Calibration System



LCD & CRT Displays

By: - Ian Lyons

A Computer Darkroom Feature Preview

There is no doubting that many in the graphics and photographic imaging industry are finding that LCD type displays are more than just pretty desktop furniture. However as they will also tell  us - LCD displays present conventional CRT display calibration systems with a unique set of problems. Such are these problems that many vendors have found it necessary to develop a whole new set of profiling tools.


What is MonacoOPTIX and why is it required?

In concluding my review of MonacoEZcolor I made the following remark "It's a pity that the application doesn't support the calibration of  LCD displays, especially since MonacoEZcolor 2.2 is primarily aimed at Mac users and we all know that Apple are pushing LCD displays with all the marketing hype they can muster." I think someone at Monaco Systems must have reading my review because that shortcoming has now been addressed.

MonacoOPTIX is a new monitor calibration system from the same stable as MonacoEZcolor and is purpose designed to facilitate fast and accurate calibration of LCD and CRT type displays. At its heart we find a brand new dual-purpose colorimeter developed by Sequel Imaging a company renowned for producing good quality display calibration hardware. Conventional colorimeters such as the Sequel Chroma IV as supplied with previous versions of MonacoEZcolor utilise a suction cup arrangement to secure the sensor to the display surface. However, securing the sensor using suction will cause serious damage to the sensitive surface of most LCD's. So instead of attaching the sensor to the LCD we use a soft felt faced attachment and suspend the combination over the display using its own weight to apply sufficient pressure to ensure minimal extraneous light ingress to the sensor cell. The new sensor is supplied with removable components that have been designed to ensure contact between the display surface and the sensor is not liable to cause damage. We also find that the normal sensing cell response for CRT type displays isn't appropriate for LCD's, especially with the luminance range extending well over 200cd/m2. Again Monaco Systems have utilised improved electronics with the aim of providing a colorimeter that is more responsive and accurate than the previous CRT only - MonacoSENSOR.





LCD and CRT attachments

The following summarise the features and Benefits of MonacoOPTIX:

  • The MonacoOPTIX colorimeter utilises intelligent electronics for both LCD and CRT display calibration

  • Patented "Light Tunnel" technology ensures accurate LCD profiles

  • Unique pulse-period timing for accuracy at very low light levels

  • The colorimeter is factory calibrated to National Institute of Standards (NIS) standards

  • Attractive design features including removable components for profiling of LCD and CRT displays

  • Software is intuitive with a wizard-like interface for fast and easy profiling

  • User-selectable white point and gamma settings

  • Hardware-assisted brightness and contrast adjustment for greater accuracy

  • Compatible with Microsoft Windows plus Apple Mac OS9 and OS X

Putting MonacoOPTIX to Work

As with MonacoEZcolor  we find this new application makes extensive use of a wizard-based interface (Figure 1); making it very intuitive and easy to use. As a result, the steps involved in creating a display profile very straightforward.

Integrated on-line help is always available and easy to follow. If you need more help an Adobe Acrobat user guide is installed to the computer hard disk.  The guide even includes chapters on colour management and a short section covering frequently asked questions. Monaco Systems also provide a wealth of information on their web site - http://www.monacosystems.com



At Step 1 we begin the process of building the display profile by choosing between either LCD or CRT. It is important that the correct display type is selected otherwise you'll end up with some surprising calibration options and the resulting profile (assumes you get that far) will not be accurate. Please remember to read the on-line instructions!

The next screenshot shows Step 2, namely fixing the correct attachment. The attachments can be secured released by a simple quarter turn twist. If you're going to make a mistake don't make it at this step - the damage to the surface of your very expensive LCD display may not be repairable.  Also note that with CRT type displays we usually need around 30 minutes before everything is stable; LCD's reach maximum brightness within only a few minutes and so the process of calibration can begin much sooner.


Figure 1

Step 3 shows the options available for the Target White Point (sometimes referred to as the Colour Temperature). Unless you have good reason it's probably better to choose 6500K.Once the target white point has been selected you should adjust the display colour temperature controls to match this value so far as it is possible to do so. It is worth noting that some monitors have RGB gun controls, others have a range of presets and high-end  LCD's typically have no control. You should establish the type of control provided on your display (Apple LCD's have no controls for white point but are instead preset to 6500K) and proceed with the appropriate adjustment.

Step 4 shown on Figure 1 above relates to calibrating the OPTIX sensor itself. This is an important step and involves setting the sensor on the desktop and pressing the calibrate button. The colour of the desktop shouldn't matter - just make sure that no light gets to the sensor cell.

NOTE: the remaining steps describe the process of calibrating a CRT type display!




Display Calibration

Figure 2 shows the main steps involved in calibrating the display. Following the on-line instructions is essential from this point onwards. At Step 5 we are adjusting the CRT Brightness and Contrast controls to 100% (maximum) and measuring the lightest black.

In Step 6 we measure the darkest black and this is achieved by setting the monitor Brightness control to minimum. If your display can't reproduce a dark enough black the software will provide a warning message and give you the option to make a visual adjustment.


Figure 2

Step 7 requires that we adjust the monitor Brightness control so the reading falls within the "Good" (Green) band. Typically this will mean a few attempts at adjusting the brightness value so don't worry if the first attempt fails. Once you have achieved the optimum brightness level it is important not to make any further adjustments otherwise the calibration is void.

Step 8 is the point were MonacoOPTIX determines the colour characteristics of the display by cycling through a series of 33 different coloured patches. Typically this will only take a few minutes and requires no user input.

In Step 9 we choose our preferred profile Gamma. For historic reasons many Mac users tend to choose 1.8 and Windows users 2.2 - Whilst I primarily use Mac OS X I prefer the Windows gamma value of 2.2 If you are using the display for Photoshop it really doesn't matter which gamma is a chosen as Photoshop will make any necessary on-the-fly gamma corrections for you. Once the gamma value has been chosen it simply remains for you to Save the Profile (giving it a unique and meaningful name).


Figure 3



In a sense I'm fortunate to be in the position to test MonocoOPTIX on the full range of supported computer platforms and display types. I am also able to compare MonacoOPTIX with other competing products such as  the DataColor Spyder+PhotoCAL/OptiCAL and GretagMacbeth Eye-One Match; all of which are reviewed elsewhere on this web site. So what do I think and is there scope for improvement?

  • The MonacoOPTIX software application installs easily and works equally well on both Mac and PC platforms; the only observable difference between the Mac and PC is the dialog Header. The USB connection also means that the hardware will be compatible with most recent Macs and PC's.

  • The instructions at each stage of the calibration process are clear and sufficiently detailed to ensure that most users will have no problems getting their display calibrated fairly quickly and with minimal fuss.

Comparison with the Opposition!

  • Unlike GretagMacbeth Eye-One Match and ColorVision Spyder+PhotoCAL/OptiCAL the MonacoOPTIX system lacks facilities for the user to accurately pre-calibrate the display hardware White Point. Whilst this isn't a serious omission it does mean that those users with separate RGB gun control won't be able to take full advantage of these controls.

  • The colour gamut and in particular the chromacity values of the profiles obtained from each of the systems mentioned above shows that MonacoOPTIX profiles compare very favourably with those from the more expensive Eye-One spectrophotometer. Both Spyder bundles appear to produce profiles with different chromacity values, which tend to result in more emphasis on blue/cyan and less on green/reds. My initial impressions having compared how all four systems reproduce a range of images was that they are all equally good. However, a more detailed analysis of each application suggests that MonocoOPTIX is in fact producing very similar profiles to Eye-One, and that these profiles are more accurate than those obtained from either Spyder bundle. The numerical differences might appear small but the effect of the chromacity discrepancy is clearly visible when a digital version of the GretagMacbeth ColorChecker chart is viewed with my Apple Cinema HD Display. The Spyder based profiles have reproduce blue and cyan much stronger, but they aren't an accurate representation of the ColorChecker. The advantage provided by the Apple display for this comparison is the fact that the profiles are all based upon exactly the same display settings (i.e. there is nothing to change so nothing should be different). I repeated the above test with two other Spyders and a Mitsubishi CRT with similar results, which leads me to believe that there is a bug in the current version of both ColorVision applications.

  • Both greyscale and colour gradient tests show that MonacoOPTIX is equally as good as Eye-One Match or PhotoCAL/OptiCAL producing neutral greys with no obvious signs of banding in either greyscale or colour gradients.

  • I'm not convinced that "hanging" the MonacoOPTIX sensor by its own cable is a good idea (my electrical training tells me this may eventually result in tears). Likewise the counter-weight is not securely fixed and mine has fallen off on more than one occasion. Both the Eye-One and Spyder use a superior support harness and weighting arrangement.


Comparing Colour Gamut's for Apple Cinema HD Display

The results of my comparative test show that the MonacoOPTIX is producing more colour accurate profiles than the similarly specified and highly regarded ColorVision options. So leaving aside the few shortcomings identified above I believe that the quality of the display profiles created by the MonacoOPTIX make it well worth considering by anyone in the market for an accurate display calibration system. The ability to calibrate both LCD and CRT type displays makes it a future proof investment and one that will ultimately pay dividends in the form of colour accurate ICC profiles.   Anyone already using and earlier version of MonacoEZcolor and considering the purchase of an LCD display should look no further than MonacoOPTIX or even upgrade to MonacoEZcolor 2.5

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