BACKGROUND
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.
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).
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.
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.
Step 6
Adjusting the white luminance value for a CRT monitor is critical
to good calibration. In Step 4 we were advised to set the contrast
control to maximum. This step provides us with numerical feedback on
the actual luminance value of the monitor corresponding to the contrast
control setting. Many new monitors will have a maximum luminance value
well in excess of 100 cd/m2. Reducing
the contrast will reduce the White luminance value and is likely to be a lot
easier than ColorVision's instructions (see my notes on the following
screenshot).
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CRT Only |
Step 7
Pre-calibration is the feature that sets PhotoCAL apart. With this
feature we can maximise our monitors colour rendering potential by
getting the colour temperature of the monitor to the desired target
value right at the outset of the process. This will mean that the
profile will NOT need to make any significant correction for white point colour
temperature.
If the monitor allows separate adjustment of the RGB guns for
colour temperature pick the first option. This facility isn't
available on many low cost monitors, but the user should check anyway.
Typically we will find that the monitor has at the very least got presets
for 5000K, 6500K and 9300K. It would be rare to find a modern
monitor (at any price point) that didn't have some means of adjusting
the colour temperature.
If using profiling an LCD that has no controls for White Point, etc
(e.g. Apple LCD) choose "Has no colour
controls".
Step 8
The process of measuring how the monitor
displays red, green, and blue is automatic and takes a few of minutes.
If the monitor allows individual adjustment of the RGB guns then
the dialog shown below will appear.
I use a Mitsubishi Diamond monitor and it has a continuously
adjustable colour temperature control therefore my monitor falls under
option 1. With Option 1 the monitor white point colour temperature is adjusted by
reducing the Red, Green or Blue guns until the 3 coloured bars lie
within the rectangle and the screen luminance
is between 85 and 95 cd/m2. Following
my advice at Step 6 the luminance value should already
have been at the desired value without any need to adjust the RGB guns
for anything other than the colour temperature.
CRT Only
Concluding steps
The remaining steps are automatic; we just sit back and watch.
After a few minutes the user will be asked to name the new profile and that's
it, our monitor is now ready for use. Don't be tempted to readjust
the brightness or contrast, unless you intend to go through the whole
process again.
The remainder of this review relates to ColorVision's more up market
and equally more powerful software package called OptiCAL.
Part 2 - OptiCAL 3.x
Obviously being
aimed at the Professional means that OptiCAL is
intended to be even more accurate than PhotoCAL. It allows the user to
set target values for maximum and minimum luminance, gamma and colour
temperature. Using such an approach should be possible to
match a group of monitors to one standard. But bear in mind that the dimmest
monitor of the batch is the standard to which the others are matched.
I have used OptiCAL on my Mac and PC systems and am extremely happy with
the results obtained. Screen to print matches are good. On the downside OptiCAL is a bit more complex to use
than PhotoCAL. Note that the screen shots and instructions provided below
are specific to calibrating a CRT type display.
In addition to setting our own we can choose from a wide range of
predefined Targets and Curves, each of which describes
the gamma, colour temperature, maximum and minimum luminance levels.
Just so as we're clear what this means, the contrast control of the
monitor determines the white luminance, the brightness control the
black luminance and the colour controls the colour temperature. However, whereas with
PhotoCAL these aim points were
determined by ColorVision; OptiCAL allows the user to set them to any
value they like.
7 December 02
ColorVision have recently updated OptiCAL to version
3.7.x and as part of this update we find the process of
calibrating a CRT monitor has changed slightly. The changes to the
actual application are relatively minor but are still likely to cause
a fair amount of confusion, especially since the user documentation
doesn't really help in identifying the optimum calibration process.
I'll be honest and say that my initial attempts at calibrating a CRT
with this new version were an absolute disaster - so much so that I
almost gave up in disgust. Thankfully I didn't and after a few emails
to smarter folk than me I realised where I was making my mistake.
Rather than try and explain all the possible workflows I have revised
my earlier instructions and so concentrated upon the officially
recommended method of calibrating a CRT monitor.
Pre-calibration of a CRT monitor
The first step in optimising your monitor is Pre-calibration.
Pre-calibration is an optional (I still recommend that you do it) stage with OptiCAL.
To pre-calibrate the monitor we run a small application called PreCAL.
This application enables the user to set the monitor colour temperature to an exact value.
If the monitor is fitted with individual gun control we can also
preset the luminance value. Generally I aim for 90 cd/m2
(because the nice folk at ColorVision suggested it). Initial
indications suggested that I could easily have obtained a luminance
value in excess of 110 cd/m2. However, a lower value can be
achieved by adjusting two of the RGB guns or lowering the contrast control
(never go below 90%). Do NOT use PreCAL
with LCD type displays.
PreCAL - Accurately setting the
monitor colour temperature and luminance value - CRT ONLY!
Profiling a CRT Monitor
Once we open OptiCAL our first activity is to select the
appropriate display type, i.e. CRT or LCD (Step 1). Next we set
our Target values for Gamma and Whitepoint (Steps 2
and 3) - the
Black and White luminance values cannot be changed without first
changing OptiCAL from Standard to Precision mode.
The gamma (Step 2) should be set for 1.8 or 2.2 or whatever value you
prefer. Since we have already pre-calibrated the Whitepoint (Step 3) using
PreCAL we simply choose Native (do NOT be tempted to
choose anything else or you'll undo the PreCAL process). The checkbox
labelled "calibration enabled" should be checked! Once the
gamma and whitepoint values have been selected
we can begin the process of calibrating and characterising the
monitor. ALWAYS use the Calibrate (Step 4) button rather than the
menu options (this was were I came unstuck).
Note:
When configuring OptiCAL we have two basic choices, i.e. Precision
mode or Standard mode - the choices can be made by selecting
Preferences from the File Menu (OptiCAL menu in Mac OS X). Standard
requires that we set the screen brightness by eye as demonstrated in
the left hand screenshot below. Whereas with Precision mode we set
an luminance level and then use feedback from the Spyder to
fine-tune the monitor brightness. ColorVision recommend Standard
mode for most single monitor situations and this is now the route that
I recommend. It is much simpler and less likely to result in confusion
and erroneous results - honest!
Choosing between Standard and
Precision Mode
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Standard Mode (default)
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Precision Mode
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With the Standard mode of calibration the remaining aspects
of the calibration process are fairly straight forward and require no
user intervention other than confirming the ICC profile name. Ideally
you should aim to recalibrate the display at least once per month.
The process of calibrating an LCD is virtually identical except
we choose LCD at Step 1. Since we should never use PreCAL with LCD's we
must define our Whitepoint value. For most LCD's it is better to leave
the Whitepoint at Native and let OptiCAL simply record the value
rather than attempt to adjust it to some pre-defined value.
Extra Features
OptiCAL also includes a useful set of tools that give the
user quite a bit of information on their monitor: -
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Curves - This dialog window is used to display the uncalibrated state
of the monitor, the user selected Target value for Gamma, the
Correction applied to achieve the calibration, and the final
Calibration curve. This information provides feedback on the accuracy
of the calibration and its success in maximizing the range and
brightness of the display.
Looking at the actual curves shown below we can see that the right
most or lower curve relates to the native uncalibrated state of my
Mitsubishi monitor (native gamma of approx 2.2). The curve just to the
left is my target gamma (gamma 1.8) and the left most curve the
correction applied by OptiCAL so that my monitor gamma is corrected to
gamma 1.8. For the sake of clarity, the diagonal line equates to gamma
1.0.
If we turn the Expert Mode ON in the
Preferences we can also use the curves dialog
window to fine tune the profile. This is achieved by adjusting the
control points, we can pick from one, three or nine points depending
upon how accurate we want to be.
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Information - This dialog window provides the user with exact data on the
uncalibrated, target and calibrated monitor. Included is data for
display brightness, in Candelas; White Point (Colour Temperature); Phosphors; The Delta-E deviation of the calibrated monitor's
Colour Temperature, and the Delta-E deviation of the calibrated Red, Green and Blue Gamma
curves from the specified target value.
The documentation (Adobe Acrobat PDF) that comes with the most recent
versions of OptiCAL is only marginally better
than PhotoCAL and nowhere near as comprehensive as it once was.
CONCLUSIONS
Nearly 18 months on from writing the original review we find PhotoCAL and OptiCAL
at version x.7. PhotoCAL has certainly undergone a significant
face-lift and the wizard help messages are even more helpful than
earlier versions. OptiCAL has also undergone a face-lift but not on
the scale of PhotoCAL. In use both programs have been simplified and
reconfigured to enable calibration and profiling of LCD type displays.
As noted earlier the LCD version of PhotoCAL produced very satisfactory results
when calibrating an Apple 22" Cinema display I managed to borrow.
It was equally good with my own 23-inch Apple Cinema HD display.
Using either PhotoCAL or OptiCAL it will take about 5
to 10 minutes to calibrate and
profile CRT monitor from start to finish. This is comparable to most similar products, but on
the positive side is much faster than could be achieved using the
older MC-7 colorimeter. Since LCD's offer less scope for user
adjustment they are calibrated much quicker.
The Spyder/PhotoCAL monitor calibration and profiling
package is one to give serious
consideration too, especially if you're finding it difficult to get a
good screen to print match.
The additional features of OptiCAL will mainly benefit CRT
users working in a professional environment were colour accuracy
across multiple monitors is critical. The facility to set your own
target luminance levels is really quite neat, but probably unnecessary
for most users. I'm sure more expensive
packages offer a similar facility but none of the low end
alternatives, at least not that I'm aware off. OptiCAL also includes hooks for
other devices such as the Sequel Imaging unit, but I don't
think the Sequel unit is in the same league as the Spyder. The much more accurate and
expensive hardware device from X-Rite called the DTP92
can also be used with OptiCAL. In terms of profiling LCD the Spyder is
now competing head on with one of the industries giants - GretagMacbeth.
The LCD Spyder is MUCH less expensive than GretagMacbeth i1
Monitor
but is it any more accurate? I think the Eye-One has the edge but like
many others I believe the Eye-One combined with OptiCAL would
make for a killer package, if only ColorVision were of a similar mind.
