Final output of the Foveon X3 ?

[Ron Parr]

There is NO "overlap" with the Foveon X3 approach - as long as you
are relating it to 3.54mps. With Bayer/interpolation ... there is
overlap as soon as you go above 1.5mps.

I think didn't quite get the kind of overlap we're talking about.

There is plenty of overlap in the absorption curves for each
photosite. I suggest you read the patent and look at Figure 8.

But we do not know yet how much that may affect image quality.
They may have it "figured out".

Sure. I'm not saying that it's a dealbreaker. I was just noting that it's a possible issue.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

 

[David Barkin]

Hi Ger

Thanks for the post. The first succesful post to ecplain this to a lay person. No kidding.

Dave

It's my understanding that in fact it takes twice as many sensors
to make one image pixel then with the Foveon. On a D100 for
example, you are in effect having a 3MP camera. It then
interpolates up to get the 6MP.

Try this - each pixel records a value of 1/3 as one needs three
pixel readings to make a guess at the colour to be assigned to any
group of pixels. The actual shade of each pixel is known, as this
is the actual reading from the vibrations from each pixel that is
assigned to picture capture.

Thus your resolution is not effected and one will still get 6MP
from a 6MP chip (loosely) but one carries only 1/3rd (or ) of the
total colour information – that’s actual information read from as
many as nine pixels just to assign the central pixel with a
guesstimated colour – it only reads actual vibrations and they are
measured on a maximum of 256 individual shades – it knows the
actual colour over every pixel and that never changes. The shade in
each of the individual Red, Green & Blue filters can run from pure
white to pure black and at least three readings are needed to offer
any individual pixel its colour.

Thus one can say that one has 6MPs resolution (sharpness) but only
2MPMs of colour data collected and included within the final output
(and if you like redistributed over the palette). Thus our CCDs can
often give “flat” results but with adequate sharpness.

The Foveon depends on the actual radiation signature penetration
depth and vibration to determine its colour on each and every pixel
assigned to picture capture. It can do this very accurately so it
can use its colours to define borders. The 3X can actually detects
both the shade and actual colour for every pixel (the CCD can
detect only the shade) so every tiny nuance can be recorded. This
afford the image a sharpness derived from its accurate colour
definitions – over any given surface distance the 3X will detect a
colour change for every pixel whereas the CCD will assign colours
based on thee pixels and will thus record shading less accurately
and have a “soft” look to them.

For colour printing the effect is like needing 1 pint to fill a
square.

From the CCD one is only given 1/3rd of a pint but one has to fill
the square anyway.
From the 3x one is given most of the pint to fill the square.

Given that we are actually “happy” with the results from using
1/3rd of a pint to fill our squares from our CCD, if we then spread
the 3X’s pint around more we get a result very similar to that of
the CCD but because the colour also defines the image we also loose
less sharpness – the CCD needs resolution to define sharpness.
Think of that one like drawing our square and then washing our
colour around INSIDE it – think of the 3x like painting the square
with the same brush as we fill with.

 

[G. Lentz]

I was wrr... wrro... my information was deficient ;-)

I took another look at the Fuji Super-CCD and it is indeed a grid rotated 45°.

OK then, so how about a fully interleaved HEXogonal grid??

I also noticed somthing on one of the SD-9 sample photos... the one with the cars. It feels, to me anyway, that this image is remarkebly flat... like the foreground leaves appear to lie in the same plane as the yellow car. It looks as if the leaf borders are so sharp as to have negated the visual cues for depth. It almost gives the impression that the photo has been matted.

Unpleasant to me, in any sense.

", this
concern appears justified. A pixel array similar to the Super-CCD
(which, I believe, consists of interleaved octoganol pixels, not
just a rotated grid) may help to at least disquise this effect.

This discussion indeed deals with resolution. Perhaps we should be
discussing final sharpness instead? After all, an image that is
twice as sharp from the go, independent of DSP, could always be
upsampled to a larger size, and as a result of the dithering
involved may possibly even be more aesthetically pleasing in its
more natural smoothness.

I'm not saying that the Foveon is twice as sharp as a Bayer, but
there is a certain 'sharpness' already inherent in the design, by
virtue of the fact that you don't have to perform extensive matrix
computations to recover (read 'guesstimate') the original value of
a given photopoint.

-gl

After all, any CCD array can become a super CCD by simply rotating
its grid orientation by 45 degrees in the image plane. What does
that really buy? Not a whole lot, IMO, since it takes the same
number of measurements in the same area as the non-super-CCD of the
same number of effectiove pixels.

MarvinK

Just thought I'd follow up on my follow-up:

A few things came to mind after I wrote this.
...
...
4. I wonder what advantages there would be, if any, to Foveon
adopting a
pixel layout like the one on the Super-CCD??

Of course, it's all guessing until we start seeing reviews from
production cameras, yeah?

-gl

 

[JoePhoto]

At the moment we can only
discuss "theoritical" possibilities. And again ... we are
SPECIFICALLY discussing the "resolution" possibilities of the X3
technology - and comparing it to Bayer/Mosiac technology.

The only problem is, that like I said, theoretical cameras can only
take theoretical pictures.

Therefore .... it remains to be seen if it is true .. but the
POTENTIAL is there for the X3 to be DOUBLE the resolution of
existing 6mps. (And without color morie/artifacting).

The main problem with your theory is that mosiac sensors appear to
produce better resolution in the real world than you give them
credit for. There is a lot of room for tweaking in demosiacing
algorithms (which bring me back to why you have to compare
implementations and not theories.)

The main objection I had in this thread was the description of the
X3 output as "true color" as if it were capable of measuring the
precise amount of red, green, blue light falling on it. It just
ain't so.

I assume you are talking about cross-polination where some parts of each color will also affect the other colors to some degree. But that is also true of FILM that we loved for so many years. It actually worked somewhat like the X3 technology.

Since our Holy-Grail here is "comparing" digital to film; I suggest that maybe it won't be any worse problem than it was.

At any rate ... I disagree with your suggestion that current produce better photos than I give them credit for. I will not accept any "morie" or color-artifacting IF there is the slightest possibility of eliminating it. The X3 offers that "promise" ... I HOPE THEY SUCCEED.

Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

 

[JoePhoto]

There is NO "overlap" with the Foveon X3 approach - as long as you
are relating it to 3.54mps. With Bayer/interpolation ... there is
overlap as soon as you go above 1.5mps.

I think didn't quite get the kind of overlap we're talking about.

There is plenty of overlap in the absorption curves for each
photosite. I suggest you read the patent and look at Figure 8.

I agree ... but there also is with FILM. Since "matching/equaling" film is the first goal; maybe that is not an unsurmountable problem.

http://l2.espacenet.com/dips/bnsviewer?CY=ep&LG=en&DB=EPD&PN=US5965875&ID=US+++5965875A1+I+

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

 

[JoePhoto]

No.

The advantages are in better reproduced colour and lack of moiré
patterns in certain situations.

There is no real gain in sharpness or picture resolution.

YES ... there is the potential of DOUBLE the resolution AND SHARPNESS of current 6mps senors.

Up to this point in this age of digital technology I found that all
things being equal go with more pixels if you want to print your
pictures larger. That is the reason I have a 6mp DSLR. So my 6mp
file is 3024x2016 if I want to print a 18x12in. (Epson 1280) my
printing resolution is 168 pixel/inch.... barely acceptable. So
here is the question, the Sigma Foveon is 2268x1512 so if I want to
print 18x12in. will be at 125pixels/inch. Will the Foveon X3 CMOS
produce a much better 18X12in. print compared to the present 6mp
DSLR?

Your "file" may be 3024x2016 ... but that is INTERPOLATED, (guessed), data. You actual resolution/sharpness is only 1.5mps ... anything above that is a GUESS. (albeit an "educated" guess ... but still a guess)

If you interpolate the X3 file to 6mps ... it will also be a guess ... but TWICE AS ACCURATE since it had more than double the original data to begin with.

Boris

--
Derek

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

 

[JoePhoto]

Hi Ron

You are resonding to technical posts with technical posts. Fine.
This post is not meant as a critique of that.

But what I'd like to know is if we're comparing apples and oranges
or apples and apples.

Is there a realistic comparison possible? Is the Foveon chip equal
to a bayer chip twice it's size, 50 percent?

Is the fact that there are different implementations of the bayer
chip a problem and to what degree?

If you can make such a comparison let it be on the basis of the
best existing bayer pattern.

I don't mean to put you on the spot. Exisiting terminology and the
lay understanding of this is that when a camera is rated at 6MP
it's going to be twice as powerful as a 3MP. Along comes Foveon and
the exisiting ratings don't seem to mean much.

So my question really boils down to assigning ratings to chips that
will make some sense to the person going out to buy a camera.

Dave

Foveon (X3) faced a decision. They could very easily have simpy called their chip a 10.62 mps and we would not be "arguing" about it.

(They could even have gone a step further and say it "equals" a Bayer 14.16mps chip since they have R-G-B-B)

But instead they made a tactical decison to help illustrate their "different" technology by adopting an entirely new rating system that is indeed MORE ACCURATE and HONEST.

To illustrate my point ... imagine for a minute a white wall with RED DOTS. Not imagine the density of those dots exactely equals 3.54mps.

If you photographic that wall with a 6mps sensor ... there are TWO VERY DIFFERENT POSSIBILITIES ... one is that the red "dots" exactely align with the RED-SENSORS ....

another possibility is that they do not align with any of the red sensors.

However ... EVEN IF they DO "align" perfectly ... you will NOT GET A PERFECT "RED" DOT .. because the "interpolation" will mix in the "white" from the adjoining sensors and reduce its brilliance to a lighter shade of "pink".

The second possibility, (and 3X as likely since there is only 1/4 "red" sensors); of NONE of the red dots aliging with the red sensors produces an almost HORRIFYING RESULT. I could not even attempt to tell you what would happen.

HOWEVER ... that same scenario on a X3 sensor would produce a PERFECT IMAGE of "RED" dots.

No.

The advantages are in better reproduced colour and lack of moiré
patterns in certain situations.

There is no real gain in sharpness or picture resolution.

The goal is to have improved sharpness and picture resolution.
Moire is a symptom of the undelrying problem Foveon is trying to
fix. It's not the problem.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

 

[S Clark]

What you need to do is resample both cameras photos up to 18x12 at 300ppi and then print them.
--
http://www.pbase.com/galleries/sasc

 

[JoePhoto]

So my question really boils down to assigning ratings to chips that
will make some sense to the person going out to buy a camera.

I'm afraid that there's no magic formula. It's like trying to
compare stereo equipment by using the specifcations. The
specifications give you some rough guidelines, but in the end there
are many factors that can't be captured by a few numbers. You need
to use your ears and go with the one that sounds best.

For the Foveon vs. Bayer thing. I'm not interested in trying to
predict some magic multiplier that will convert from one to the
other. In most of my posts, I'm just trying to address some
misunderstandings about what the technology does and what the
motivations behind it are.

I do NOT agree ... it is VERY EASY to make a "comparason" ... you simply have to know if it is a R-G-B or R-G-B-B arrangement.

In the first case ... simply divide the mps rating by 3 ... and 4 if a RGBB.

Does that tell you the ultimate quality of the camera ?

Of course absolutely NOT ... just as all cameras vary in image quality.

BUT you "question" was how to compare X3 technology to all previous cameras. We simply have to realize that we were essentially LIED to in the past ... and Foveon is being HONEST in their rating.

In the end, you should read reviews from people you trust, like
Phil, and use your eyes to decide which produces the best images.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

 

[Mike Fried]

Seems to me that the way to get some insight into this is to do
your own
comparisons of your images from a Bayer CFA camera with images
in which you make nearly ideally "real pixels" by downsizing a very
high-res capture of a scene. It shouldn't be hard to simulate a small
X3 sensor, say 1 MP, by downsizing a 6 MP image, and then reframe
and see how many of your pixels you need to use to match the
sharpness and quality, say on 5x7 or 8x10 prints.

Has anyone tried that?

I did something very similar to that a while ago. I took my cameras images, resampled them down by 2 in vertical and 2 in horizontal, and tried my hand at using Bayer-like techniques to get the lost information back. It's a good experiment. Bilious is on the money here. This leads to a lot of insight into how "Bayer resolution" works.

Here's my take at an answer to the original poster's question regarding 3.5 X3 MP and 6MP bayer resolution. I also raised this same question around the time of the first X3 announcement/initial speculation. You might find that thread a good read as well: http://www.dpreview.com/forums/read.asp?forum=1014&message=2189235

Remember that resolution in terms of Pixel Count is misleading because you have 2 dimensions. And 3 or 4 colors. Imagine now that we take resolution in the way that Foveon treats it scientifically. Say you have a 6MP Bayer CFA sensor (RGGB). You have 3MP of Green, 1.5MP of Red, and 1.5MP of Blue. I will make the argument that you have 3MP of resolution simply because you are significantly more sensitive to luminance (as in overall brightness, and green is the most bright). Now, the fact that the sensors are not overlapping is dealt with to some extent by fancy algorithms and by microlenses.

Now look at the foveon sensor. For each pixel location, there are 3 sensors. The resolution is absolutely 3.5MP. There are 10.5 Million sensors. Also, noise should be better with the Foveon. With a Bayer pattern sensor, every amount of noise that is in the system effects all pixels related to that sensor. For a specific sensor, that means it's four to nine pixel neighborhood will be off by some amount. With the foveon sensor, each bit of noise will only affect one pixel. The grainyness of the noise will be within one color channel of one pixel.

So in a nutshell, 3.5 X3 (10.5M Sensors)= 3.5MP of useable Color Resolution, 6MP Bayer (6M Sensors) = 3MP of Resolution, 1.5MP of Color resolution. That's how I look at it now.
-Mike
--

A camera is a camera. You don't need a better one to take better pictures, you just need to take better pictures.

 

[Ron Parr]

I do NOT agree ... it is VERY EASY to make a "comparason" ... you
simply have to know if it is a R-G-B or R-G-B-B arrangement.

In the first case ... simply divide the mps rating by 3 ... and 4
if a RGBB.

It's really not that simple. You primarily notice detail in the green channel and you're unlikely to notice any cheating in the blue or red channel. This is why they use R-G-B-G pattern. Such a pattern will look better to your eye than a simple R-G-B. That's why they do it. These guys who make cameras aren't stupid, but your reasoning above actually suggests that the mostly widely used Bayer pattern will have lower apparent resolution than the simple one.

In reality most of our perception of detail does come from the green channel, so for most images the fact that half the pixels are green will be sufficient to give the perception of around half the stated resolution.

Now you have the problem of interpolation. Yes, interpolation is guessing information and it's impossible to be right all of the time. However, it's also impossible to be wrong all of the time. The actual performance is somewhere in the middle.

Finally, there are other issues like noise, etc. If there are other sacrifices made to achieve an X3 solution, then some things like noise could degrade the image and reduce any theoretical benefit you might have hoped to achieve.

I'm not saying any of this discourage you on the X3 sensor. I'm very excited about it and I'm mostly on the other side of these arguments, trying to defend it against people who want to shoot it down. In this particular case, however, I think you need to be more realistic. It's a complicated system and there are many factors.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

 

[David Barkin]

Hi Joe

Ok, I'm going to try your experiment, not having a large white wall, I'm going to try painting my pure white 110 lb dog with red dots. Now how large should I make these dots and how far away should I stand. Also, if the dog objects what do I do? What kind of paint should I use or should I just shave the dog after the experiment?



Thanks for the post...

Dave

Hi Ron

You are resonding to technical posts with technical posts. Fine.
This post is not meant as a critique of that.

But what I'd like to know is if we're comparing apples and oranges
or apples and apples.

Is there a realistic comparison possible? Is the Foveon chip equal
to a bayer chip twice it's size, 50 percent?

Is the fact that there are different implementations of the bayer
chip a problem and to what degree?

If you can make such a comparison let it be on the basis of the
best existing bayer pattern.

I don't mean to put you on the spot. Exisiting terminology and the
lay understanding of this is that when a camera is rated at 6MP
it's going to be twice as powerful as a 3MP. Along comes Foveon and
the exisiting ratings don't seem to mean much.

So my question really boils down to assigning ratings to chips that
will make some sense to the person going out to buy a camera.

Dave

Foveon (X3) faced a decision. They could very easily have simpy
called their chip a 10.62 mps and we would not be "arguing" about
it.

(They could even have gone a step further and say it "equals" a
Bayer 14.16mps chip since they have R-G-B-B)

But instead they made a tactical decison to help illustrate their
"different" technology by adopting an entirely new rating system
that is indeed MORE ACCURATE and HONEST.

To illustrate my point ... imagine for a minute a white wall with
RED DOTS. Not imagine the density of those dots exactely equals
3.54mps.

If you photographic that wall with a 6mps sensor ... there are TWO
VERY DIFFERENT POSSIBILITIES ... one is that the red "dots"
exactely align with the RED-SENSORS ....

another possibility is that they do not align with any of the red
sensors.

However ... EVEN IF they DO "align" perfectly ... you will NOT GET
A PERFECT "RED" DOT .. because the "interpolation" will mix in the
"white" from the adjoining sensors and reduce its brilliance to a
lighter shade of "pink".

The second possibility, (and 3X as likely since there is only 1/4
"red" sensors); of NONE of the red dots aliging with the red
sensors produces an almost HORRIFYING RESULT. I could not even
attempt to tell you what would happen.

HOWEVER ... that same scenario on a X3 sensor would produce a
PERFECT IMAGE of "RED" dots.

No.

The advantages are in better reproduced colour and lack of moiré
patterns in certain situations.

There is no real gain in sharpness or picture resolution.

The goal is to have improved sharpness and picture resolution.
Moire is a symptom of the undelrying problem Foveon is trying to
fix. It's not the problem.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

 

[Derek Clarke]

The point of the Foveon isn't increased resolution.

A 3Mpixel Foveon has 3 million pixels, not 6 and certainly not 9.

What it has got though is 3 million very colourful pixels!

But comparing it to a Bayer sensor with more pixels isn't fair. It is better colour and no moiré that we should be shouting about, not spurious resolution.

You are resonding to technical posts with technical posts. Fine.
This post is not meant as a critique of that.

But what I'd like to know is if we're comparing apples and oranges
or apples and apples.

Is there a realistic comparison possible? Is the Foveon chip equal
to a bayer chip twice it's size, 50 percent?

Is the fact that there are different implementations of the bayer
chip a problem and to what degree?

If you can make such a comparison let it be on the basis of the
best existing bayer pattern.

I don't mean to put you on the spot. Exisiting terminology and the
lay understanding of this is that when a camera is rated at 6MP
it's going to be twice as powerful as a 3MP. Along comes Foveon and
the exisiting ratings don't seem to mean much.

So my question really boils down to assigning ratings to chips that
will make some sense to the person going out to buy a camera.

Dave

No.

The advantages are in better reproduced colour and lack of moiré
patterns in certain situations.

There is no real gain in sharpness or picture resolution.

The goal is to have improved sharpness and picture resolution.
Moire is a symptom of the undelrying problem Foveon is trying to
fix. It's not the problem.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

--
Derek

 

[Derek Clarke]

The difference between colour interpolation and pixel interpolation seems to have escaped you.

The latter invents detail, the former just makes for muddier colour.

No.

The advantages are in better reproduced colour and lack of moiré
patterns in certain situations.

There is no real gain in sharpness or picture resolution.

YES ... there is the potential of DOUBLE the resolution AND
SHARPNESS of current 6mps senors.

Up to this point in this age of digital technology I found that all
things being equal go with more pixels if you want to print your
pictures larger. That is the reason I have a 6mp DSLR. So my 6mp
file is 3024x2016 if I want to print a 18x12in. (Epson 1280) my
printing resolution is 168 pixel/inch.... barely acceptable. So
here is the question, the Sigma Foveon is 2268x1512 so if I want to
print 18x12in. will be at 125pixels/inch. Will the Foveon X3 CMOS
produce a much better 18X12in. print compared to the present 6mp
DSLR?

Your "file" may be 3024x2016 ... but that is INTERPOLATED,
(guessed), data. You actual resolution/sharpness is only 1.5mps
... anything above that is a GUESS. (albeit an "educated" guess
... but still a guess)

If you interpolate the X3 file to 6mps ... it will also be a guess
... but TWICE AS ACCURATE since it had more than double the
original data to begin with.

Boris

--
Derek

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

--
Derek

 

[Ron Parr]

The point of the Foveon isn't increased resolution.

A 3Mpixel Foveon has 3 million pixels, not 6 and certainly not 9.

What it has got though is 3 million very colourful pixels!

But comparing it to a Bayer sensor with more pixels isn't fair. It
is better colour and no moiré that we should be shouting about, not
spurious resolution.

There's very little basis for believing that Foveon sensor will produce more accurate color across broad areas. Bayer pattern sensors already do this. The main place where you'll notice the difference is at the edges which, IMO, is the most important area.

Ultimately, it's a resolution argument not a color accuracy argument. Resolution and the perception of sharpness are the things to be excited about here and it's natural compare with 6MP Bayer pattern cameras b/c that's Foveon's competition.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

 

[Ron Parr]

The difference between colour interpolation and pixel interpolation
seems to have escaped you.

The latter invents detail, the former just makes for muddier colour.

No. Bayer interpolation invents detail too. There's not some kind of "detail" wave that hits the sensor and is recorded The perception of detail arises from the luminance, which is a function of red, green and blue. Each pixel only sees a fraction of the luminance because the filters block at least two of the colors.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

 

[David Barkin]

Hi All

I just downloaded one of the new samples that Phill posted. I downloaded the full sized version, although of course it was in JPEG and only 1.4 MB.

At any rate the image compared quite favoribly with the best of my shots with the D1x. Of course no one posts bad samples, so in and of itself this really doesn't mean to much. I then interpolated the image up, doubled it, and here the results were amazing. It was if I was looking at an original image not an interpolation.

Now I routinly interpolate up for printing at 16 x 20 and the results are just fine, but this was crystal clear, truly amazing.

Dave

 

[JoePhoto]

The point of the Foveon isn't increased resolution.

A 3Mpixel Foveon has 3 million pixels, not 6 and certainly not 9.

What it has got though is 3 million very colourful pixels!

When you were in third-grade and had an arithmitic test ... if the question was 3 X 3 = ??? What did you answer ????

The Foveon X3 has the "X3" for a reason. The reason is because it has 3.54 X 3 mps. It has 10.62mps.

Not 3, not 6 ... not 9 ... it has 10.62mps. (and an equivalent Bayer would require 14.16mps)

The only difference is they are STACKED instead of taking up extra room side-by-side. Is that so hard to understand ???

But comparing it to a Bayer sensor with more pixels isn't fair. It
is better colour and no moiré that we should be shouting about, not
spurious resolution.

You are resonding to technical posts with technical posts. Fine.
This post is not meant as a critique of that.

But what I'd like to know is if we're comparing apples and oranges
or apples and apples.

Is there a realistic comparison possible? Is the Foveon chip equal
to a bayer chip twice it's size, 50 percent?

Is the fact that there are different implementations of the bayer
chip a problem and to what degree?

If you can make such a comparison let it be on the basis of the
best existing bayer pattern.

I don't mean to put you on the spot. Exisiting terminology and the
lay understanding of this is that when a camera is rated at 6MP
it's going to be twice as powerful as a 3MP. Along comes Foveon and
the exisiting ratings don't seem to mean much.

So my question really boils down to assigning ratings to chips that
will make some sense to the person going out to buy a camera.

Dave

No.

The advantages are in better reproduced colour and lack of moiré
patterns in certain situations.

There is no real gain in sharpness or picture resolution.

The goal is to have improved sharpness and picture resolution.
Moire is a symptom of the undelrying problem Foveon is trying to
fix. It's not the problem.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

--
Derek

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

 

[JoePhoto]

I do NOT agree ... it is VERY EASY to make a "comparason" ... you
simply have to know if it is a R-G-B or R-G-B-B arrangement.

In the first case ... simply divide the mps rating by 3 ... and 4
if a RGBB.

It's really not that simple. You primarily notice detail in the
green channel and you're unlikely to notice any cheating in the
blue or red channel. This is why they use R-G-B-G pattern. Such a
pattern will look better to your eye than a simple R-G-B. That's
why they do it. These guys who make cameras aren't stupid, but
your reasoning above actually suggests that the mostly widely used
Bayer pattern will have lower apparent resolution than the simple
one.

In reality most of our perception of detail does come from the
green channel, so for most images the fact that half the pixels are
green will be sufficient to give the perception of around half the
stated resolution.

If I have my theoritical "white" wall with "red" dots/squares. I am only interested in how many "red" sensors there are.

Now you have the problem of interpolation. Yes, interpolation is
guessing information and it's impossible to be right all of the
time. However, it's also impossible to be wrong all of the time.
The actual performance is somewhere in the middle.

True .. but the same is true if you interpolate a X3 file to a higher density. The fact remains that there are only 1.5m "groups" of pixels able to produce "white" dots in a conventional 6mps sensor ... there are 3.54m of those same "groups" in X3.

THE ONLY DIFFERENCE IS THEY ARE STACKED INSTEAD OF SIDE-by-SIDE.

Finally, there are other issues like noise, etc. If there are
other sacrifices made to achieve an X3 solution, then some things
like noise could degrade the image and reduce any theoretical
benefit you might have hoped to achieve.

I'm not saying any of this discourage you on the X3 sensor. I'm
very excited about it and I'm mostly on the other side of these
arguments, trying to defend it against people who want to shoot it
down. In this particular case, however, I think you need to be
more realistic. It's a complicated system and there are many
factors.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

 

[JoePhoto]

The difference between colour interpolation and pixel interpolation
seems to have escaped you.

The latter invents detail, the former just makes for muddier colour.

I hope you are not saying you want to "invent" detail.

I am happy with an accurate "duplication" of the detail that already existed in the scene. Intertpolation "guesses" at that duplication. It has a 50-50 chance of being correct ... based on intelligence gleaned from surounding pixels. But the other 50% when it is wrong ... means it has "invented" something that was not there ... (artifacting).

And this is not mentioning MORIE (color-morie at least); that is virtually eliminated with the X3 concept.

No.

The advantages are in better reproduced colour and lack of moiré
patterns in certain situations.

There is no real gain in sharpness or picture resolution.

YES ... there is the potential of DOUBLE the resolution AND
SHARPNESS of current 6mps senors.

Up to this point in this age of digital technology I found that all
things being equal go with more pixels if you want to print your
pictures larger. That is the reason I have a 6mp DSLR. So my 6mp
file is 3024x2016 if I want to print a 18x12in. (Epson 1280) my
printing resolution is 168 pixel/inch.... barely acceptable. So
here is the question, the Sigma Foveon is 2268x1512 so if I want to
print 18x12in. will be at 125pixels/inch. Will the Foveon X3 CMOS
produce a much better 18X12in. print compared to the present 6mp
DSLR?

Your "file" may be 3024x2016 ... but that is INTERPOLATED,
(guessed), data. You actual resolution/sharpness is only 1.5mps
... anything above that is a GUESS. (albeit an "educated" guess
... but still a guess)

If you interpolate the X3 file to 6mps ... it will also be a guess
... but TWICE AS ACCURATE since it had more than double the
original data to begin with.

Boris

--
Derek

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )

--
Derek

--
Thanks for reading .... JoePhoto

( Do You Ever STOP to THINK --- and FORGET to START Again ??? )