Canon 3 Layer Sensor (Foveon Type?) Patent

[dr croubie]

Sigma sD1 has richer colors because of the independent layers.

maybe true, maybe not. unfortunately that's always going to be an apples vs bananas argument. lenses affect contrast, black/brass/silver aperture blades, coatings, even lens hoods do a bit too. so does the image processor it's attached to, and will most likely be tuned to whatever sensor type it's connected to.
try comparing 2 different car engines for performance, after they've been built in 2 different types of car with different chassis, wheels, suspension etc, and driving it around a track. you can infer which engine is better, but you'll never get an exact comparison. (sorry for the car analogy, top gear is on in the background).

One thing i've just noticed with the patent, compared to the X3 sensor (at least according to wikipedia): the canon patent specifically says that the blue is widest, then green, then red. the diagram of the X3 on wikipedia may be a simplification, but it looks like the colours are all the same width.


aside: a patent has to contain something new and/or innovative compared to another patent. maybe the width-difference is what canon is trying to set apart from the X3?

aside from the aside: these patents were (probably) written in Japanese, yes? can we get the original japanese patent and an electrical engineer who can read japnese from somewhere? anyone know anyone? these patents really are hard to decipher most of the time...

I wonder why they (Sigma) call it (SD1) 46Mp camera, because actually it produces 46/3~=15Mp pictures.

one word: marketing.

it *should* be called a 15mp picture, because that's how many dots you get at the end of the day. they've got 15m red, 15m blue, 15m green sensors, but on 15m unique spots.
but then a canon 15mp sensor has 5m blue, 5m green, 5m red sensors on 15m unique spots (with 15m lenses on top). one dot only takes one colour, and the processor guesses the values of other colours from the neighbour. so at the end of the day you get 15m dots. but the colour of those dots is only 1/3 definitely accurate, the other 2/3 are guess or interpolated.

(hmmm, by the same logic, my monitor is 1680*1050 pixels (1.7mp). but it actually has 1.7m red, 1.7m blue, 1.7m green on 5.3m unique sites. should i call my monitor 5040*1050?)

[Stuart]

I wonder why they (Sgima) call it (SD1) 46Mp camera, because actually it produces 46/3~=15Mp pictures. And "moderate" noise (mentioned in WiKi for Favion's new generation) + max ISO to 6400 mean that it's still significantly noiser Bayer's CMOS sensor (in 5dm2 ISO is up to 25600). So I still think it could be a patent for a medium-format product line

Does the 18MP canon have 18Million Red, and 18M Green and 18M Blue sensors on the sensor?

[kirillica]

I wonder why they (Sgima) call it (SD1) 46Mp camera, because actually it produces 46/3~=15Mp pictures. And "moderate" noise (mentioned in WiKi for Favion's new generation) + max ISO to 6400 mean that it's still significantly noiser Bayer's CMOS sensor (in 5dm2 ISO is up to 25600). So I still think it could be a patent for a medium-format product line

Does the 18MP canon have 18Million Red, and 18M Green and 18M Blue sensors on the sensor?

You still have separate channels and can handle them as separate pixel layers. And you still have 15Mp JPEG taken from SD1 and not 46Mp. So take it straight forward and not from marketing point of view

[FranciscoDurand]

I wonder why they (Sgima) call it (SD1) 46Mp camera, because actually it produces 46/3~=15Mp pictures. And "moderate" noise (mentioned in WiKi for Favion's new generation) + max ISO to 6400 mean that it's still significantly noiser Bayer's CMOS sensor (in 5dm2 ISO is up to 25600). So I still think it could be a patent for a medium-format product line

Does the 18MP canon have 18Million Red, and 18M Green and 18M Blue sensors on the sensor?

No, you silly its because its has 3 independent layers 15x3=45. And the 18mp bayer sensor has only 1.

[kirillica]

maybe true, maybe not. unfortunately that's always going to be an apples vs bananas argument. lenses affect contrast, black/brass/silver aperture blades, coatings, even lens hoods do a bit too. so does the image processor it's attached to, and will most likely be tuned to whatever sensor type it's connected to.

I was checking SD1 image gallery and should say: yes, colors are good, but detalization is average. You can boost your colors with editor, but what about details?

[polpaulin]

How long before someone posts they are not buying a new camera and waiting for one with the new Sensor?

me of course, I see no interest in upgrading  my 5D mark II
I shall upgrade only without AA filter or / and foveon-like sensor

[dougkerr]

I wonder why they (Sgima) call it (SD1) 46Mp camera

Because it is a larger number.

Best regards,

Doug

[kubelik]

I'd be great to see this done well: I don't think anybody would complain if a camera of the quality of the 5D Mark II were able to read RGB at each photosite.  I don't know that I'd settle for a 5D Mk III that only includes a Foveon-type sensor but doesn't improve other basic aspects of the camera like autofocus and continuous shooting rate.  high ISO on the SD 15 frankly looks terrible, based on the images from Photography Blog.  there's not any better noise handling than a regular APS-C cam, nor is there better color integrity.

I'm not so worried about the sharpness; the sample images for the SD15 are crisp enough and they're shot with Sigma lenses, which ... I have used for a long time but have to admit, don't compare to L glass.

the other question is price.  I'm not willing to pay 1Ds-series prices for a 5D-series camera just because it's got a Foveon-type sensor.  I don't know if the SD 15's ridiculous price was due to real production cost or a last gasp by Sigma's dslr division, but I simply won't pay that sort of a premium for a Foveon sensor.

[Osiris30]

Well, can someone translate into readable language what this patent is for and why it is (a way?) better than current stuff? 

Well the foveon sensor has 3 independent layers (blue, red, green) while the CMOS sensors has the bayer grid, the difference between those sensors is that the foveon captures all blue, all green, all red, images while the CMOS mix 'em all. You can read more in wikipedia sites  about this superb sensor and about the Sigma SD1.

And I think this sensor would be in the new Canon 5D Mark III? 

http://en.wikipedia.org/wiki/Foveon_X3_sensor

The Foveon actually *doesn't* have Red, Green or Blue layers.  I has layers that are sensitive to white, yellow and red in that order from top to bottom.  Blue and Green are determined based on math (white - yellow = blue), yellow-red = green.  Ofcourse it's not quite that simple because you ahve to do a lot of math as the light becomes less energetic as it reaches further down the sensel, so it ends up being horribly ugly math like G = Y-R*1.3243, and so on...

That's one reason you see weird colors sometimes in the Foveon output... depending on the energy of the light and the exact frequency it can screw up that math.

Foveon/Sigma's illustrations over simplify the imaging pipeline for the general public.  It's interesting that Canon refers specifically to RGB.. I would be very suprised if they could actual draw those colors out of a single sensel without reverting to Foveon like math.

[Osiris30]

The text is (as always) mostly unintelligible. and i wish the diagram was a bit larger.

ok, i've changed what i originally thought. It didn't look like a sensor on first inspection, but now i've convinced myself it is.

with the 'Set' FET off, nothing happens.
turn the Set FET on, and one of the TxR/G/B FETs on, and the voltage at the filled-in dot at the right will change proportionally to the voltage at the '101' layer.
Turn that FET off, turn on the next TxRGB FET, and read the voltage .

the line:
"Therefore, in reading the charge of B, it becomes difficult to receive light G, to prevent mixing"
mean that only one colour can be read at a time sequentially. Turning 2 or 3 FETs on at once, the voltage will be proportional to total charge on all 3 combined (added or averaged, not sure).
So you expose your sensor using the shutter, black it off, then read every pixel's colour sequentially before the charge dissipates (switching FETs on and off can be done in the order of nanoseconds).

turn the 'Res' FET on to reset the charges on everything.

Open all 3 FETs and you have a true monochromatic sensor!  I'll take 12

[Osiris30]

  high ISO on the SD 15 frankly looks terrible, based on the images from Photography Blog.  there's not any better noise handling than a regular APS-C cam, nor is there better color integrity.

You guys do realize the SD15 is nearly prehistoric as far as sensor age, and is a 1.7x crop (smaller than APS-C we're all used to in Canon land).  The new SD1 is a much better sensor (still not great), but lets compare apples to apples.

[smeggy]

http://en.wikipedia.org/wiki/Foveon_X3_sensor
The Foveon actually *doesn't* have Red, Green or Blue layers.  I has layers that are sensitive to white, yellow and red in that order from top to bottom.  Blue and Green are determined based on math (white - yellow = blue), yellow-red = green.  Ofcourse it's not quite that simple because you ahve to do a lot of math as the light becomes less energetic as it reaches further down the sensel, so it ends up being horribly ugly math like G = Y-R*1.3243, and so on...

This is wrong; do you have actual information that counters the link you quoted?
Case in point: white includes yellow, and blue, and red, and green. Take away the "white" and you're left with nothing for the other lower layers to detect!

I believe (and I could be wrong) that the Foveon X3's issues were a result of the variability of the thickness of the silicon layers. It is this depth that determines the wavelength cutoff.



This proposed Canon sensor will be inherently better because it won’t throw away 67% of the incoming light.
I’m sure folks would appreciate a much shorter exposure time by 1.5 stops, for free (all else equal).

This won’t be any better for video unless the data buses are clocked off faster to cater for the greater number of sub-pixels, or there is on-die pixel binning.

Anyway, all this is great news for photography. A microlensed, 10MP, true RGB per pixel, imager would suit me fine.

[kubelik]

  high ISO on the SD 15 frankly looks terrible, based on the images from Photography Blog.  there's not any better noise handling than a regular APS-C cam, nor is there better color integrity.

You guys do realize the SD15 is nearly prehistoric as far as sensor age, and is a 1.7x crop (smaller than APS-C we're all used to in Canon land).  The new SD1 is a much better sensor (still not great), but lets compare apples to apples.

well, I was comparing it to Canon APS-C sensors, not FF if you read my post.  also, I dare say even an XSi's sensor doesn't look a whole lot worse at ISO 1600 if you really want to compare old apples to old apples.

Canon's definitely got a much better chance than Sigma at pulling off this sort of new technology.  I agree that it's hard to tell how much of this is limitations in the technology itself and how much of it is limitations in Sigma's budget.

[Osiris30]

http://en.wikipedia.org/wiki/Foveon_X3_sensor
The Foveon actually *doesn't* have Red, Green or Blue layers.  I has layers that are sensitive to white, yellow and red in that order from top to bottom.  Blue and Green are determined based on math (white - yellow = blue), yellow-red = green.  Ofcourse it's not quite that simple because you ahve to do a lot of math as the light becomes less energetic as it reaches further down the sensel, so it ends up being horribly ugly math like G = Y-R*1.3243, and so on...

This is wrong; do you have actual information that counters the link you quoted?
Case in point: white includes yellow, and blue, and red, and green. Take away the "white" and you're left with nothing for the other lower layers to detect!

I believe (and I could be wrong) that the Foveon X3's issues were a result of the variability of the thickness of the silicon layers. It is this depth that determines the wavelength cutoff.



This proposed Canon sensor will be inherently better because it won’t throw away 67% of the incoming light.
I’m sure folks would appreciate a much shorter exposure time by 1.5 stops, for free (all else equal).

This won’t be any better for video unless the data buses are clocked off faster to cater for the greater number of sub-pixels, or there is on-die pixel binning.

Anyway, all this is great news for photography. A microlensed, 10MP, true RGB per pixel, imager would suit me fine.

Here you go, one pretty picture to show what actually happens:

http://en.wikipedia.org/wiki/File:Foveon_rgb.png

If you go *read* the Foveon white papers (especially the pre-sigma ones, when they were shopping the tech), you'll see that the sensors don't output RGB at all.  RGB is mathed out of the Foveon sensel output.

(edit) oh and re your response to someone else's 67% comment.  There won't be any change in exposure times, it will just be a change in gain applied to the chip if you gather more light.  In theory you could net more DR.

[Osiris30]

  high ISO on the SD 15 frankly looks terrible, based on the images from Photography Blog.  there's not any better noise handling than a regular APS-C cam, nor is there better color integrity.

You guys do realize the SD15 is nearly prehistoric as far as sensor age, and is a 1.7x crop (smaller than APS-C we're all used to in Canon land).  The new SD1 is a much better sensor (still not great), but lets compare apples to apples.

well, I was comparing it to Canon APS-C sensors, not FF if you read my post.  also, I dare say even an XSi's sensor doesn't look a whole lot worse at ISO 1600 if you really want to compare old apples to old apples.

Canon's definitely got a much better chance than Sigma at pulling off this sort of new technology.  I agree that it's hard to tell how much of this is limitations in the technology itself and how much of it is limitations in Sigma's budget.

Sorry I picked your post to reply to, but I could have picked a myriad of others.  It wasn't directed at you specifically, but the discussion as whole where people are comparing and contrasting output.  'Only goes to ISO 6400, my 5DMK II does 25,600'.  Comments like that abound on this thread.

I'm not saying I support the Foveon concept, or that it doesn't have flaws, but maybe a new take at it (like Canon's) might prove interesting.