[UnknownVT]

Rather tangentally, has anyone else viewed black and white chromes projected in a dark room and "seen" color in them? Or looked at a black and white print, and "known" what color a particular object was.

While film/sensor has difficulty reproducing a color that isn't there, I'm wondering if it matters to the final viewing anyway ... So I can look at a red car under a HPS streetlight and it will be gray, or I can photograph it and it will be gray. But when you reintroduce the human element and I perceive the photograph, won't any processing/interpolation that I would have done "live" also happen when I view the reproduction?

I'm not too sure I've fully understood what you are asking -
but seems like it may be about panchromatic representation of colors with greyscale photographs -

In which case, you might want to check out -

Panchromatic Film at Wikipedia

[falconeye]

Have people noticed that fluorescent lighting doesn't seem to that unpleasant anymore - with the popularity of energy saving of CFL (compact fluorescent lighting) spirals -
one can get CFLs at 2700K (soft white), 6500K (daylight) and more recently 5000K (sunlight) and even 4100K (cool white) now from GE - which means they are now in the mainstream.

You speak.

In the EU, you even cannot buy anymore tungsten light bulbs. They have been forbidden!! Next time you visit Europe, bring some tungsten bulbs

[Ben_Edict]

Rather tangentally, has anyone else viewed black and white chromes projected in a dark room and "seen" color in them? Or looked at a black and white print, and "known" what color a particular object was.

While film/sensor has difficulty reproducing a color that isn't there, I'm wondering if it matters to the final viewing anyway ... So I can look at a red car under a HPS streetlight and it will be gray, or I can photograph it and it will be gray. But when you reintroduce the human element and I perceive the photograph, won't any processing/interpolation that I would have done "live" also happen when I view the reproduction?

Yes, many people (myself included) can recognize reds quite easily on bw images, at least photographic prints (not so sure about images in printes books etc.). Other colours are obvious (sky blues), but do not "jump" into the eye, as red does. I guess its versy individual though.

Ben

[Ben_Edict]

You speak.

In the EU, you even cannot buy anymore tungsten light bulbs. They have been forbidden!! Next time you visit Europe, bring some tungsten bulbs

Only certain types have been abolished, those which are considered to be the most energy inefficient ones.

I have been installing full spectrum energy safer bulbs for years in my office ceiling and all my desk lamps, which are virtually indistuinguishable from daylight. And the current generation of Philips daylight balanced energy safers is also astonishingly good and even accepted by my partner to create a general illumination in the house. That is a far cry from the first generations of these energy safer bulbs.

Ben

[Marc Sabatella]

Yes, many people (myself included) can recognize reds quite easily on bw images, at least photographic prints (not so sure about images in printes books etc.). Other colours are obvious (sky blues), but do not "jump" into the eye, as red does. I guess its versy individual though.

We had a B&W TV during my childhood. It was *years* before I happened to catch an episode of Gilligan's Island on a color TV and suddenly realized Ginger was a redhead.

[UnknownVT]

I have been installing full spectrum energy safer bulbs for years in my office ceiling and all my desk lamps, which are virtually indistuinguishable from daylight. And the current generation of Philips daylight balanced energy safers is also astonishingly good and even accepted by my partner to create a general illumination in the house. That is a far cry from the first generations of these energy safer bulbs.

It would appear that Germany is much more forward thinking and energy conscious than the USA, and probably the rest of the world.

I was in the UK in November (only 4 months ago) and the majority of the lights I saw were still regular incandescent/tungsten - or if CFLs were used I didn't notice - perhaps they were using 2700K CFLs?

"Energy Star" CFL's have only recently started to catch on here in the USA -
but many still use the regular incandescent/tungsten light bulbs.

It stands to some reason where a 4 pack of regular GE soft white tungsten light bulbs would cost under $2
- whereas a single CFL would be 1-3x that price -
even though the running cost savings will eventually favor the CFL -
a lot of people still buy on purchase price alone.

When you say daylight bulbs are these fluorescent,
and what is the color temperature please?

In the USA Philips Energy Saver CFLs - only 2700K soft whites are common.

[Ben_Edict]

It would appear that Germany is much more forward thinking and energy conscious than the USA, and probably the rest of the world.

I was in the UK in November (only 4 months ago) and the majority of the lights I saw were still regular incandescent/tungsten - or if CFLs were used I didn't notice - perhaps they were using 2700K CFLs?

"Energy Star" CFL's have only recently started to catch on here in the USA -
but many still use the regular incandescent/tungsten light bulbs.

It stands to some reason where a 4 pack of regular GE soft white tungsten light bulbs would cost under $2
- whereas a single CFL would be 1-3x that price -
even though the running cost savings will eventually favor the CFL -
a lot of people still buy on purchase price alone.

When you say daylight bulbs are these fluorescent,
and what is the color temperature please?

In the USA Philips Energy Saver CFLs - only 2700K soft whites are common.

The Philips Daylight CFL is available in different wattages. An example data sheet is here, though it is very short on specs: http://www.p4c.philips.com/files/8/871016321154110/871016321154110_pss_aen.pdf . These give a nice background illumination and do not have that "aggressive" light quality, often found in older CFLs. They are also fairly cheap. So far, they even proved to be quite reliable.

In my office I use mainly Osram Lumilux Deluxe or Osram Biolux as CFLs or standard tubes. Biolux is full spectrum with an extended UV output (OSRAM|Professionals|General Lighting|Fluorescent lamps|Products|T8|Special lamps T8|index) which is the main difference compared to the Lumilux Deluxe (without the extended UV). These are also used in colour proofing stations. Osram has some nice literature on these light sources: OSRAM|Professionals|General Lighting|Fluorescent lamps|Products|T8|Special lamps T8|LUMILUX COLOR proof T8|index (scroll down to the list of PDFs docs).

Colour Rendering Index is 98! and the spectrum is very comparable to the standard midday natural light.

Ofcourse it is not quite as easy, even over here, to convince people to buy the more expensive CFLs. But European legislation phases out all the old incandescent bulbs, so consumers are forced to go that route. There has been a lot of discussion, as ofcourse the CFLs have a noticeable electromagnetic field and some "experts" came onto the scene to explain, how dangerous that would be. They failed to notice, that you usually do not wear CFLs as a headwear…

Ben

[falconeye]

The Philips Daylight CFL [...]
Osram Lumilux Deluxe or Osram Biolux [...]
But European legislation phases out all the old incandescent bulbs, so consumers are forced to go that route.

Ben, you seem to be more knowledgeable about all this than me, so let me ask you a question:

What is a good replacement for an incandescent bulb which is meant to only be used for a couple of seconds, like a doorstep lamp?

I do have a problem with CFLs (power on slowly) and AFAIK halogen bulbs are soon to be phased out as well.

I tried a "Liquid LED" which replaces incandescent bulbs at only 10% of power consumption and is instant on and dimmable. But I didn't like its light. Must have a bad CRI...

liquid LED ::: Die Original-Energiesparlampe aus dem Bayer-Kreuz in Leverkusen

Overall, CFLs don't seem to be a good solution. Their CRI may be good now, but they power on slowly (no instant on and 1/2 light over first 90s) and they can loose nearly half of their luminance power over the first 2000h. I would have preferred a tax for incandescent bulbs which goes into better alternatives made in the E.U.
Ben, you may find this document to contain interesting bits: http://www.liquid-led.de/liquid_led/vergleich/led%20vs.%20energiesparlampe/oekotest.pdf.

On the other hand, the ban on non-energy saving bulbs in Europe is expected to save 39.000.000.000 kWh per year or 17 million tons of CO2.

[Ben_Edict]

Ben, you seem to be more knowledgeable about all this than me, so let me ask you a question:

What is a good replacement for an incandescent bulb which is meant to only be used for a couple of seconds, like a doorstep lamp?

I do have a problem with CFLs (power on slowly) and AFAIK halogen bulbs are soon to be phased out as well.

I tried a "Liquid LED" which replaces incandescent bulbs at only 10% of power consumption (only 50% of CFLs and over time, cheaper than CFLs) and is instant on. But I didn't like its light. Must have a bad CRI...

liquid LED ::: Die Original-Energiesparlampe aus dem Bayer-Kreuz in Leverkusen

That's a hard to solve problem at the moment. For these short but often repeated cycles, I still think, the good old incandescent bulb is your best bet. Very good bulbs are the shock-resistant types, which have a very long life expectancy and are still available: Glühlampen mit Stoßfestigkeit von Osram bei Westfalia Versand Deutschland

Halogen bulbs, in my experience have a very short lifetime, if switched frequently. There are some CFLs advertised especially for this purpose, but they work best, if any single switch cycle is at least 90s-120s long, which might be unnecessary. Also, I do really not know, how long such a CFL will survive in real use. I would in any case try an Osram modell, especially made for staircases: OSRAM DULUX® EL FACILITY - OSRAM - Voltimum.de

This modell at least looks promising, but I really don't know, how long it would survive, if power cycles are very short. In a typical staircase the power-on cycle would ly within the minimum time frame I suggested or even be a bit longer (depending on the number of floors). So it would be unnecessarily long for the door of a standard family home.

Longevity is probably the reason, why Osram also sells a servo CFL for continous lighting during the dark hours: OSRAM|Professionals|Allgemeinbeleuchtung|Kompaktleuchtstofflampen|Produkte|Intelligente Kompaktleuchtstofflampen|OSRAM DULUX INTELLIGENT SENSOR|index - But a warm white colour will also leave a lot to be desired in terms of CRI. But that contradicts the energy saving efforts somewhat, to have it burn all night…

I would try one of the currently new 3W LED-bulbs (Osram or Philips, not sure), which are available in warm or cool white. But they seem to have a narrow beam and won't illuminate an whole front door, unless you combine several. I am currently trying LED lights in my home, but I must say, I find the light also quite unpleasant, or too dim, to be really useful yet. I have not tried the led bulbs which illuminate the full 360 degs, yet. Just the rated wattage seems to be way too low to be useful - and the water cooled variety you have already tried.

Ben

[falconeye]

That's a hard to solve problem at the moment.

Thanks for your detailed response. Much appreciated.

I found some additional data for the Liquid LED E27 standard bulbs:

Volts: 230V
Beam Angle: 360°
Power Consumption: 4W
Color temperature: 6000°K / 3000°K
Luminosity (lumen): 200 lm / 150 lm
Efficiency: 50 lm/W / 38 lm/W (about CCFL (55), not better)
Color rendition index CRI: 75

(To replace an old 100W incandescent bulb (15 lm/W) with the warm type, one would need 10 Liquid LEDs costing $300 ...)

(I tried a slightly different type, 3300°K and 5W -- but 24W-60W types and with better CRI are needed)


EDIT:
Update, I not only found that a CRI of 75 is rather poor (Color Rendering Index), I also found that the CRI may not be appropriate to describe white LED lamps -> Visual Colour-rendering experiments
BTW, did you know that CRI was introduced with the advent of deLuxe type fluorescent lamps? Maybe, the advent of white LED lamps will create a better index.

[Ben_Edict]

Thanks for your detailed response. Much appreciated.

I found some additional data for the Liquid LED E27 standard bulbs:

Volts: 230V
Beam Angle: 360°
Power Consumption: 4W
Color temperature: 6000°K / 3000°K
Luminosity (lumen): 200 lm / 150 lm
Efficiency: 50 lm/W / 38 lm/W (about CCFL (55), not better)
Color rendition index CRI: 75

(To replace an old 100W incandescent bulb (15 lm/W) with the warm type, one would need 10 Liquid LEDs costing $300 ...)

(I tried a slightly different type, 3300°K and 5W -- but 24W-60W types and with better CRI are needed)

Seems to mirror my own experience. Currently LEDs are good for torches or specialist applications, but not the first choice for household use.

Ben

[UnknownVT]

Seems to mirror my own experience. Currently LEDs are good for torches or specialist applications, but not the first choice for household use.

As mentioned white LEDs have on average CRI=70 which is pretty poor worse than the average for consumer CFL (compact fluorescent) CRI=82.

However white LEDs seem better than CRI=70 (by how much I do not know) -
the CRI=70 I think is even when CIE recommend using the Macbeth ColorChecker chart for measuring CRI -
which is photography friendly and relevant -
being the photo industry standard color chart.

However the US government has a paper out on CRI measurements for white LEDs -

pdf Color Rendering Index and LEDs

For fluorescent - phosphor tuning is the way to improve the spectrum output thus CRI - there are photo grade fluorescent that do have CRI in the 90's, and as you've mentioned in Germany there's one that's even rated CRI=98 - which is unbelievable for a fluorescent.

LEDs still have a ways to go although improvements are coming since their spectrum is also done by phosphor tuning - however the improvement direction has been two fold and I think the efficiency/brightness has been taking most of the initial effort to get white LEDs that are bright and efficient enough.

Now hopefully they'll concentrate on getting better spectrum and higher CRI albeit a different way of measuring them.

Although I would hate to see a CRI=70 white LED become a CRI>=95 just because it is measured differently -
because it won't fool my camera, and probably over the long run my eyes either.

[falconeye]

pdf Color Rendering Index and LEDs

Thanks for the source and they seem to want to make life easier for LED products.

However, this wasn't the general idea I got from the publication I linked above.

It would be interesting to know the content of the CIE 177 report by TC 1-62 ("Colour rendering of White LED Light Sources" ISBN 978 3 901906 57 2), the task force in charge and officially cited by the comission of the EU.

I only found $50 copies ...

[UnknownVT]

Thanks for the source and they seem to want to make life easier for LED products.

Yep, that's why I said:

"Although I would hate to see a CRI=70 white LED become a CRI>=95 just because it is measured differently -
because it won't fool my camera, and probably over the long run my eyes either. "

However, this wasn't the general idea I got from the publication I linked above.
It would be interesting to know the content of the reports of CIE TC 1-62 ("Colour rendering of White LED Light Sources" ISBN 978 3 901906 57 2), the task force in charge and officially cited by the comission of the EU.

Looking for that CIE TC 1-62 paper I came across these:

Labsphere
" What is the TC 1-62 Colour Rendering of White LEDs?

The present color rendering system gives a poor rating for white LEDs yet the color appearance of white LEDs is better than color rendering index would suggest. This is a potential barrier to introduction of white LEDs into main stream applications so TC 1-62 was established to investigate, by visual experiments, color rendering properties of white LED light sources and to test the applicability of the CIE color rendering index to white LEDs. "

Then -
pdf VISUAL OBSERVATION OF COLOUR RENDERING
from Colour and Multimedia Laboratory of the University of Veszprém, Hungary
(the same people as your link)
the visual experiments look very interesting -
their comments on the 4000K tests

" As can be seen, there are huge differences in ordering the lamps according to visual or calculated colour difference. The exceptionally good visual performance of the traditional Cool White lamp is hard to understand, one reason might be that most of the test samples contained only very little long wave radiation. It is also of interest that the small peak wavelength difference between the two clusters produced a large difference in Ra. The rank order for the 6500 K series is the same for all four methods of evaluation. "

I am not too sure if they have taken into account the human eye/brain behavior with different light levels -
as shown in the Kruithof curve -
could this have any bearing on their 4000K results?

I also accidentally came across this
pdf Improving Color Rendering Assessment of Sources: International ...
which seems pretty relevant to our drawn out discussion previously.

It appears to be a pdf of a slide presentation?



This is showing there is obviously a big difference between "white" made up of discrete yellow and blue LEDs and a full continuous spectrum white (like noon daylight).

EDIT to ADD -

I also came across this
pdf Microsoft PowerPoint - LED Test and Measurement Standards
from the NCTU and University of Bath -


note the problems of narrow band RGB sources which was what our discussion was all about....
and then the two direction of the "warm white" LEDs brighter with lower CRI and higher CRI with lower brightness.

[falconeye]

Looking for that CIE TC 1-62 paper I came across these:

Labsphere
" [I]What is the TC 1-62 Colour Rendering of White LEDs?

I think reports as "CIE 177 report by TC 1-62" cited by discussions leading to future legislation or standardization should be made publicly available. They want 50$ from me to get a PDF

Thanks to your link, we now know this at least:

The present color rendering system gives a poor rating for white LEDs yet the color appearance of white LEDs is better than color rendering index would suggest. This is a potential barrier to introduction of white LEDs into main stream applications so TC 1-62 was established to investigate, by visual experiments, color rendering properties of white LED light sources and to test the applicability of the CIE color rendering index to white LEDs.

This does indeed indicate that politics wants to decrease quality standards