|5.4 Tuning the monitor calibration with Eizo ColorNavigator
|1.1 Viewing room condition
|5.5 Additional fine tuning
|1.2 Viewing monitor condition
|6. Test image for optical soft proof verification
|2. Certified hardware calibrated proof monitor
|7. Cloning multiple monitors to match a master reference monitor
|3. Light box for soft proof verification
|8. Validating the adjustment status of a monitor
|4. Select the printing process
|9. Setup tips for non-light box environments
|5. Monitor ICC profile generation and optimization
|5.1 Setting up the initial monitor calibration with Quato iColorDisplay
|5.2 Tuning the monitor calibration with Quato iColorDisplay
|5.3 Setting up the initial monitor calibration with Eizo ColorNavigator
We'd like to share our experience from the soft proof testing and FograCert soft proof certification. One major characteristic of the Fogra certification is that the complete viewing environment is taken into account instead of measuring directly on the proof monitor screen only (which omits the viewing condition). Fogra uses the Konica Minolta CS-2000 spectroradiometer to measure colors from a viewing distance of about 80 cm, and they compare the soft proof colors against the reference print (or proof) in the viewing light box.
A good starting point to set up your own working soft proof system is an already FograCert certified soft proof solution. Usually, the certified solution includes or specifies a monitor, color measurement devices with profile-making software, proofing software, and a reference “viewing condition”, in this case, a Just Color Communicator 2 light box showing a reference print printed in accordance with the Fogra39 printing process. A Fogra certified solution means that the soft proof was certified with the setup and viewing conditions at Fogra.
This article gives advice on how to get a perfectly matching soft proof which is visually identical with a print or proof within a light box. Once the match is perfect, the resulting calibration values (paperwhite K, x, y and Candela) can be used to set up new soft proof stations matching your reference proofing environment.
For this documentation we give the instructions for Mac OS X computers. However, the same Eizo and Quato profiling applications are identical on Windows, therefore it should be easy to adapt this to Windows. Other operating system related settings should also be easy to adapt to Windows.
The viewing condition highly depends on the light condition within the room. Viewing a print or a soft proof using daylight will highly distort the colors. Important notes are:
Please consider that the proof viewing condition includes the ambient light as well as the monitor backlight and the light box light. A matching soft proof requires a stable light environment which will not distort the viewed result.
In WebShare, create a new “Proof” branding using these these settings:
It is important that the appearance on the monitor is not disturbed by a colorized background or colors in the menu or on the desktop. Also avoid a white desktop because this RGB 100% white will be different compared with simulation white of the printing process. Please also avoid a second monitor next to it with a white or colorized background/content.
There are only a very few hardware calibrated proof monitors available, namely from Quato, Eizo and NEC. Avoid non-specialized soft proof monitors; even wide gamut monitors may not work well because they don't have built-in hardware calibration and the backlight light distribution is not uniform across areas of the screen. We generally recommend using only soft proof monitors that have been certified by Fogra. Steps to prepare a monitor to use for proofing:
Please noteSwitching a monitor profile within the operating system for a hardware calibrated monitor does not work; this must always be done via the vendor's ICC profiling software. This will set the ICC profile in the operating system and download the hardware calibration into the monitor. Usually, the ICC profile for the hardware calibrated monitors just includes a very simple profile specifying the x/y/z values for the RGB colors. The correction tables are downloaded into the monitor and will be applied via the monitor video hardware. The benefit here is that the 256 step increments of each color channel are fully utilized to define colors because most of the calibration is done by the monitor hardware rather than by the ICC profile.
When it is required to compare a proof or print against a soft proof, a stable viewing condition is needed. We use the “Just Color Communicator 2” for this. This light box comes with D50 illumination and offers the possibility to adjust the brightness to the required level. The following steps should be taken for preparation::
Tele-measuring from a distance of 70 cm allows metering the brightness in the middle of the light box, to adjust to 160 Candela. It is important to match the brightness between the light box and the proof monitor by showing an empty (white) page on the monitor simulating the printing process. This can be done with one of the following measurement devices:
or similar devices that can measure the brightness in Candela from a viewer's distance.
In the following, we simply call it tele-measuring.
Please note: Proof monitors will display a very stable white across the entire screen via their built-in area dimming control. The light distribution within the light box is not the same in different areas, therefore placing the reference print/proof into the middle of the light box will give you a better average.
We used the Fogra39 printing process. For the printing simulation we used the ICC profile “ISOcoated_v2_eci.icc”, which implements the Fogra39 standard. Another option would be to use the “US GRACoL2006_Coated1v2.icc” profile which implements the IDEAlliance printing standard. The printing process is determined by an ICC profile and must be specified in the proofing software.
In WebShare this is done via Default Simulation Profile in the “My User Preferences” settings; general print process simulation profiles for all users can also be specified in the WebShare “Server Preferences
This paragraph is the most important section of this guide to get a perfectly matching soft proof. The point is that the initial soft proof monitor profile setup is unlikely to match the print in the light box immediately, therefore multiple passes of tuning including profile generation must be done to get a perfect match.
There are different gamma settings possible. Once chosen, a gamma must be used consistently in the proofing process, because it is included in the calibration and it may be assumed by color editing solutions. In general, different gamma settings of 1.8, 2.2 and L* can be used for proofing, it is up to the customer. All HELIOS proofing certification has been performed using a gamma of 1.8.
|Mac OS 9
|Mac OS X 10.0-10.5
|Mac OS X ab 10.6
Gamma 1.8 was preferred in workflows without color management because a Gamma of 1.8 was matching the output of black and white printers. So far, prepress has also used a Gamma of 1.8 which is now changing to 2.2.
Gamma 2.2 used for modern video formats such as QuickTime H.264. Gamma 2.2 is also used with Mac OS X 10.6 and on Windows.
Gamma L* means the gamma is adjusted so that the L channel from CIELab is always mapped into monitor RGB grayscales, e.g. L30 means all RGB channels are set to 30% (a dark gray) on the monitor. The special feature of L* is that all RGB gray definitions will always represent the natural grayscale.
After step 5.1 has been completed, do the following:
After step 5.3 has been completed, do the following:
Now a new calibration is done and additional iterations of the tuning b) should be performed until the result represents the perfect match. Our experience is that this procedure must be done multiple times until you have a perfect visual match between the light box and the soft proofing solution.
Once you have a perfect match, make sure you write down the x/y/K values of your working settings, these can be applied to additional monitors of the same model/vendor.
In general customers can use their own test images to verify the visual match between the printing process/proof and the soft proof.
To verify the match of the soft proof against the light box check the following:
Whenever the white point or brightness is changed, ensure that you have done a visual verification using your test image.
This task is very simple assuming you use the same monitor model and measurement device for multiple locations/users. The following must be done:
These settings can usually be done in the custom settings of the profiling software
For Quato iColorDisplay, e.g. Select Settings > Advanced Mode, set the luminance to 160 and the K/x/y as described here, and run the calibration.
For Eizo ColorNavigator create a new Target with the specified settings and "Proceed" with the new measurement.
Don't use any tuning because the goal is to replicate the calibration of the reference monitor.
Once the calibration is finished upload the new ICC profile to the WebShare user settings and proofing should match the printing process.
It is required to verify regularly the monitor calibration. The easiest procedure would be to do this always before starting a proofing session. Monitors should be stable for many days, however a validation will document that the current calibration is up to date.
Quato includes the Ugra UDACT profile validation. Eizo's Color Navigator ICC profiling software includes a verification option
This section gives you some sample values for different printing processes. Viewing will be easier if a soft proof is viewed in a dark/gray room (no daylight) because there is no direct print reference and the human eye will quickly adapt the minor white point details. A certified and calibrated proof solution will ensure that the whole system works in general. Then it is merely a question of the appropriate reference settings. Please note that different measurement devices may give slight variations in the color measuring results. Even multiple devices (e.g. X-Rite i1's) of the same vendor will show minor differences.
These are estimated values (with a luminance of 160 cd/m2):
|ICC print profile
Once a matching white-point is developed or specified by a reference soft proof monitor, setting up additional soft proofing workstations is simple and can be done straightforwardly with little work. Using certified solutions provides the confidence that the whole system works.
Using non-certified components (monitors, measurement devices, profiling software, proofing software) will likely fail to provide matching and stable results. The HELIOS WebShare PrintPreview UB2 soft proofing solution has been certified already using six different monitor combinations.
paperwhite K: Kelvin is the color temperature of the white. The ICC uses a reference color temperature called D50 (K5000) which is a little yellow compared to the D65 (K6500) PostScript reference which is more blue. Today's consumer PC monitors have a white which is often very blue D90 (K9000). Coated offset printing paper is somewhere between K5000 and K5300. Print copy paper has usually a blue touch.
CIE x/y comes from the 1931 x/y color position definitions. x defines the horizontal axis and y the vertical axis of the color.
Candela is the base unit of luminous intensity (cd/m2). See http://en.wikipedia.org/wiki/Candela
The HELIOS soft proofing solution is Fogra soft proof certified and works from any Windows or Mac computer using a Web browser and allows remote soft proof with multiple users. It also allows signing-off proofs and discussing the content via annotations between multiple users. The solution includes the HELIOS WebShare UB2 and HELIOS PrintPreview UB2 products. It is a purchased software package and runs on the customer's intranet server. The solution costs about 5,900 Euros for 10 remote users.
Konica Minolta CS-100 is a luminance & color meter, we used it for brightness measuring of the light box and soft proof monitor. The CS-100 costs about 4,500 Euros. The Konica Minolta LS-100 is a luminance only meter which is sufficient to compare the brightness between the light box and the soft proof monitor. The LS-100 costs about 2,300 Euros.
Konica Minolta CS-2000 is a spectroradiometer used for high-end professionals to measure color. The Fogra soft proof certification uses the CS-2000 for technical reference measuring to verify color patches on the light box with the soft proof monitor. The device costs about 25,000 Euros.
X-Rite i1 Pro is a spectral measurement device which supports emissive (monitors) and reflective (print) profiling. The i1 device is directly supported by Quato and Eizo profiling software. X-Rite offers the i1 Basic Pro with and without X-Rite ICC profiling software. For the soft proofing procedure described here we used the i1 Basic Pro revision D without any X-Rite software. The device costs about 800 Euros.
iColorDisplay is the ICC profiling software from Quato which is included with their soft proof monitors.
ColorNavigator is the ICC profiling software from Eizo which is included with their soft proof monitors.
JUST Color Communicator2 is a viewing cabinet (light box) to view printed samples. It supports even illumination at D50 and can adjust the brightness. It is glare- and reflection-free. See also: www.just-normlicht.de