Color Accuracy Essentials
There are usually three separate elements that influence the quality and color accuracy of a display--the video card driver (software), the video card driving the display, and the display itself. The ColorVision Spyder and the accompanying OptiCAL software first attempts to put the display into a known and well behaved state, proceeds to measure the characteristics of the display in this state, and creates a file which alters (via software) the look-up table of the host computer's video card to correct its output. Finally an ICC profile for the display is generated and saved to the correct folder on the computer. ICC savvy applications such as Adobe Photoshop, Picture Window Pro, Corel Draw, Adobe InDesign, and others can all use custom display profiles, so the benefit of this operation is not strictly limited to use in a single application. Because of the fact that attributes of a display slowly change over time, recalibrating and profiling is not a one-time event. Calibrating and profiling the display at regular intervals becomes the best way to ensure the necessary level of accuracy is maintained over time.

Package Contents And Setup
Delivered in a durable black storage case, the Spyder colorimeter, OptiCAL software CD-ROM, and assorted accessories are well protected from damage. The CD-ROM contains not only the OptiCAL software, but the drivers for the Spyder hardware, as well as the manual in electronic PDF format. After reading the PDF instruction manual that is provided, installing the software on both the Windows and Macintosh platforms was simple and trouble free. It is very important to follow the documentation as there are important steps that need to be taken (such as removing Adobe Gamma from the startup folder in Windows or disabling the Adobe Gamma extension on OS 9) to ensure a successful calibration and profiling session. The documentation also provides very important and specific information on how to physically configure the Spyder for use on an LCD or CRT display. By neglecting to configure the Spyder properly, there is risk of a damaged or ruined LCD panel.

The Spyder is a seven-filter colorimeter, and its function is to compute color matches from measurements of the display surface. The Spyder interfaces to the host computer using a USB connection for both communications and to fulfill its own internal power requirements. Due to the accuracy of the colorimeter in measuring the characteristics of the display, the resultant profile that is generated by OptiCAL will be built with high quality measurement data.

CRT Calibration And Profiling Process
The first machine used in my testing was a Windows 2000 based computer with a conventional CRT display. Before launching the software, I plugged the Spyder colorimeter into a USB port and Windows immediately recognized the device. When working with most CRT displays, there are actually two separate software applications that are used, PreCAL and OptiCAL. PreCAL (Pre-Calibration) allows CRT users to optimize the brightness, contrast, and color temperature settings.

If your particular display has the built-in controls needed to adjust the individual RGB gun output, PreCAL will prove valuable, otherwise skip straight to OptiCAL and bypass PreCAL. The real power of PreCAL is the ability to utilize the Spyder when adjusting the gain of the individual RGB guns in the display, and equalize their output levels at a selected correlated color temperature, in my case 6500Þ Kelvin. The purpose of this procedure is to help correct the behavior of the display using its own built-in color controls, which will ready the display for final calibration and profiling using OptiCAL.

Check the accompanying illustration to see how the Spyder is attached to my CRT display. In the PreCAL application I've balanced the output of the three RGB guns at my target correlated color temperature of 6500Þ Kelvin.

Using OptiCAL
Once finished with the PreCAL application, the user simply launches OptiCAL to perform the balance of the operations. The preferences in OptiCAL allow you to set the frequency at which the recalibration warning is displayed. Because I recalibrate and profile every 30 days, I set the warning period at one month. One month later when I boot my computer, OptiCAL will remind me to recalibrate and profile.

The calibration mode (standard or precision) can also be specified in this window, and the standard setting yields excellent results. The precision mode is not necessarily better--it simply allows the user to specify their own white and black luminance values that they would like to specifically target. Because most users won't know appropriate values to set these values at, ColorVision generally recommends using the standard calibration mode. The option to display "Control Points in Curves Window" is valuable if you want a visual representation of the adjustments made by the calibration and profiling process and the ability to edit or manipulate these results.

Once the preferences were properly set, I specified that I was calibrating a CRT type display, specified a gamma curve of 2.2, and set the whitepoint to "native" because I already set the whitepoint (6500ÞK) previously in the PreCAL application. If my CRT display did not have individual gun controls or I simply bypassed PreCAL all together, I would set the whitepoint at my preferred correlated color temperature of 6500Þ Kelvin. After these settings are complete, clicking the "Calibrate" button activates the automated calibration and profiling process. Following the on-screen instructions, the user attaches the Spyder to the face of the display and waits for OptiCAL to complete the calibration and profiling. Once finished, the Spyder is removed from the display, a dialog box pops up and the user can name the profile, and the profile is saved to the proper directory on the hard drive.

LCD Calibration And Profiling Process
To evaluate the LCD calibration and profiling capabilities of this package, I switched over to my Macintosh running OS X 10.2.4 that is currently connected to a Cornea Systems 17" LCD. While the software interface is identical for each platform, the Spyder colorimeter is altered with two additional pieces when used to calibrate and profile LCD displays. The most critical piece is a honeycomb sled that attaches to the underside of the Spyder. This prevents the suction cups on the body of the Spyder from sticking to the LCD surface. It is also used to alter the luminance entering the sensor in the Spyder so that the LCD technology can be properly calibrated and profiled. The second attachment is a counterweight designed to offset the weight of the Spyder and therefore prevent the Spyder from moving around while taking measurements from the surface of the LCD.

When performing LCD calibration and profiling, the PreCAL application that was used for pre-calibrating CRTs is not used. OptiCAL is the only program needed, and the calibration mode should be set to "standard" as per the instructions. I choose "LCD" as the monitor type, gamma 1.8 (standard system gamma for Macintosh), "native" for the whitepoint, and clicked the "Calibrate" button to begin the operation. Again, I followed the simple on-screen instructions and allowed the software to do its work.

The automated calibration and profiling process for the LCD took just under eight minutes to complete, and once the profile was generated, I named the profile and it was saved to the appropriate directory. It was interesting to look at the Curves Window after the process was complete. It is in this window that you can see the degree of correction required by the calibration and profiling process. The benefit of calibrating and profiling each of the displays I tested was obvious, and clearly leagues ahead in terms of accuracy over programs like Adobe Gamma or the Apple ColorSync utility.

Final Thoughts And Recommendations
The Spyder with OptiCAL package gives the user the ability to create professional display profiles with a minimum of work. I can't overemphasize the importance of display calibration and profiling to photographers. As previously mentioned, there are many imaging applications that are ICC profile aware and therefore can take advantage of custom display profiles created with this software.

For photographers on the fence as to whether this kind of calibration and profiling is necessary, realize that the visual accuracy of images that the user is viewing in Photoshop is entirely dependent on the quality of the display profile. This fact makes having a custom display profile that much more important for photographers who want a truly accurate representation of their digital files.

With a retail price of $299, the costs involved with purchasing this type of package should be easily offset by the reduction in wasted time trying to color correct images on an uncalibrated display. Photographers who outsource their printing to a professional lab or do their printing in-house will benefit from knowing that any color problems are not the result of this particular element in their own color management workflow.

My experience with ColorVision technical support has been very good, and the ColorVision web site has valuable information as well as product updates so that users can always have access to the newest software. For further information on this product, check out the ColorVision web site at www.colorvision.com.