Monitor Calibration & Profiling

Color Vision Logo

PhotoCAL and OptiCAL

By Ian Lyons



A Computer Darkroom Review


7 December 2002


As most of us know by now Photoshop gets all of its information about the monitor from an ICC profile. Obviously the ICC profile must accurately describe "our" monitor before we can even begin to believe that what we see on the screen is accurate. However, in order that we can create such an ICC profile it is necessary for us to use the specialist tools designed for the purpose. Typically such tools will include purpose-designed hardware and/or software.



Since the introduction of the MC-7 colorimeter towards the end of 1999 ColorVision has become synonymous with high quality yet affordable monitor calibration and profiling. However, before getting down to discussing the hardware and software options available from ColorVision it's worth spending few moments reviewing why we should even bother to use them.

So what are these software and hardware tools actually doing? I'm sure your reply will be along the lines - "to calibrate the monitor, stupid". If that was your reply then I'm sorry to say you are only partially correct. Let me explain!

"Calibration" is actually the process of setting a device (in our case the monitor) to a known or fixed behaviour/state. One example being gamma 2.2 at a white point of 6500K. But that's it, calibrating the monitor doesn't say anything about the monitors "actual" capability in terms of what colours it can or cannot display. Every monitor is unique, so consistent colour from monitor-to-monitor cannot be achieved by calibration alone.

In order that we may determine a monitor's actual colour handling capability it is necessary to "Characterise" or "Profile" the monitor. To characterise the monitor we measure and record a range of colours. The data recorded is then saved as an ICC profile, which describes the colour capabilities of the monitor. Once we have characterised our monitor we can use it too its maximum potential.

Adobe provide a tool with Photoshop that enables the above processes to be carried out, and in the main many will find "Adobe Gamma" to be more than sufficient for their needs. Nevertheless, the human eye isn't exactly the most accurate measuring device, and is especially dependent upon stable ambient lighting conditions. A much better option would be to use software that allowed a hardware device to be used for measuring, and this is were ColorVision's PhotoCAL 2.x  and OptiCAL 3.x come in.

Monitor Spyder

The original monitor Spyder was announced at Seybold San Francisco in late August 2000 and was the replacement for very popular MC-7 colorimeter. The one I used for this review arrived in mid November 2000 and boy is it different from the MC-7 that I had already been using. Appearances mean little, although my first thoughts were, if this device works as well as it looks; then heaven help the opposition.




The Spyder colorimeter is a LOT faster than its predecessor, and due to a completely redesigned underbelly (rubber skirt) it's supposedly no longer susceptible to the ingress of ambient light to the sensor window. The MC-7 worked best in a darkened room or when the sensor was covered during the measuring process. I think that even with the new design there may still be merit in doing this, there's really no point in taking chances. However, my own experience would suggest that the Spyder's susceptibility to light ingress is no worse than any other model of monitor calibrator I've used, and is certainly NOT the fault of the new design. From a technical standpoint the Spyder colorimeter uses 8 silicon photo detectors made up of 7 filtered sensors and 1 neutral luminance sensor. It uses the now common Universal Serial Bus (USB) so compatibility with most modern PC's and Mac's is assured.

One important point regarding the original Spyder is that it is not suitable for use with LCD type displays, however this has recently been rectified.

December 2001

A new version of the Spyder was announced by ColorVision at Seybold San Francisco in September 2001. This new Spyder unit has been designed for use with both CRT and LCD type displays. Both PhotoCAL and OptiCAL have been updated  to include the facilities required to calibrate LCD type displays. The screenshots used throughout this review have been updated to reflect the new software versions, however, as at time of writing this update I have not had the opportunity to evaluate the new Spyder.

May 2002

My new LCD type Spyder arrived April and after a few weeks testing it on both LCD (Apple Cinema display and CRT) I can report that ColorVision certainly seem to have cracked the LCD calibration nut. The new Spyder comes complete with a weighted hanger arranged specially designed to suspend the device over the face of the LCD. It is also worth pointing out that the filter attached to the underside of the Spyder MUST be removed when calibrating CRT type displays. This may appear to be a statement of the obvious, but sadly it appears not to have been obvious to some users.


Part 1 - PhotoCal 2.x

PhotoCal is the less expensive of the two monitor calibration/profiling packages available from ColorVision. The version discussed below includes the software and Spyder colorimeter at $174, although an LCD/CRT version can also be purchased at $284.

PhotoCAL is compatible with both the PC and Mac platforms. Users of Microsoft Windows 98/98SE/Me, 2000 and XP should find that it runs with out any problems.

The program itself is quite easy to install and runs via a simple wizard process, much like Adobe Gamma. Each stage is fully explained in the Wizard window and further instructions are provided in the form of a "PDF User Manual". Do make sure the Spyder colorimeter is connected before beginning the process of calibration and profiling.

The Spyder colorimeter is the key to making an accurate profile for the monitor. This device is quite compact and "sticks" to the face of the screen using three suction cups. The user should ensure that the surface of the monitor is cleaned before beginning calibration. The LCD version uses a special harness to suspend the Spyder over the face of the display and so avoids the suction cups damaging the surface.

The screenshots used below are based on the PC Windows version of PhotoCAL, but the process is virtually identical on the Mac. If there is any difference in operation I have not yet seen it. However, one thing to be careful of, make sure that you have disabled the Adobe Gamma  "Extension" on the Mac or remove Adobe Gamma Loader.Exe from the Windows Startup folder on the PC (use the Explorer search facility to search out instances of this file on Windows 2000 systems).



Let me intro........................!


Step 1

Having introduced the LCD/CRT version of the Spyder ColorVision has also revamped PhotoCAL. On startup PhotoCAL 2.7 will ask the user to decide upon the monitor type, e.g. CRT or LCD. The screenshots used below are all based upon a conventional CRT type monitor. If the user makes the wrong selection the software will provide a warning to that effect upon carrying out the luminance measurements, of which more in a moment.


Monitor Type

Selecting the Monitor Type


Step 2

Having selected the appropriate type of monitor we begin the serious work of profiling it. Selecting the gamma is pretty simple, although we shouldn't assume that we must choose gamma 1.8 for a Mac and 2.2 for the PC. Read the user manual and screen tips for further information on choosing the optimum gamma. Mac users choosing gamma 2.2 will probably notice that the desktop and icons appear quite contrasty. If you're calibrating an Apple LCD type display I recommend that you choose 2.2 as this is closer to the Native gamma for Apple LCD's than 1.8.




Step 3

In this step the user chooses their preferred colour temperature. Generally whether using a PC or Mac it's now common practice to use 6500K. This setting provides a slightly cooler or blue white than the old standard of 5000K. Apple LCD users should choose 6500K as this is the value to which most high-end LCD's have been preset.



Step 4

Adjust the CRT monitor contrast to its maximum value; however, be prepared to return to this step if the measured luminance value exceeds the optimum of 95 cd/m2. Actual measurement of the White luminance value takes place at Step 6 below. Setting the white luminance value too high will shorten the life of your CRT type monitor. With LCD type displays the white luminance value can be MUCH higher without any detrimental effect. Apple LCD displays only allow adjustment of the Brightness control which actually works like a Contrast control on CRT displays - set it to around 50% (Apple default value).


Contrast Setting



Step 5

As with Adobe Gamma it's still necessary to make your brightness control adjustment by eye. However, PhotoCAL uses 4 black patches, it's only when all four are just visible that you can tell the system is at the correct level of brightness. I have found this method far easier to work with than the method used by Adobe Gamma and certainly much easier than the methods employed in similar products.


Brightness Control

CRT Only - Adjusting the Black Luminance value


This step determines the Black luminance value and it's especially important with CRT's that it isn't set too low or high. Setting the black luminance level isn't so important if using an LCD type monitor; actually with many it isn't even possible.



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