Eric Fossum

Eric Fossum

Lives in United States Hanover, NH, United States
Works as a Imaging Technology
Has a website at http://ericfossum.com
Joined on Jan 6, 2006
About me:

Primary inventor of modern CMOS image sensor technology.
See my website for more biographical information.

Professor, Thayer School of Engineering at Dartmouth

Comments

Total: 48, showing: 1 – 20
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In reply to:

Eric Fossum: I should mention here that I have been working with Rambus for a few years and they fund our Quanta Image Sensor R&D at Dartmouth, along with other projects elsewhere. I believe their strategy is to invest in R&D that yields fundamental IP in advanced areas. It is an interesting business model and one that actually supports innovation and technology development even if they are ultimately a non-practicing entity.

With all due respect Wilmark, I don't think you really understand what a patent troll is. And even the most evil patent trolls out there are perfectly legal in what they do. Suggesting otherwise is just silly. Anyway, a patent troll does not spend money to develop new technology and teach it to others. Of course they want people to adopt the technology so they can generate licensing revenue, but it is an eyes-wide-open scenario. Just like Nikon wants you to buy their technology so they generate revenue. No trickery or underhanded activity going on there. And yes, I am aware of Rambus' infamous and unflattering past. I wouldn't work with Rambus of old.

Direct link | Posted on Feb 28, 2013 at 19:32 UTC
In reply to:

Nikonb: look at this
http://www.design-reuse.com/articles/7411/variable-integration-time-image-sensor-for-wide-dynamic-range.html

check the last reference on that paper.
There are many ways to do HDR. Using multiple exposure times is an old idea and we did one of the first sensors using this method nearly 20 years ago. The Rambus binary pixel approach goes well beyond this.

Direct link | Posted on Feb 28, 2013 at 14:54 UTC
In reply to:

Eric Fossum: I should mention here that I have been working with Rambus for a few years and they fund our Quanta Image Sensor R&D at Dartmouth, along with other projects elsewhere. I believe their strategy is to invest in R&D that yields fundamental IP in advanced areas. It is an interesting business model and one that actually supports innovation and technology development even if they are ultimately a non-practicing entity.

@Timmbits. Thanks for looking out for me. Fortunately I am fairly experienced in these matters.

Direct link | Posted on Feb 28, 2013 at 02:59 UTC
In reply to:

Eric Fossum: I should mention here that I have been working with Rambus for a few years and they fund our Quanta Image Sensor R&D at Dartmouth, along with other projects elsewhere. I believe their strategy is to invest in R&D that yields fundamental IP in advanced areas. It is an interesting business model and one that actually supports innovation and technology development even if they are ultimately a non-practicing entity.

There is only one Rambus. I think they have had a strategic change in the way they do business since their initial infamous foray. I like the new business model and support it. On the other hand, patent trolls (non inventive NPEs) are truly a parasite on our economy.

Direct link | Posted on Feb 28, 2013 at 00:16 UTC
In reply to:

Roland Karlsson: I see no technical explanation on how it works. Any one knows? Or have a pointer?

Vogelsang, T.; Stork, D.G.; , "High-dynamic-range binary pixel processing using non-destructive reads and variable oversampling and thresholds," Sensors, 2012 IEEE , vol., no., pp.1-4, 28-31 Oct. 2012
which builds on work by Vetterli et al at EPFL (gigavision camera), and which, to some degree, is related to my work.

Direct link | Posted on Feb 27, 2013 at 21:46 UTC
In reply to:

forpetessake: Going to the logical end, a single pixel can work in a binary mode (detecting light or darkness) similar to dithered images of printers. When they create pixels with 50nm pitch then it can be possible to have image quality close to today's sensors.

But pretty soon, they will hit the law of diminishing returns, the quantum noise is determined by the total light collected by the surface of the sensor. For example, even ideal (noiseless) micro 4/3 sensor will not be able to achieve the performance of today's (not ideal) FF sensor.

why 50 nm? What are your assumptions?
You are also forgetting about improvements in QE.

Direct link | Posted on Feb 27, 2013 at 20:09 UTC
In reply to:

Nigel_L: Reminds me somewhat of a forum post I made a few years ago...

See http://forums.dpreview.com/forums/post/18895569

Regards, Nigel

indeed Nigel. Ahead of your time, but I was ahead of you by "a bit" as were a few others.

Direct link | Posted on Feb 27, 2013 at 19:19 UTC

I should mention here that I have been working with Rambus for a few years and they fund our Quanta Image Sensor R&D at Dartmouth, along with other projects elsewhere. I believe their strategy is to invest in R&D that yields fundamental IP in advanced areas. It is an interesting business model and one that actually supports innovation and technology development even if they are ultimately a non-practicing entity.

Direct link | Posted on Feb 27, 2013 at 19:16 UTC as 39th comment | 10 replies

I made some comments on this in the news forum yesterday including a reference to technical work they published. Bottom line, I am a big fan of binary pixels and oversampling (spatially and temporally) and believe this is where things are headed even for large sensor cameras.

I see there is some wrong information being circulated in this comments section so readers, beware!

Direct link | Posted on Feb 27, 2013 at 19:10 UTC as 41st comment
On Just Posted: Lytro Light Field Camera review and video article (309 comments in total)

Fad or no fad it is improved job security for image sensor technologists!
Kind review article DPR. I hope Ren Ng's dream comes true.

Direct link | Posted on Mar 1, 2012 at 17:38 UTC as 29th comment
On Fujifilm patents hybrid organic/CMOS sensor article (82 comments in total)
In reply to:

ziggy53: If I understand this new technology, a lens array is not required and the color filter array positioning may be somewhat non-critical making possible the deferring of photosite color sensitivity until after a "calibration" step?

What this might mean, for example, is replaceable color filters, over the imager, with patterns ranging from a tradition R-G-B-G pattern to other distributions more suited for scientific or specific applications; perhaps a "stochastic" color filter array to alleviate color aliasing effects (when photographing subjects with regular color patterns) and to provide a better color film simulation.

While the technology is apparently intended for small sensors, imagine a super-dense large-ish (APS-C sized) sensor. It would not need an AA filter (because of the high photosite density) and intrinsically the sensor doesn't need a lens array. Make the color filter array interchangeable, or even optional, and all sorts of things become possible.

Sorry Ziggy but you are kind of tripping here. Among many problems with your suggestion, what happens if a small particle of dust gets onto the sensor surface between the hypothetical removable CFA layer and the sensor? What if the CFA RGB is misaligned by half a pixel? What about rotation alignment? I could go on with other problems but someone will accuse me again of being related to Debbie Downer again.

Why don't you suggest a camera with removable sensors, each with a different CFA pattern (or none)? Removable sensors have enough problems to keep you busy for a long while.

Direct link | Posted on Dec 23, 2011 at 02:46 UTC
On Fujifilm patents hybrid organic/CMOS sensor article (82 comments in total)
In reply to:

random78: Based on the quote from Fuji authors it seems that the major gain is increased light-capturing efficiency specially at smaller pixel sizes. Unfortunately fossum did not really address this properly. Of course he could be right and this technology might not be "disruptive". But overall his comments are very general and from his comments it does not seem that he has a detailed idea about the extent of gains possible through this technology. These are like the comments from an industry analyst rather than from an engineer intimately familiar with the technology in question.

Actually, I pointed out the distinct advantage of the higher absorption coefficient for the Fujifilm organic material. Sorry you missed that. But, without noise reduction such an advantage is moot. Also, Fujifilm has not demonstrated this material in a competitive (e.g. 1.4 um) pixel size yet.

Direct link | Posted on Dec 23, 2011 at 00:56 UTC
On Fujifilm patents hybrid organic/CMOS sensor article (82 comments in total)
In reply to:

Eric Fossum: I'd like to think I am still on the innovator side of the curve and most of my technical friends know I am somewhat bored with the CMOS image sensor technology. I am actively on the look out for the "next thing". Still, just because something is new and interesting does not mean it does not deserve a critical eye. I tried to point out what may be shortcomings of the technology relative to the 2009 Fujifilm paper, which is all I know about the specific Fujifilm device. I will check in later to see if someone has something technical to offer besides just general pot shots. I did find the Debbie Downer comment funny. She is just a distant relative, I believe.

I think the random read noise number comment was very specific. You probably would not want to buy a digital camera today with such high read noise. The pixel size is also non-competitive with state of the art "small pixel" sensors. Other figures of merit that were given in the Fujifilm paper were fine (e.g. dynamic range) but not outstanding so I did not comment on them. Butler just asked for some comments from me on a paper he sent me. Let's not make this out to be some sort of detailed analysis position paper.

Direct link | Posted on Dec 23, 2011 at 00:51 UTC
On Fujifilm patents hybrid organic/CMOS sensor article (82 comments in total)
In reply to:

KitHB: This does raise another interesting possibility. There's lots of work happening now on flexible materials for electronic components.

What if the CMOS substrate in the picture above happens to be a flexible film?
Doing away with the microlenses means you don't absolutely need it stuck to a rigid base.

Which optical corrections become possible by curving the sensor plane or even distorting parts of the sensor in response to the lens settings? Make tilt-shift lenses obsolete and have front to back sharpness every time? correct curvature in mega-zooms? embed cameras into wearable surfaces?
.mil would love those capabilities.

It is not likely the single crystal silicon substrate will be a flexible film. It is possible the Fujifilm approach makes such implementation easier but first Fujifilm has to make the basic structure work well before moving on to flexible substrates.

Direct link | Posted on Dec 23, 2011 at 00:45 UTC
On Fujifilm patents hybrid organic/CMOS sensor article (82 comments in total)
In reply to:

ziggy53: If I understand this new technology, a lens array is not required and the color filter array positioning may be somewhat non-critical making possible the deferring of photosite color sensitivity until after a "calibration" step?

What this might mean, for example, is replaceable color filters, over the imager, with patterns ranging from a tradition R-G-B-G pattern to other distributions more suited for scientific or specific applications; perhaps a "stochastic" color filter array to alleviate color aliasing effects (when photographing subjects with regular color patterns) and to provide a better color film simulation.

While the technology is apparently intended for small sensors, imagine a super-dense large-ish (APS-C sized) sensor. It would not need an AA filter (because of the high photosite density) and intrinsically the sensor doesn't need a lens array. Make the color filter array interchangeable, or even optional, and all sorts of things become possible.

There is nothing in the Fujifilm paper I read to suggest that replaceable color filters are enabled by their technology.

Direct link | Posted on Dec 23, 2011 at 00:39 UTC
On Fujifilm patents hybrid organic/CMOS sensor article (82 comments in total)
In reply to:

TOF guy: I'll ask Dr. Fossum since he is the in-house expert Is the idea really new? A similar scheme is found in some detectors for scientific applications (example, X-ray detectors http://www.dectris.com/sites/technology.html). Where Fuji inovates is that they discovered a material converting photons to charges which is sensitive to much lower energy photons than X-ray. If correct the key difference (not explained by dpreview above) is that there is no well in these sensors. The photons are counted as they come. What limits DR is how fast the charges are counted. Useless to say DR can be way above well-based (CCD/CMOS) sensors. There is no blooming either. For X-ray, noise and sensitivity exceeds back-illuminated CCD in spite of (currently) somewhat poor surface coverage. Also it should be easy to design the sensor to provide true syncing with a flash at least to 1/500 sec (the flash becomes the limiting factor!).

I am not an in-house guy. I am just a visitor like you. The paper that Butler sent to me (not the patent) did not mention photon counting so I am not sure where you see the similarity. Fujifilm and NHK have both been pursuing organic films for photodetection. (Together, for a while). I don't recall seeing them (or anyone else) combining CFAs and a panchromatic-response thin film. So, seems relatively new to me.
Photon counting is a whole different concept, not conceptually new, and not really related to this news story either as far as I know.

Direct link | Posted on Dec 22, 2011 at 07:45 UTC
On Fujifilm patents hybrid organic/CMOS sensor article (82 comments in total)

I'd like to think I am still on the innovator side of the curve and most of my technical friends know I am somewhat bored with the CMOS image sensor technology. I am actively on the look out for the "next thing". Still, just because something is new and interesting does not mean it does not deserve a critical eye. I tried to point out what may be shortcomings of the technology relative to the 2009 Fujifilm paper, which is all I know about the specific Fujifilm device. I will check in later to see if someone has something technical to offer besides just general pot shots. I did find the Debbie Downer comment funny. She is just a distant relative, I believe.

Direct link | Posted on Dec 22, 2011 at 02:49 UTC as 11th comment | 2 replies
In reply to:

forpetessake: Can somebody knowledgeable explain, why do we still have an ISO setting in cameras with CMOS sensors? As far as I understand from this presentation, CMOS sensors have separate amplifiers for each pixel. That means that the gain of every amplifier can be set for optimal signal/noise ratio for the amount of light the pixel received. In other words we won't have an ISO setting for a sensor, rather a camera can set an optimal ISO (gain) for each pixel. So we can get rid of ISO setting on one hand and get the best possible dynamic range from the sensor under each given light condition on the other. So why don't we see this implemented in modern CMOS sensors, or is it?

So in this scheme I think you need two exposures. One to figure the right gain settings, and one to take the larger dynamic range image, and hope nothing bright or dark moves in between the two shots.
If you are going to take two exposures there are many ways to achieve high dynamic range - like one short and one long exposure fused together.

Direct link | Posted on Nov 6, 2011 at 17:10 UTC

Thanks all for your comments. I may not return to this discussion now for some time so please don't look for a response from me.

Direct link | Posted on Nov 5, 2011 at 10:57 UTC as 1st comment
In reply to:

Neoasphalt: Mr. Fossum,
I would like to get answer from expert as you on the following question - if the given size sensor pixel density would be reduced, lets say four times, from common 16 to 4 MP (enough for people who don't print their images) and made with the same latest CMOS technology, will this result to significantly:
1. Lower noise
2. Higher dynamic range
3. Better tonal range
4. Higher color depth
5. Cheaper production costs
6. Or other possible improvements?

Thank You

Actually the smaller pixels will give better slightly better results if the image quality is read noise limited, since the noise will grow 2x if you add together 4 pixels. Also the color resolution will be better. Due to color processing, having at least a full Bayer kernel with in the Airy disk is better than each kernel element being roughly the size of the Airy disk since color processing reduces resolution anyway.

Direct link | Posted on Nov 5, 2011 at 10:54 UTC
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