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Monochromatic sensor?

L

lambsporriegetta

New Member
Joined
Aug 14, 2007
Messages
25
is what ricoh should do....
use all the pixels for black and white raw images, quick to process and lots of quality.
that's my idea... mine! ,well probably not but i've never seen anyone suggest it before.
 
Nice idea and definitely yours! :D But I think the main problem is that no CCD/CMOS manufacturer actually making B&W sensors. And because Ricoh (as most digital camera manufacturers) obtains sensors from 3rd parties, it's unlikely to happen.

The truth is that all sensors are basically B&W. It's the RGB filters in Bayer pattern, which makes the sensors "color" sensitive. Remove them from sensor (along with antialiasing filter) and you have a pure B&W CCD/CMOS sensor. And most probably very good sensor with much sharper images! The Bayer pattern along with AA filter makes the images noticeably unsharp comparing them with output from pure B&W sensor. But I'm afraid, camera with such sensor would be really expensive..just because nobody makes such sensors. They would have to change their manufacturing process and do you think they would do this for let's say few thousands of CCD units? Of course, everything is just a matter of money. But definitely nice dream!
 
I don't think it is possible to make a bw sensor just by removing the bayer pattern. The bayer pattern is designed to have more green pixels than red and blue because our eye is more sensitive for green (if I'm right). By removing the bayer pattern, how does the software know it is dealing with green light or blue light?
The camera has to know which color to convert to which brightness.
I don't know if there is a solution to that.
 
I'm absolutely sure it's doable. But as you can see, this KODAK was probably the only commercial attempt of B&W camera. And its was higher about USD2000 than its color brother (at that time, when the price of this "color" Kodak was about USD 1000 higher than D1x).

I'm sure we will see some dedicated B&W cameras in a future. But I'm also pretty sure that it won't be anywhere near the current GRDII price and it won't be earlier than the appearance of "larger" sensor compacts. At the moment, we will have to stick with RAW, with which we can produce some incredible results ;)
 
Imar":2hekb0bc said:
I don't think it is possible to make a bw sensor just by removing the bayer pattern. The bayer pattern is designed to have more green pixels than red and blue because our eye is more sensitive for green (if I'm right). By removing the bayer pattern, how does the software know it is dealing with green light or blue light?
Click to expand...
CCDs are naturally panchromatic so there is no technical problem to using them to make B&W images. The real problem is making them sensitive to individual colours to make colour photography possible! The Bayer filter is simply a mosaic of red, blue, and green filters over the individual pixels which forces them to respond only to red, blue or green light. Half the filters are green, a quarter red and a quarter blue. It's a very simple kludge not unlike the way colour photographs were made in the early days of photography when three separate black & white exposures were made through red, green and blue filters.

If you were to remove the mosaic of RGB filters from a sensor, then the CCD would revert to being a simple b&w sensor, and as long as you worked with RAW files (ie. bypassed the camera's attempt to interpret the pixels as representing specific colours) there would be no problem. Unfortunately though the problem with the Bayer filter is that you can't simply take it off the front of the CCD when you want to make B&W photographs, as it is built into the chip during fabrication, because the tiny filters have to be precisely aligned over each pixel with sub-micron precision. Hence the need to set up a separate assembly line for B&W chips.
 
I don't understand it. If they put more green in the bayer filter to make it more realistic for our eyes, then in a bw version ccd they have to correct for the green as well, not? black and white is a translation of all colors into a gray scale. if that is done without a bayer filter, then green would appear much darker then the same amount of red or blue light...which is not representing how we see it.

What am I doing wrong?
 
There's two different issues there really. One is the spectral sensitivity of the eyes compared to that of the sensor, which gives rise to the problem you mention. This has always been an issue in photography, for instance normal B&W film is much more sensitive to blue than our eyes are, leading to the common suggestion to use a yellow filter to correct the tonal values. In the case of CCDs they are much more sensitive to red and infra red than our eyes. (The latter is dealt with by an filter in front of the sensor which blocks infra-red light.)

However the reason the bayer sensor has more green pixels is not really to correct this issue, which can be addressed simply with an overall correction filter or else by amplifying one colour signal more than another (which is in fact how white balance is achieved). Rather it is to reduce noise. Our eyes are sensitive to R/G/B in the proportions 30%/59%/11%, whilst the CCD is more like 50%/35%/15% so if they used an equal number of sensor pixels for each colour they would have to boost the green CCD signal by a factor of 3, which would boost the noise in precisely the part of the spectrum our eyes are most sensitive to. So instead they double the number of green pixels, which turns out to give a good compromise.

But if you were making a pure b&w sensor you'd have to go the correction filter approach the same as with film photography. Simply sticking a pale green filter over the sensor would do the trick I think.
 
Dragging up a zombie thread from before I joined, because it would be a great idea. Kodak made a monochromatic sensor way back in the early days of digital cameras. It was very technically successful and very commercially unsuccessful. I understand that there is a company out there that can do DSLR conversions, but bayer filter stripping is not as easy as ICF removal. I shoot Ricohs mostly for B/W so if they offered one with no filters at all and a screw on the front ICF for the regular price, I'd be a buyer.
 
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