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Possible to extract high resolution b/w from a raw file?

 
 
Bruce
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      05-10-2011
On Tue, 10 May 2011 06:37:49 -0700, Paul Furman <(E-Mail Removed)>
wrote:
>bob wrote:
>> Is it possible to to extract a b/w photo from a camera raw file that is
>> higher resolution than the color version, since one color pixel is made
>> up of 4 b/w pixels with color filters?

>
>You'd need a sensor with no Bayer color filter, and even then you'd need
>to remove the antialiasing filter, then risk moire patterns.



The risk of moire is hugely overstated. I shoot with a 14 MP Kodak
DCS Pro 14n full frame DSLR and a 39 MP Hasselblad. Both have Kodak
sensors with no AA filters. Moire isn't a significant problem for me.
I can think of a lot of systematic flaws in images that occur much
more frequently than moire. Moire is something that troubles armchair
"experts" far more than it troubles working photographers.

If moire really was a problem, everyone would be using AA filters all
the time. The reality is that the sharpness of images rendered
without AA filters is very attractive, especially among fashion
photographers. Yet fashion is the genre most likely to have problems
with moire because of woven fabrics! Go figure ...

P.S. It is also worth pointing out that Nikon (and some other
manufacturers) have installed weaker AA filters with each new
generation of their digital SLRs. The result is that Nikon's sensors
now significantly outperform Canon's in terms of image sharpness
before post-processing is applied.

Nevertheless my 14 MP Kodak 14n (from 2004!) still outperforms my
Nikon D3 by a worthwhile margin at base ISO. It should probably be in
a museum, and has many flaws, but the image quality still takes my
breath away. Dynamic range is very good indeed and the natural colour
rendition is better than that of any other DSLR I have used. It's a
pity Kodak didn't develop it further. The 39 MP Kodak sensor in the
Hasselblad is also excellent - and that's another camera that's far
from being the latest model!

 
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nospam
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      05-10-2011
In article <(E-Mail Removed)>, Bruce
<(E-Mail Removed)> wrote:

> The risk of moire is hugely overstated. I shoot with a 14 MP Kodak
> DCS Pro 14n full frame DSLR and a 39 MP Hasselblad. Both have Kodak
> sensors with no AA filters. Moire isn't a significant problem for me.
> I can think of a lot of systematic flaws in images that occur much
> more frequently than moire. Moire is something that troubles armchair
> "experts" far more than it troubles working photographers.


the 'italian flag syndrome' is very common with the kodak slrs.

> If moire really was a problem, everyone would be using AA filters all
> the time.


and in fact, they are. almost every digital camera has an antialias
filter, the main exception being sigma.

> The reality is that the sharpness of images rendered
> without AA filters is very attractive, especially among fashion
> photographers. Yet fashion is the genre most likely to have problems
> with moire because of woven fabrics! Go figure ...


attractive to some, ugly to others.

> P.S. It is also worth pointing out that Nikon (and some other
> manufacturers) have installed weaker AA filters with each new
> generation of their digital SLRs.


actually nikon's aa filters have been getting stronger. the d70 was
weak and exhibited colour fringing and recent cameras are noticeably
stronger to minimize that.

> The result is that Nikon's sensors
> now significantly outperform Canon's in terms of image sharpness
> before post-processing is applied.


for other reasons.

> Nevertheless my 14 MP Kodak 14n (from 2004!) still outperforms my
> Nikon D3 by a worthwhile margin at base ISO.


bullshit. it's not even in the same league. the 14n had a very noisy
sensor and topped out at iso 400. it also had a 12 bit a/d converter so
it *can't* outperform the d3.

> It should probably be in
> a museum, and has many flaws, but the image quality still takes my
> breath away. Dynamic range is very good indeed and the natural colour
> rendition is better than that of any other DSLR I have used.


it is not wider than a nikon d3 or a fuji s5, or most modern dslrs. it
was actually not very good.
 
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Bruce
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      05-10-2011
On Tue, 10 May 2011 10:34:00 -0400, shiva das <(E-Mail Removed)>
wrote:
>In article <(E-Mail Removed)>,
> Bruce <(E-Mail Removed)> wrote:
>
>> Mxsmanic <(E-Mail Removed)> wrote:
>> >bob writes:
>> >
>> >> Is it possible to to extract a b/w photo from a camera raw file that is
>> >> higher resolution than the color version, since one color pixel is made up
>> >> of 4 b/w pixels with color filters?
>> >
>> >No. The limit of luminance resolution doesn't change. All you're doing with
>> >black and white is removing the color information, but no new information is
>> >added. You can get the same black-and-white resolution by simply removing the
>> >color from the image.
>> >
>> >If you could physically remove the filters from the photosites on the sensor,
>> >then you could get better luminance resolution, at the expense of eliminating
>> >all color resolution entirely.

>>
>>
>> I often wonder why no manufacturer offers a b/w digital SLR or digital
>> rangefinder camera (yes, Leica Camera, that's you!). I think it would
>> be a strong seller to a niche market.
>>
>> In the meantime, I am very satisfied with ADOX CM 20 film, which
>> probably has about the best resolving power of any currently available
>> photographic medium:
>>
>> http://www.adox.de/english/ADOX_Films/ADOX_Films.html

>
>Phase One makes a monochrome back for medium format cameras, "the
>Achromatic+ digital back", 39MP, which does not have a color filter.
>
>"The Phase One Achromatic+ is available for the Mamiya 645 AFD
>(including the Phase One 645DF camera), Contax 645 and Hasselblad V
>interfaces.
>
>"Also available is the Phase One Achromatic+ for Hasselblad H1 and H2
>cameras.
>
>"The Achromatic+ can be ordered without an IR filter mounted
>permanently. There are multiple solutions available for working with
>interchangeable filters for such a solution."
>
><http://www.phaseone.com/en/Digital-Backs/Achromatic/Achromatic-plus-Info.aspx>



That back has been advertised for some time but in spite of knowing
quite a few digital medium format shooters I don't know anyone who has
bought one. None of the top three PhaseOne resellers in the UK has
one available.

The use of interchangeable digital backs is rapidly dying out in any
case, as is their use on medium format film SLRs. The trend is
strongly towards integrated medium format DSLRs with Hasselblad having
the majority of the market, at least here in Europe.

I would be keen to try a monochrome sensor but my Hassy is an H3 and
won't take an interchangeable back.

I get the impression that the Achromatic+ has perhaps been left
behind.

 
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nospam
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      05-10-2011
In article <(E-Mail Removed)>, Rich
<(E-Mail Removed)> wrote:

> > it makes a lot more sense to use a standard sensor and convert to b/w
> > when you want it, without giving up the ability to shoot colour when
> > you don't. it's also substantially less expensive, since low volume
> > sensors are not cheap.

>
> Not really.


yes really.

> Notice cutting edge scientific photography (astronomy, etc)
> still rely on monochrome CCDs. They do tri-colour filtration to create
> colour images when they need it. That way, no resolution or sharpness is
> lost due to Bayer filteration.


good luck if your subject moves. how many of those do you see in a
camera store? zero. can you say irrelevant?
 
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Bruce
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      05-10-2011
On Tue, 10 May 2011 18:11:04 -0500, Rich <(E-Mail Removed)> wrote:
>Kodak CCD's are inherently superior to consumer CMOS (that's ALL Nikons,
>Canons, etc) except in two key areas: Visible noise and power
>consumption. That is what killed them.



I'm sorry to have to tell you that my Kodak DCS Pro 14n has a CMOS
sensor, and that Kodak CCD sales to manufacturers such as Pentax,
Hasselblad and Leica are thriving!

But thank you for making me smile. I've just finished shooting a
corporate event at London's South Bank. I'm tired and even more
irritable than usual, and I'm having to wait until proofs of every
shot taken are printed off, approved by the client and handed over.

It's been a long night and at 12.32 AM it is still far from over!

 
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Martin Brown
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      05-11-2011
On 10/05/2011 21:19, nospam wrote:
> In article<sngyp.71716$(E-Mail Removed)>, Martin Brown
> <|||newspam|||@nezumi.demon.co.uk> wrote:
>
>>>> Actually, the minimum number of sensor locations that
>>>> could be used per pixel is 4,
>>>
>>> actually, it's 5: the pixel itself plus the 4 direct neighbors (up,
>>> down, left, right). i don't know of anything that does that, since it
>>> looks like ****. normally 9 is considered the minimum.

>>
>> Actually he is right that a matrix of 4 cells is the bare minimum that
>> can be used for Bayer demosaic although the results are not great.

>
> right, the results are awful and also very low resolution. no bayer
> camera uses 2x2 blocks. it's stupid and a straw man.


The resolution is the same as the original sensor. You can always select
a boxcar of 4x4 sensor sites comprising GRBG in some permutation.
>
>> The pattern of 5 you describe fails completely for all red and blue
>> sensor sites which in the standard Bayer mosaic have only green direct
>> neighbours. At least Floyds method would allocate full RGB pixels to
>> every location on the grid apart from at the very edges.

>
> i wouldn't say fail completely. green is the main component of
> luminance (and in the original bayer patent, only green was
> considered). the colour errors will be high but the eye isn't that
> sensitive to that.


Fail completely in that half your reconstructed pixels are completely
missing any blue or red channel information. You don't understand what
you are talking about.

The colour fringing of diagonal sharp luminance transitions on Bayer are
awful if you do not handle them correctly. And the correct solution is
approximately to choose the most appropriate self consistent 4x4 pixel
block based on the crude estimated luminance values.
>
> a realistic minimum is 9 pixels. yes you 'can' do it with less but
> nobody does.
>
>> RG
>> GB
>>
>> Is the unit cell of the Bayer sensor grid.

>
> nobody uses 2x2, except in the minds of some foveon fanbois thinking
> that's how bayer works (it doesn't).


The practical implementations all use (at least) the 9x9 block centred
on the home cell but they can and do select different subset strategies
to avoid bleeding spurious colour into sharp white to black transitions.

Regards,
Martin Brown
 
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Wolfgang Weisselberg
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      05-11-2011
Floyd L. Davidson <(E-Mail Removed)> wrote:
> Wolfgang Weisselberg <(E-Mail Removed)> wrote:
>>bob <(E-Mail Removed)> wrote:


>>> since one color pixel is made up
>>> of 4 b/w pixels with color filters?


>>It is not.


> It is.


"bob"s description --- and your agreement --- can be read as "for
every 4 bayer sensors, there is one resulting colour pixel, i.e. a
10 MPix resulting image needs 40 million bayer sensor cells".
Which, as you know, is untrue.


> And even your description below says that it is.


Nope. Difference between "neighbours" and "made up of".
Difference between "4" and "neighbours".

> Actually, the minimum number of sensor locations that
> could be used per pixel is 4,


3. One red, one blue, one green.

> and in fact what actually
> is used will be a matrix of at least 9 sensor locations
> (and maybe more than that). They *all* contribute to
> the RGB values for a pixel produced by interpolation.


What I said.

-Wolfgang
 
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nospam
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      05-12-2011
In article <(E-Mail Removed)>, Mxsmanic
<(E-Mail Removed)> wrote:

> > good luck if your subject moves.

>
> Stars rarely move during an exposure.


unless you have a rotating platform that syncs with the earth, they do,
and what if you want to take pictures of other stuff?
 
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Bruce
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      05-12-2011
Mxsmanic <(E-Mail Removed)> wrote:
>Bruce writes:
>> I often wonder why no manufacturer offers a b/w digital SLR or digital
>> rangefinder camera (yes, Leica Camera, that's you!). I think it would
>> be a strong seller to a niche market.

>
>I agree. Kodak had one, I think, but it's gone now. Just converting color to
>black and white is not the same thing.



Kodak made the DCS Pro 760m b/w DSLR which was based on the Nikon F5
and had a 6 MP CCD. Two pro shooters told me that the 760m never
seemed to be available, and they don't know of anyone who actually
managed to buy one. For some of the reasons why, read this review of
the DCS 760m on the Luminous Landscape web site:

http://www.luminous-landscape.com/re...dak-760m.shtml

There was apparently going to be a b/w version of either the 14 MP
Kodak DCS Pro 14n or later SLR/n, but it never appeared.

 
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RichA
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      05-12-2011
On May 10, 7:33*pm, Bruce <(E-Mail Removed)> wrote:
> On Tue, 10 May 2011 18:11:04 -0500, Rich <(E-Mail Removed)> wrote:
> >Kodak CCD's are inherently superior to consumer CMOS (that's ALL Nikons,
> >Canons, etc) except in two key areas: *Visible noise and power
> >consumption. That is what killed them.

>
> I'm sorry to have to tell you that my Kodak DCS Pro 14n has a CMOS
> sensor, and that Kodak CCD sales to manufacturers such as Pentax,
> Hasselblad and Leica are thriving! *
>


The sensors in those camera are to the ones in the Hasselblad as the
D3 image is to a D40, one's a pro image, the other sports cartoon
colours designed to please soccer moms. Everything in the Hasselblad
back is higher grade, including the sensor, when it comes to critical
accuracy of things like colour. That is why Kodak (and Dalsa) sensors
dominate the science fields while Canon and Sony are no where to be
seen except in the least-demanding applications, like surveillance and
other related work.
 
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