Kodak Unveils Brighter CMOS Color Filters 184
brownsteve writes "Eastman Kodak Co. has unveiled what it says are 'next-generation color filter patterns' designed to more than double the light sensitivity of CMOS or CCD image sensors used in camera phones or digital still cameras. The new color filter system is a departure from the widely used standard Bayer pattern — an arrangement of red, green and blue pixels — also created by Kodak. While building on the Bayer pattern, the new technology adds a 'fourth pixel, which has no pigment on top,' said Michael DeLuca, market segment manager responsible for image sensor solutions at Eastman Kodak. Such 'transparent' pixels — sensitive to all visible wavelengths — are designed to absorb light. DeLuca claimed the invention is 'the next milestone' in digital photography, likening its significance to ISO 400 color film introduced in the mid-1980's."
we had 400 speed reversal film in the 50s (Score:4, Interesting)
I refer you to Tri-X b/w, and to Fujichrome 400 around 1972. a really nicely balanced and warm film. if you pushed it to 1200, you could peel the grains off the base and go bowling with them, but the picture held up remarkably well on the small screen. it was THE go-to magic film for 16mm newsfilm when it came out.
if that was a negative film, it would have been asa 800 with little more grain than the "fast" 125 color film of the time.
Nothing too revolutionary (Score:2, Interesting)
why are sensors in RGB instead of CMY? (Score:3, Interesting)
They divide each sensor of the regular bayer pattern to 4, half white, half color. This way one can also report a 4-fold increase in the number of pixels, without really increasing the resolution. (which actually will be a boon for digital photography, since no one needs the current resolution anyway, because the optics doesn't keep up, but a megapixel race is on...)
But does anyone know why sensors use RGB and not CMY? a Cyan filter would let green and blue through, but keep red out, instead of blocking two parts of the visible spectrum for each pixel. This way, by simply switching color space, the camera becomes twice as sensitive to light. I.e. instead of use or something like that. One could even combine the two methods, and use white pixels, to gain a slight further increase in light sensitivity (from 8/12 to 10/12). Is there any reason that current cameras use RGB?
I'd Rather Have Less Noise, Wider dMax (Score:3, Interesting)
For me, though, the problem is not so much speed as it is noise and dynamic range. That's because a lot of the time I still do fine-art level landscape and studio glamour photography -- neither of which are speed starved, but even the finest digitals could still use even less noise and wider dynamic ranges.
While DSLRs have a huge advantage over handhelds in this regard, it would still be nice to see improvements in s/n such that the darker zones maintained their clarity and detail. Even the finest Canon cameras suffer to a degree in this regard, at least for people with very high standards. Some of us have those standards because that is what our clients demand - and in some cases we still must use film to meet their criteria.
It's a virtual law that to obtain the best noise performance you need to use the lowest ISO speed that the camera can attain. So instead of bottoming out at 100, like most DSLRs, I'd like to see 25. Or better, 12.
For more info, visit http://www.normankoren.com/digital_tonality.html [normankoren.com]
Where is the transparent pixel? (Score:4, Interesting)
One of the problems with DLP projection TVs with a "color wheel" was that since every color lets only 1/3 of the light through, the picture was dim. So they added a fourth element "clear" that lets out all the light to get every projected pixel a blast of light they need and the remaining portions of the color wheel adds only additional brightness for each color.
This technology seems to be kind of similar. The transparent sub pixel detects over all lumninosity and the remaining pixels "adjust" for color. Very close to what we have in our retina too. Almost all our cylindrical cells respond only to luminosity and the cones respond, to varying degrees, three colors. A poster was complaining about losing "color resolution". I think millions of years of evolution has shown us the balance. You need about 90% of the pixels responding to luminosity and just 10% to color. The same ratio in our retina.
Why not this pattern (Score:2, Interesting)
The patterns they suggested in the article were not as elegant as the Bayer filter (where each color formed an evenly spaced grid). They may be hiding the actual pattern for now or there may be some technical reason for those patterns that I don't understand, but I would suggest this pattern (C = Clear):
it keeps the same 4clear:2green:1red:1blue ratio but the different color pixels all form a regularly spaced grid.
Re:why are sensors in RGB instead of CMY? (Score:3, Interesting)
But I don't understand why you don't have less noise. The wikipedia article mentions higher dynamic range. Isn't it true that twice as much light falls on each sensor, so you gain a stop, and because of that have less noise (because you need the shutter open for only half the time)? Or is it somehow that when you get noise, it is in two channels, and thus you have the same amount of noise?
Re:CMOS version of Rods and cones (Score:4, Interesting)
The new Kodak filter pattern is still taking advantage of our better resolution for luminance, but is implementing it better by basing it on color filters (or the lack of them) that let more light through, thereby increasining signal-to-noise (especially needed in low-light conditions).
I'm not sure that this new filter pattern is optimal though. As another poster noted, R/G/B filters are too narrow and cut out a lot of light. You could still capture the color information with two broader filters more directly corresponding to the U & V of the YUV color space.
Other ideas for alternative color patterns (Score:5, Interesting)
1) Sony was building cameras for a while with four color channels. There was the normal green, but also a different green they called "emerald" for one of the four Bayer pattern locations. Unfortunately, this was a solution in search of a problem, it never really caught on because there just wasn't any perceived benefit.
2) I do visual effects for films. For the last 50 years or so, people have been using bluescreen and greenscreen effects. The idea is to put a constant color background, and process the image so that any pixels of that color become transparent. Over the years, more and more lipstick has been applied to this pig -- so that you can now often extract shadows that fall on the greenscreen, pull transparent smoke from the greenscreen plate -- these things have become even more possible through digital processing.
Still, it sucks. Greenscreen photography forces so many compromises that I often recommend shooting without it and laboriously hand-rotoscoping the shots.
But -- say you had a fourth color filter, with a very narrow spectral band. Perhaps the yellow sodium color -- commercial lights that put out very narrow-band yellow are sometimes used for street lighting. If you had a very narrow-band sodium filter over 1/4 of the pixels, you could pull perfect mattes without 99% of the artifacts of traditional greenscreen and bluescreen photography. Finally (and this is killer!) you could make glasses that the director of photography and other lighting crew could wear that block just that frequency, so they could see the set as it really is -- without the sodium light pollution.
Still, Kudos to Kodak for thinking outside the box.
Thad Beier
Re:why are sensors in RGB instead of CMY? (Score:3, Interesting)
Re:why are sensors in RGB instead of CMY? (Score:5, Interesting)
It is no coincidence (I suppose it's arguable if you call evolution a "theory" (with quotes)) that our eye is most sensitive to green light.
As a side note, the need for white balance on cameras is that spectral density for different light sources are not the same. Incandescents differ from fluorescents which differ from sunlight which is why incandescents have an orangeish tint and fluorescents have a blueish tint (that's where their frequencies have their peak power).
(The theory behind why chlorophyll is green (which means it reflects green and, thus, does not absorb the frequencies with the most power) are quiet interesting to boot.)
Re:Sacrifices color resolution: is it worth it? (Score:2, Interesting)
Re:why are sensors in RGB instead of CMY? (Score:2, Interesting)
How about using that new non-reflecting material? (Score:4, Interesting)