ICC profiles play a critical role in an imaging workflow.
ICC profiles are pieces of software code containing information that characterises each colour input or output device in an imaging workflow according to standards set up by the International Colour Consortium (ICC). They are used to define the way an output device (printer or screen for example) should represent colour for the specific combination of parameters controlling the input data it receives. Each profile defines the most saturated colours as well as the range of tones the device is able to produce in a standard colour space.
A profile for a printer will specify a precise combination of printer, ink, paper and output settings. For a screen it will define the brightness, contrast and colour values for reproduction in the light of the screen’s resolution, contrast and gamut capabilities. The best screen profiles will also take into account the user’s ambient lighting conditions.
An ICC profile can be created for each input or output medium, including input devices like scanners and cameras, display devices like monitors and projectors and outputs such as papers and other printing media.
When profiles are consistent throughout the workflow, the output will reflect the colours and tones recorded by the capture device. Without profiles, variations between devices and media will inevitably lead to incorrect colour reproduction and off-colour prints.
Photographers are generally interested in screen profiles as well as printing profiles because both play critical roles in determining how well what you see on the screen when editing images will match the printed output. In this feature we’ll start with screen profiles before moving on to printing profiles and how to obtain them and how to use them.
Monitor profiles describe how the monitor is currently reproducing colour. They are obtained by calibrating the screen. This is done with a colorimeter, which measures how the screen is reproducing hues and tones relative to a known specification.
Using a colorimeter to calibrate a monitor screen.
Monitor calibration involves measuring and, where necessary, adjusting the following settings: brightness and contrast, the brightness of the mid-tone values (‘gamma’), colour characteristics and the colour and intensity of the brightest white the monitor can reproduce. The process takes between five and 10 minutes, depending on how many display parameters you’re required to adjust.
Screen performance will usually drift a little over time, which means the values obtained at the initial calibration may not apply a month or two down the track. You can set reminders to highlight when the screen should be re-calibrated (a month is usually sufficient time for most photo enthusiasts). Re-calibration is usually faster because fewer adjustments are required.
Once the profile has been created it will be loaded into the profiles library in your computer, which is normally located in the main Library > Colorsync > Profiles folder for Mac OSX or Windows\System32\spool\drivers\color for Windows 10. Any application or device that needs to access a profile will be programmed with instructions on how to find it.
Printer profiles are specific to the printer, paper and ink that is being used. The wrong profile will result in poor print quality and increase the potential for a lot of paper and ink wastage. To help users of their products, all printer manufacturers provide ‘canned’ profiles for a range of papers (usually carrying the same brand as the printers) that can be used with each printer in their line-up.
These profiles will be installed automatically when you load the printer’s driver and will show up whenever you click on the Properties tab before making a print. They will also be accessible through your image editor whenever you print an image. Most printer drivers are set to open with a default profile which is chosen by the printer manufacturer as the most likely paper to be used or the best paper match for the printer’s ink set. Other profiles can be selected from the dropdown menu if you choose a different paper.
A typical profile dropdown Media Type menu for a wide format desktop printer. All these profiles have been pre-set by the printer manufacturer and apply to the manufacturer’s papers.
By default, most printers are set to work only with the media listed in the selection dropdown menu installed with the printer driver. Usually there is quite a long list of compatible media so it is easy to scroll down until you see the name of the paper you’re using. Selecting one of the papers will tell the printer’s driver to use the ‘canned’ profile for that paper.
When using one of the canned profiles, the printer driver can also control colour management via its default settings. Printing in this way is recommended when your image editor does not support ICC profiles. Make sure the Mode setting in the main page of the driver is set to ICM (Image Colour Management). If your editing software supports colour management, “Printer Manages Colors’ should appear in the colour management section of the printing user interface.
This illustration shows the correct colour management settings (circled in red) when you are using a canned profile and want the printer to handle colour management.
If you plan to use paper from a different manufacturer than your printer – say, Ilford paper in an Epson printer – you can often choose the closest equivalent from the dropdown list and expect to obtain satisfactory results. However, if you have a profile for the Ilford paper it’s better to turn off the printer’s colour management and let your editing software control the colour management.
It’s really important to understand that while colour management can be controlled by your photo software or the printer driver software, it can never be controlled by both. If you set up a situation where both systems are trying to control colour output, you will get undesirable colour casts in your prints.
Because this is a really critical step, you should double check it every time you make a print. If you don’t, you’ll waste paper, ink and time and end up with substandard output.
Check the illustration on this page for the two settings (circled in red) that MUST be checked.
The correct printer driver and Photoshop settings for when you want to use a media profile you have downloaded and installed.
If you’re using an image editor and want to pick a specific profile that’s not provided by the printer manufacturer, you must download it from the paper manufacturer and install it in your computer’s profiles library. All reputable paper manufacturers provide free downloads that cover profiles for most popular printers. They also provide instruction sheets covering how to install and select the profiles for each printer.
This screen grab shows part of the list of downloadable profiles for Galerie papers with the Epson 3880 printer. Note the check box for downloading installation instructions.
As long as the profile has been installed in the right place in your computer, software applications that support ICC profiles should be able to locate it and will automatically include it in their dropdown menus. You just have to click on it and select it. Note: many profiles have identifiers that don’t necessarily provide a clear representation of the name of the paper. Make sure you know the correct identifier for each paper you’ll be using.
Image editors like Photoshop list ICC profiles in the Document Profile menu in the Colour Management section of the user interface. In this illustration, the profile for printing Ilford’s Galerie Smooth Pearl paper with an Epson 3880 printer has been selected.
What makes a good profile?
There are several key factors in profiles that will influence the quality of print output. Good profiles will show all the following characteristics:
1. Accuracy. Reproduction of hues and tones should be as close as possible to what you remember from the original scene you photographed. Note: when assessing prints it is important to allow for the substantial differences in tonal range between an image you see on the screen and the same image printed on paper. Screens support a dynamic range at least ten times greater than paper. A typical contrast ratio for a monitor or TV screen is between 1000:1 and 3000:1, whereas printing papers average about 100:1.
2. Smoothness. Colour and tonal transitions must be smooth and gradual. A blocky rendition of a clear blue sky or a subject’s skin indicates the profiling target didn’t sample a wide enough range of hues and tones. While some interpolation between colours and tones is inevitable when profiles are created, the end result should always produce smooth transitions. Printers are capable of outputting hues and tones with very fine gradations so lack of smoothness can almost always be attributed to the quality of the profile in use.
3. Handling of out-of-gamut colours. Out-of-gamut colours are hues that lie beyond the range of colours the printer can reproduce. A good profile should be able to move those hues into the gamut your printer can reproduce, yielding prints that look close to what you remember of the original subject.
Rendering Intents and Gamut Controls
Rendering intents are the different methods by which colour management systems convert some or all colours in a picture to the colour space of a given output device. You’ll generally find them in the print dialog box (shown here). Of the four rendering intents available, only two are used for photographic printing: Perceptual and Relative Colorimetric. (Saturation is used for printing graphics where maximum colour saturation is required, while Absolute is used for offset press proofing.)
The four rendering intents available in a typical image editor.
Perceptual rendering aims to preserve the visual relationship between colours. The printer driver will take the out-of-gamut colours (which can’t be reproduced by the printer’s ink set) and move them to the closest in-gamut colours. At the same time it may also tweak some of the in-gamut colours slightly. It is most suitable for images with out-of-gamut colours but may cause the overall brightness of the image to change a little.
Relative Colorimetric compares the white of the source colour space to that of the destination colour space and shifts all colours accordingly. The out-of-gamut colours will be moved in to the closest in-gamut colour without changing any of the in-gamut colours.
Relative Colorimetric preserves more of the original colours in an image than Perceptual, which maintains slightly higher saturation. Perceptual rendering works best with matte papers since matte images naturally look less saturated.
Checking the Black Point Compensation button (shown to the left of the Rendering Intent dropdown menu) is important when printing with the Relative Colorimetric intent because it maps the maximum black in the image to the highest level of black the output device can produce. This ensures the full tonal gamut in the image can be reproduced.
Article by Margaret Brown (see Margaret’s photography pocket guides)