ColorVision Spyder2 Plus Review

Letsgodigital.org
Review of ColorVision Spyder2 Plus
Monitor Calibration Device
http://www.letsgodigital.org/html/re...pyder2_en.html

On Sat, 23 Jul 2005 14:10:58 -0400, "Vince" wrote:

Letsgodigital.org
Review of ColorVision Spyder2 Plus
Monitor Calibration Device
http://www.letsgodigital.org/html/re...pyder2_en.html


Review or press release? or more accurately, "Reviewers' Guide?"
Companies write reviewers' guides for lots of high-tech products to
guide the reviewer in covering all the best features of the product.
The author of this review probably has sore lips from kissing up so
much.

This "review" sure seems like it was written by the company's
marketing people.

I'm really curious as to the reaction of people who already have a
spider-like device. Does this one sound better? What about Monaco's
products? If you spend $1000+ on the system, do you really get better
results than with the $300 systems?

Father Kodak

Father Kodak wrote:
On Sat, 23 Jul 2005 14:10:58 -0400, "Vince" wrote:

Letsgodigital.org
Review of ColorVision Spyder2 Plus
Monitor Calibration Device
http://www.letsgodigital.org/html/re...pyder2_en.html


Review or press release? or more accurately, "Reviewers' Guide?"
Companies write reviewers' guides for lots of high-tech products to
guide the reviewer in covering all the best features of the product.
The author of this review probably has sore lips from kissing up so
much.

This "review" sure seems like it was written by the company's
marketing people.

I'm really curious as to the reaction of people who already have a
spider-like device. Does this one sound better? What about Monaco's
products? If you spend $1000+ on the system, do you really get better
results than with the $300 systems?

If you spend $1000+ you get a spectrophotometer (rather than a
colorimeter) which puts you into another league. As well as increased
accuracy, this gets you printer profiling. But even then, not all
spectrophotometers are equal: some sample every 10nm, some are finer.
Some, however, are more coarse than that, and that's one place where
you have to watch out. To a large extent you get what you pay for.

Andrew.

On Tue, 26 Jul 2005 09:55:44 -0000, Andrew Haley
wrote:


If you spend $1000+ you get a spectrophotometer (rather than a
colorimeter) which puts you into another league. As well as increased
accuracy, this gets you printer profiling. But even then, not all

Can't do printer profiling with this product?
http://www.xritephoto.com/product/ezcolor/

Online price with the colorimeter is $498. From B&H Photo, it is $348
plus shipping:
http://www.bhphotovideo.com/bnh/cont...t& sku=310555

spectrophotometers are equal: some sample every 10nm, some are finer.
Some, however, are more coarse than that, and that's one place where
you have to watch out. To a large extent you get what you pay for.

Andrew.

Pere Kodak

Father Kodak wrote:
On Tue, 26 Jul 2005 09:55:44 -0000, Andrew Haley
wrote:

If you spend $1000+ you get a spectrophotometer (rather than a
colorimeter) which puts you into another league. As well as increased
accuracy, this gets you printer profiling. But even then, not all

Can't do printer profiling with this product?
http://www.xritephoto.com/product/ezcolor/

I guess it's better than nothing. How well this works in practice
depends on the colour matching functions of the three primaries in
your scanner (and the illumination it uses) and the spectral
characteristics of the inks you're using. You might get lucky, or you
might not. The point of a spectrophotometer is to take away the
guesswork.

Andrew.

On Sat, 30 Jul 2005 10:25:14 -0000, Andrew Haley
wrote:

Father Kodak wrote:
On Tue, 26 Jul 2005 09:55:44 -0000, Andrew Haley
wrote:

If you spend $1000+ you get a spectrophotometer (rather than a
colorimeter) which puts you into another league. As well as increased
accuracy, this gets you printer profiling. But even then, not all

Can't do printer profiling with this product?
http://www.xritephoto.com/product/ezcolor/

I guess it's better than nothing. How well this works in practice
depends on the colour matching functions of the three primaries in
your scanner (and the illumination it uses) and the spectral
characteristics of the inks you're using. You might get lucky, or you
might not. The point of a spectrophotometer is to take away the
guesswork.

Andrew.

Andrew,

Can you translate that into English that even a college graduate can
understand?

What is the difference between a spectrophotometer and a colorimeter?
Is that what you are talking about here?

Also, in the "real world", how much better is the color matching from
using a $1000+ unit instead of a $500 unit?

Father Kodak

In article ,
Father Kodak wrote:
On Sat, 30 Jul 2005 10:25:14 -0000, Andrew Haley
wrote:

[ ... ]

I guess it's better than nothing. How well this works in practice
depends on the colour matching functions of the three primaries in
your scanner (and the illumination it uses) and the spectral
characteristics of the inks you're using. You might get lucky, or you
might not. The point of a spectrophotometer is to take away the
guesswork.

[ ... ]

Can you translate that into English that even a college graduate can
understand?

What is the difference between a spectrophotometer and a colorimeter?
Is that what you are talking about here?

Well ... I've only seen research type spectrophotometers, but
I'll have a try.

1) A colorimeter, I would expect, would have photocells measuring
the amount of light through three fairly broad filters,
typically red, green, and blue. All three are measured (and
displayed) at the same time. This can give an approximation of
what is being produced by a screen (or other light source), but
lacks a lot of the details. It's advantages would be that it is
quick to use and inexpensive.

2) A spectrophotometer, however, has a very narrow band filter,
which color is continuously adjustable. A "monochromator" is an
example -- though you don't usually see these outside of R&D
labs, either. You feed light in one end, and take light out the
other end. There is a big knob calibrated in wavelength, and
the wavelength (color) allowed through is selected by internal
diffraction gratings or prisms. (I never got a chance to dig
into one at the lab. :-)

The filter is slowly adjusted through its range, and the amount
of light getting through at each wavelength is either stored for
later display (in a computerized model), or is plotted on a
graph with a drum plotter (in the older examples which I have
observed being used). Note that this must be done slowly,
because the narrow bandwidth of the filter allows very little
light through to the sensor, so it takes time to accumulate
enough information (clear of the noise).

This gives you very fine detail about what is happening to the
light. You will see bright lines from certain emission sources,
or dark lines from absorption by certain things in the optical
path.

They are available in various spectral ranges. I've seen some
which work in the far infrared and in the ultraviolet (both of
those need to have the optical path pumped down to a good vacuum
before running the test, as air absorbs some wavelengths of far
IR and of UV, and may also glow under irradiation with some UV
wavelengths, giving false readings.

The ones for the standard visible range don't have to be run in
a vacuum.

I'm not at all sure how one would build a spectrophotometer to
monitor the output from a CRT or a LCD display.

I would be interested in seeing the spectrum from each of the
"colors" on my LCD display.

Also, in the "real world", how much better is the color matching from
using a $1000+ unit instead of a $500 unit?

As both of these are at least an order of magnitude less
expensive than the spectrophotometers which I have seen, I'll not
attempt to answer here. IIRC, they were made by Nicolet.

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

DoN. Nichols wrote:
In article ,
Father Kodak wrote:
On Sat, 30 Jul 2005 10:25:14 -0000, Andrew Haley
wrote:

[ ... ]

I guess it's better than nothing. How well this works in practice
depends on the colour matching functions of the three primaries in
your scanner (and the illumination it uses) and the spectral
characteristics of the inks you're using. You might get lucky, or
you might not. The point of a spectrophotometer is to take away
the guesswork.

[ ... ]

Can you translate that into English that even a college graduate can
understand?

I guess that depends on the major, but I'll try!

What is the difference between a spectrophotometer and a colorimeter?
Is that what you are talking about here?

Well ... I've only seen research type spectrophotometers, but
I'll have a try.

1) A colorimeter, I would expect, would have photocells measuring
the amount of light through three fairly broad filters,
typically red, green, and blue. All three are measured (and
displayed) at the same time. This can give an approximation of
what is being produced by a screen (or other light source), but
lacks a lot of the details. It's advantages would be that it is
quick to use and inexpensive.

Right. The problem with a colorimeter is that to be accurate it has
to have precisely the same spectral sensitivities as the eye. This
isn't impossible, but it is hard. Flatbed scanners don't have the
same RGB sensitivities as the eye. This means that when you scan two
colours, they might measure the same but they look different to you.
Or, two colours that look the same to you measure different on the
scanner. The other problem with a flatbed scanner is that their
illuminants are often nothing like daylight, and that can cause a
colour shift too.

This is the set of spectral sensitivities for a "typical" observer:
http://hyperphysics.phy-astr.gsu.edu...colcon.html#c1

If you have the full spectrogram, you can match the spectral
sensitivity curves of the eye accurately, and calculate from the
entire set of readings the _true_ RGB values of a sample. If, as with
a scanner, you only have three numbers, and these numbers were not
measured through filters like those of the eye, you can't get an
accurate spectral match.

2) A spectrophotometer, however, has a very narrow band filter,
which color is continuously adjustable.

Modern spectrophotometers as used for printer profiling have an array
of detectors 10nm or so apart, so there is no scan as such: the entire
spectrum is detected in parallel. At least, the decent ones work this
way.

[ good stuff snipped ]

I'm not at all sure how one would build a spectrophotometer to
monitor the output from a CRT or a LCD display.

It's really quite simple: a diffraction grating illuminates a
light-sensitive diode array.

I would be interested in seeing the spectrum from each of the
"colors" on my LCD display.

Also, in the "real world", how much better is the color matching from
using a $1000+ unit instead of a $500 unit?

It all depends on the inks you're using. Some inks have very smooth
spectral curves, and these might work well with simple colorimeter
profiling. Some inks, especially pigment inks, don't.
Colorimeter/scanner based systems might work well with "typical" inks
and papers because that's what they've been calibrated with, but get
less accurate with unusual combinations of inks and papers.

Andrew.

In article ,
Andrew Haley wrote:
DoN. Nichols wrote:

[ ... ]

2) A spectrophotometer, however, has a very narrow band filter,
which color is continuously adjustable.

Modern spectrophotometers as used for printer profiling have an array
of detectors 10nm or so apart, so there is no scan as such: the entire
spectrum is detected in parallel. At least, the decent ones work this
way.

[ good stuff snipped ]

I'm not at all sure how one would build a spectrophotometer to
monitor the output from a CRT or a LCD display.

It's really quite simple: a diffraction grating illuminates a
light-sensitive diode array.

Aha -- a significant improvement -- as long as you aren't
looking for things like absorption or emission lines significantly
narrower than that. I think that sometimes you still have to do it the
slow way, but the system which you describe would certainly speed up a
lot of the operation for most uses.

Thanks for bringing me up to date on this.

Again, thanks,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---