available: software programs and colorimeters or spectrophotometers. Both can be used with CRT screens, which are easier to calibrate because they have more adjustments. LCDs tend to be more stable than CRTs but they usually need to be calibrated with a spectrophotometer (see below).

The illustrations above show how the wizard-based instructions make it easy to calibrate a monitor with Adobe Gamma.

The most commonly-used software applications are the Adobe Gamma utility, which is supplied with most Adobe software and QuickGamma, which can be downloaded from www.quickgamma.de/infoen.html. Both have the advantage of being free of charge but they’re less accurate and versatile than a spectrophotometer.

Adobe Gamma can be found in the Gamma control panel for Mac or Monitor Setup in PC systems. Whereas Adobe Gamma actually creates an ICC profile, which is used by the computer’s operating system as the default monitor profile, QuickGamma (which is for Windows only) stores colour look-up data in the Windows registry. This is used by Windows to produce correct colours for the sRGB colour space (which is the default colour space for the internet and most digital cameras). Other gamma charts – and lots more information on colour management – can be found at www.normankoren.com. Ian Lyons (www.computer-darkroom.com), Andrew Rodney (www.digitaldog.net) and Bruce Fraser (www.pixelgenius.com) also provide useful information on their websites.

Entry-level colorimeters and spectrophotometers can be purchased for between $350 and $500. The most readily-available models are the Gretag-Macbeth EyeOne Display 2 (RRP $500) and the Pantone Colorvision Spyder (RRP $357). Each consists of a metering device that measures the colour of the light emitted by a PC monitor and a software application that drives it and creates the ICC profiles that are loaded automatically into the display settings. The two colorimeters and spectrophotometers come with step-by-step tutorials to help novice users – and the EyeOne Display 2 includes a facility for measuring the intensity of the light in the working area and applying it to the calibration.

A spectrophotometer makes it easy to calibrate your monitor at regular intervals.

Colorimeters and spectrophotometer calibration is more precise and reliable than software-based calibration, although the latter can work well under ideal conditions. Both colorimeters and spectrophotometers have reminder settings that encourage users to check their monitors regularly to ensure their system will produce prints with repeatable colour. This minimises paper and ink wastage and could allow the average photo enthusiast to recoup the initial purchase cost of the colorimeters and spectrophotometer within a couple of years.

Regardless of whether you use a spectrophotometer or calibrate manually, the first step is to warm up your monitor for at least 30 minutes and ensure your room lighting will remain constant throughout the calibration process.

Step 4: Printing

Once you’ve set up your printer correctly, with the correct profile selected for the paper and the correct printer controls in the driver, the next step is to press the ‘Print’ button. If the option is available, most photographers check the Preview button to ensure the image is correctly sized and positioned on the paper before committing to a print. This step can save both time and resources (ink and paper).

Most printers will offer a choice of high-speed and normal speed printing. For the best quality prints, select the latter mode – even when proofing images and making test strips (see Money-Saving Strategies for Digital Printing). Keep an eye on the ink levels monitor – if one is provided – so you can change a cartridge before it runs out. Some printers will stop automatically when this occurs; others continue printing but the image quality suffers when the proper number of inks is not used.

Step 5: Evaluation

As the prints emerge from the printer, lift them carefully from the tray and set them to one side to dry. Avoid touching the printed surface while you do this as some types of inks may take several minutes before they become resistant to smudging. Some may also take even longer for their colours to stabilise. You must always allow this to occur before evaluating any prints.

Although professional photographers who work in studios usually install special viewing stations for checking the colours and tones in prints, for amateur photographers, any location that is evenly lit with normal daylight will suffice. The key criteria are that the light be bright enough for you to see all the details in the print (particularly highlight and shadow details) and evenly distributed all over the print’s surface.

It is generally best to avoid viewing prints in artificial lighting as it can produce colour casts that may cloud your judgment. However, some photographers find a daylight fluorescent tube comes close enough to simulating daylight conditions – provided the viewing environment itself is relatively neutral.

If prints are to be displayed under artificial lighting, you should also check how the print will look under the actual lighting conditions in which it will be displayed. You may need to make some slight adjustments to brightness, contrast and colour balance to ‘optimise’ the print for its viewing situation.

Reference Cards

Reference cards printed with calibrated values of a range of hues and tones can be handy for fine-tuning monitor settings and will help you to make what you see on-screen even closer to the printed result. Because monitors are backlit, they can display a much wider range of tones than you can print. Consequently, images that look good on a monitor often fail to print well because colours are less vibrant in reflected light. With a reference card you can narrow the gap between the on-screen view and the print. You can also fine-tune colour accuracy.

GretagMacbeth’s ColorChecker cards have long been used by photographers as a colour reference. Prices start at over $100 for the smallest 24-patch reference card and extend to around $550 for a 21.6 x 27.9 mm card with 140 colour and greyscale reference patches. Cheaper ($66-$90) but less versatile, are the Kodak Q13 and Q14 Greyscale and Colour Separation cards.

But neither is as versatile as a recent addition to this category from Canadian firm, Pixel Place (www.pixelplace.ca or www.perfect-pixs.com), whose Perfect Pixs cards are much more affordable. The standard three-card kit, which contains colour, greyscale and white balance reference cards, sells for less than $A35, while the five card kit which adds a focusing target plus additional colour and greyscale references, costs around $83.50. Shipping costs just under $14.50.

The cards are supplied with a CD containing reference images of each card plus instructions for using them to calibrate monitors. You can also display these reference images on your monitor and compare them with the printed cards to detect colour casts and tonal compression. The cards themselves can be photographed, either in the first shot or before a shooting session, to provide a colour or greyscale reference for the ambient lighting in which the shots are taken. This can be particularly useful in mixed lighting conditions.

Finally, photographing a reference card allows you to assess the accuracy of your camera’s exposure system. If you cannot see differences between the zones at the right end of the greyscale zone reference, over-exposure is occurring. When zones at the left end of the scale appear to merge, correct for under-exposure.

Shots of calibration cards can also be used to fine-tune colours and tones when editing images, using the eyedropper tool to select relevant patches in the reference target. Overall, a set of reference cards is one of the cheapest and most valuable tools a photographer can possess.

Post-printing Handling Advice

Follow these simple precautions to keep your inkjet prints as bright and colourful as the day you made them for years to come.

• Never dry your prints using a hair drier;
• Never dry your prints by placing them in direct sunlight;
• Once prints have dried, stack them interleaved with plain office paper and allow them to ‘cure’ for 24 hours prior to framing;
• Wherever possible, avoid exposing your prints to atmospheric contaminants or direct sunlight;
• Use acid-free archival sleeves for photo print storage;
• Use acid-free mats between the photo and the frame’s glass;
• Framed pictures are better protected from atmospheric contaminants if mounted under glass;
• Don’t display or store your prints outdoors;
• Don’t store your prints where they are exposed to chemicals, such as in a darkroom;
• Protect prints from ozone sources, such as monitors and TVs, air conditioners or other sources of high voltage electricity;
• Avoid framing photos when humidity is high, as condensation may form behind the glass.

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