April 6, 2017 | Author: mariosagastume | Category: N/A
Colour Management An introduction to colour management using NedGraphics’ software
Notice NEDGRAPHICS reserves the right to make changes to the product described in this manual at any time and without notice.
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T ABLE OF CONTENTS 1.
Colour management ...........................................................................................4 1.1. About Colour management .........................................................................4 1.1.1. Why colour management.....................................................................4 1.1.2. CMS Engines ......................................................................................4 1.1.3. Profiles ...............................................................................................4 2. Colour management dialog.................................................................................5 2.1.1. CMS selection.....................................................................................5 2.1.2. Profiles ...............................................................................................5 2.1.3. Settings ...............................................................................................6 2.1.4. Toolbar ...............................................................................................7 3. The ICM Engine.................................................................................................8 3.1. Obtaining profiles .......................................................................................8 3.2. Installing profiles ........................................................................................8 3.3. Enabling profiles in Windows.....................................................................9 3.3.1. Monitor profile....................................................................................9 3.3.2. Printer profile......................................................................................9 3.4. Configuring the printer driver .....................................................................9 3.5. Configuring the Engine ...............................................................................9 3.5.1. Selecting profiles ................................................................................9 3.5.2. Rendering intent..................................................................................9 3.6. Selecting the application printer................................................................10 4. Third party profiling software...........................................................................11 5. Glossary...........................................................................................................12
Colour Management 1.
C OLOUR
1.1.
About Colour management
MANAGEMENT
1.1.1. Why colour management A computer monitor device has a certain range of colours it can display; this is called the gamut of the device. Colours it can display fall inside its gamut, colours it can’t display fall outside its gamut. As a monitor can’t display all colours visible to the human eye, a printer device can’t print all colours visible on a monitor. In some cases the printer can even print colours which can’t be shown on a monitor. These device limitations come into play when for instance you want to accurately print colours you see on your monitor but fall outside the printer gamut. A Colour management system can help you identifying these situations and, in most cases, offer you a better alternative. Bear in mind that it is no magic going on and that your printer will never print colours it just can’t print because of its hardware limitations. Another reason for starting to use colour management could be when a company has to communicate colours from one office to another, or maybe to its customers. As soon as different hardware needs to produce the same colours, these colours need to be managed. For the most accurate colour perception it is essential you work in a controlled environment. Sunlight, office lighting and all surrounding colours are the most important among numerous aspects which influence the way you perceive colours.
1.1.2. CMS Engines A Colour management system (CMS) uses a colour engine to do the actual work of converting colours from one device to another. The NedGraphics CMS currently supports three different engines you can choose from. These engines are described below. Standard Engine The Standard Engine is shipped with all applications and does only basic colour operations. It does not support exact colour matching or colour proofing. NedGraphics Engine The NedGraphics Engine is sold separately and once installed it can be used by all NedGraphics applications. ICM Engine The ICM Engine is sold separately and once installed it can be used by all NedGraphics applications. The engine supports the ICC standard resulting in a great amount of third party tools and profiles. For instructions about installing and configuring the ICM Engine, see chapter 3.
1.1.3. Profiles Characteristics of a device can be stored into a separate file, called a profile. A colour engine supporting profiles can use this information in the process of colour transformation between different devices. The format of a profile and how to obtain a profile for your device depends on the kind of engine being used. See chapter 3 for information about the ICM Engine and profiles.
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Colour Management 2.
C OLOUR
MANAGEMENT DIALOG
Since the introduction of our new colour management system, all NedGraphics applications contain a dialog to set up the colour management. The settings you make in this dialog are system wide, meaning that it affects all NedGraphics applications running on that computer system, providing that the application has colour management enabled. The dialog can be activated by selecting Colour management, typically from the Tools menu. It enables you to see and change the settings of the currently selected colour engine or to select a different engine.
2.1.1. CMS selection The CMS combo shows all available colour engines which are installed, and the currently selected one. To change the current colour engine, select it in the CMS list.
2.1.2. Profiles If an engine supports profiles, they can be selected for the monitor and printer(s). For every printer available on the system a profile can be associated. NOTE: only the settings as shown in the dialog are stored in the engine when closing the dialog (by pressing OK). This means that settings in a colour engine other than the selected one and profiles associated with printers other than the selected printer are not saved.
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Colour Management
2.1.3. Settings Render intent The render intent is the method the engines use when mapping out-of-gamut colours back into gamut. This way you can control what happens with colours you can see on your monitor but your printer is unable to print. Out-of-gamut The out-of-gamut warning is an option to indicate out of gamut colours in the application colour palette and the colour picker menu. When checked, out of gamut colours are indicated with a cross, or a yellow area in the palette. These colours as shown on the monitor cannot be printed on the currently selected printer, and will be mapped into gamut using the selected render intent. The fact whether a colour falls in or out of gamut is determined by the profile of the selected printer.
Yellow out-of-gamut indicator in the application palette
Out-of-gamut cross in the Colour menu
Proofing The proofing option shows the colours in the application palette and design, as they would appear on paper, printed by the currently selected printer with the currently selected render intent. This can be used to see the differences between printed colours and monitor colours, i.e. proof the printer colours on the monitor. Out-of-gamut colour When the proofing option is enabled, all out of gamut colours can be indicated by selecting the last option. The user should pick a colour that is not present in the design to indicate all out of gamut colours with that specific colour. Typically this is a very bright or very dark colour, depending on the colours of the design.
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Colour Management
2.1.4. Toolbar Applications with colour management support often also have a toolbar offering shortcuts to quickly enable or disable the settings discussed in section 2.1.3.
Toggles out of gamut warning for colours
Toggles proofing of colours
Toggles out of gamut indication of colours
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Colour Management 3.
T HE ICM E NGINE
3.1.
Obtaining profiles
There are several ways to obtain profiles for your monitor or printer. Generate profile The best way to obtain an accurate profile for your hardware is to generate it using professional profiling hardware in combination with third party software. This way the profile will be specific for your monitor or printer, and in case of printer, customized for the ink and paper you used during generation. For more information about obtaining software to create profiles see chapter 4. Manufacturer profile Most hardware is shipped with an ICM profile created by the manufacturer, or the manufacturer offers profiles for download on its website. Beware that these general profiles cannot possibly incorporate specific variations of your hardware, since they are at best intended for a whole product line, not for individual devices. Also the aging of hardware can change the way it produces colour and using a general profile also does not take this into account. Profile substitution When there is no profile available for your hardware you can try using a standardized profile such as the sRGB profile. This profile is an attempt to catch the most common characteristics into one profile, which could ultimately lead to successful exchange of accurate colour information across devices. The sRGB profile does not need to be installed; it is shipped with your Operating System.
3.2.
Installing profiles
To be able to use ICM profiles in NedGraphics applications using the ICM Colour Engine, they first have to be installed in the Operating System (Microsoft Windows). To do this, follow these steps: 1. Obtain a profile as described in section 3.1, at least one for your monitor and one for every printer configuration (printer, dpi, paper type). 2. Locate the profile file with the extension .ICM or .ICC with the Windows Explorer. You can find the file where you saved it before in section 3.1, or from the manufacturer cd-rom. 3. Right-click with the mouse on the file to open its popup menu 4. Select the first option Install profile to install the profile in your Operating System. Please note that nothing seems to happen when you click, this is expected behaviour. You can check if the profile has been installed correctly by right-clicking again on the same file and look at the first option. If it is now named Uninstall profile, the installation of the profile was successful and you can close the popup (do not click on Uninstall of course).
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Colour Management 3.3.
Enabling profiles in Windows
After the profiles are installed in Windows they need to be enabled for the devices you want to use them with.
3.3.1. Monitor profile Monitor profiles are enabled in the Display properties: 1. Open the Display properties dialog either via the Control Panel or by right clicking somewhere on the desktop area. 2. Select the last tab, named Settings. 3. On this tab click on the Advanced button to open the advanced monitor properties dialog. 4. On this dialog select the tab named Color Management. This is where the ICM profiles for this particular device are listed. 5. Click the Add button to add the profile you installed in section 3.2. 6. When the profile appears in the list it is associated with this device and ready to be used with the ICM Engine.
3.3.2. Printer profile Printer profiles are enabled in the Printer properties of the printer driver: 1. Open the printer properties dialog by right clicking on a printer and selecting Properties. 2. On this dialog select the tab named Color Management. This is where the ICM profiles for this particular device are listed. 3. Click the Add button to add the profile you installed in section 3.2. 4. When the profile appears in the list it is associated with this device and ready to be used with the ICM Engine.
3.4.
Configuring the printer driver
In many printer drivers you have the possibility to enable ICM colour matching. Make sure that these matching settings are OFF in your printer driver to prevent colour matching correction performed twice, namely once by the NedGraphics application and once by the printer driver itself. To turn this setting off, please consult the manual of your printer.
3.5.
Configuring the Engine
3.5.1. Selecting profiles Before you can select ICM profiles in the ICM Engine, they need to be installed. For installation instructions see section 3.2.
3.5.2. Rendering intent The rendering intent is the method the engines use when mapping out of gamut colours back into gamut. This way you can control what happens with colours you can see on your monitor but your printer is unable to print. There are four options available: Absolute Colorimetric The Absolute Colorimetric rendering does not expand or compress the whole gamut. If a colour exists in the printer gamut it is not changed. Otherwise, it is transformed into the closest colour at the gamut boundary. •
Colours that both fall into gamut of the monitor and the printer are not touched by the engine. These are printed as you see them on the monitor.
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Colour Management •
Colours showing correctly on the monitor but which are out of the printer gamut are mapped back into gamut to the closest match the printer is able to produce.
•
The white point is not changed
Relative Colorimetric The Relative Colorimetric rendering produces an exact colour match in everything but brightness, which may be modified so that all the brightness levels are within the range of brightness of the printer gamut. With relative colorimetric rendering, the source white point is converted into the destination white. All other colours are shifted accordingly. The resulting image may be lighter or darker than the original, but the white areas will coincide. •
All colours are mapped back into gamut to the closest match the printer is able to produce.
•
If the white point from your monitor differs from the white point of your printer, the white point of all colours is shifted to the white point of the printer.
•
The white point might be changed
Perceptual If the image has photographic or realistic content and one or more colours cannot be printed, all colours will be compressed into the printer gamut while keeping the relative chromatic positions of individual colours. In this case it is not acceptable that some of the colours might be exactly reproduced whilst others are only an approximate. All the colours, even those falling within the printer gamut, are to be altered in such a way to maintain their overall relationships. Typical this rendering desaturates all colours. When looking at the printed result, the eye will be able to compensate for the difference in saturation between the image on the monitor and the printed one. Saturation Saturation rendering preserves the saturation of the colours in the transformation from monitor to printer, perhaps at the cost of brightness and hue. A typical use for this intent is that of statistical graphs, where it is more important that the colours are bright and saturated, than that they are exactly the same as the original.
3.6.
Selecting the application printer
If the currently selected application printer is not configured properly in the colour management setup dialog, the following warning will appear on application start up: Colour engine 'ICM Engine' could not be created for the selected printer '(your printer)'. Go to File -> Print Setup to select another printer, or go to Tools -> Colour Management to configure the colour settings. The Standard colour engine will now be used instead. In order to display accurate colours for your printer, the colour engine uses the currently selected printer from your application. This printer can be changed in the Print Setup dialog from the File menu. Be aware that a black and white printer cannot have any ICM profiles associated and therefore cannot be used in combination with the ICM Engine.
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Colour Management 4.
T HIRD
PARTY PROFILING SOFTWARE
NedGraphics only delivers you the tool for using ICM profiles, namely the ICM Engine. The quality of the results the engine produces solely depends on the quality of the profiles being used. For the creation of profiles third party profiling software is needed. There are several suppliers available; the ones listed here are known to deliver good results. Bear in mind that this is just an alphabetically sorted list which is not complete and contains only suggestions.
Manufacturer Eye-One GretagMacbeth Monaco Systems
Website www.i1color.com www.gretagmacbeth.com www.monacosys.com
Praxisoft
www.praxisoft.com
Suitable products • Eye-One Publish • ProfileMaker Pro • MonacoEZColor • MonacoPROOF • MonacoPROFILER • WiziWYG
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Colour Management 5.
G LOSSARY
Calibrate, calibration Calibration is the process of measuring the actual output that a certain device produces, and using those measurements to acquire accurate colour representation. A calibrated device is a device which is used in combination with a custom made calibration profile. Colour Management System, CMS A system (process) to manage the way colours are exchanged between two or more different devices. Colour management dialog The NedGraphics dialog which enabled the configuration of all system wide colour management settings, used by all NedGraphics applications. Gamut The gamut of a device specifies the range of colours this device can produce. Colours which are not in this range, and therefore cannot be reproduced by this device, are out-of-gamut. In order to produce the colour anyway, a certain method of changing the colour back into gamut is needed. ICM Engine The NedGraphics colour engine available for all NedGraphics applications. The engine supports the ICM standard, opening the possibility to use proven 3rd party tools enabling accurate calibration of devices. Image Color Management, ICM International Color Consortium, ICC The International Color Consortium was established in 1993 by eight industry vendors for the purpose of creating, promoting and encouraging the standardization and evolution of an open, vendor-neutral, cross-platform colour management system architecture and components. The outcome of this co-operation was the development of the ICC profile specification. ICM Profile, ICC Profile A profile for the ICC standard. The terms ICM and ICC are used interchangeably. NedGraphics Engine A colour engine used in some NedGraphics applications. This engine is custom and does not support the ICM standard. Out-of-gamut See Gamut Profile A profile is a separate file containing information about the colour characteristics of a device. rd A profile can be created by measuring the output of a device, using 3 party software. When creating profiles for a printer, one should create a different profile for each configuration, including variance in resolution (DPI), paper type (matt, glossy) and ink type. Proofing Proofing of printer colours on your monitor shows the actual colours your printer will produce on paper, but showing on your monitor. The results highly depend on the quality of the selected profile.
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Colour Management Render intent When out-of-gamut colours are mapped back into gamut, the render intent determines the way this is done. The ICM standard and Microsoft have different naming conventions for the same intents. ICM render intent Absolute Colorimetric Relative Colorimetric Perceptual Saturation
Microsoft name Match Proof Pictures Graphics
Standard Engine The NedGraphics colour engine which is always installed and used when no other engine is available, such as the ICM Engine. White point The white point of a device is the brightest colour (whitest white) the device can produce.
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