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8MP vs. 5MP

 
 
Alfred Molon
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      02-14-2004
Since the new 2/3" 8MP CCD has pixels of the same size as a 1/1.8" 5MP
CCD, noise should be more or less the same, shouldn't it ?

In other words an 8MP camera with a 2/3" CCD should have the same noise
level as the current generation of 5MP digital cameras with a 1/1.8"
CCD.

Or could it be the case that at 8MP the lenses cannot keep up with the
increased resolution and as a consequence the camera has to sharpen a
lot internally, thereby amplifying noise ?
--

Alfred Molon
------------------------------
http://groups.yahoo.com/group/Olympus_405060/
Olympus 5050 resource - http://www.molon.de/5050.html
Olympus 5060 resource - http://www.molon.de/5060.html
 
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Kevin McMurtrie
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      02-15-2004
In article <(E-Mail Removed) .com>,
Alfred Molon <(E-Mail Removed)> wrote:

> Since the new 2/3" 8MP CCD has pixels of the same size as a 1/1.8" 5MP
> CCD, noise should be more or less the same, shouldn't it ?
>
> In other words an 8MP camera with a 2/3" CCD should have the same noise
> level as the current generation of 5MP digital cameras with a 1/1.8"
> CCD.
>
> Or could it be the case that at 8MP the lenses cannot keep up with the
> increased resolution and as a consequence the camera has to sharpen a
> lot internally, thereby amplifying noise ?


Any of the above can be true, or not. You'll just have to check the
reviews and sample photos.
 
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Mark Herring
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      02-15-2004
On Sat, 14 Feb 2004 23:39:22 GMT, Alfred Molon
<(E-Mail Removed)> wrote:

>Since the new 2/3" 8MP CCD has pixels of the same size as a 1/1.8" 5MP
>CCD, noise should be more or less the same, shouldn't it ?

Yes, assuming the same optics and other factors
>
>In other words an 8MP camera with a 2/3" CCD should have the same noise
>level as the current generation of 5MP digital cameras with a 1/1.8"
>CCD.

but worse than a 2/3" 5Mp sensor
>
>Or could it be the case that at 8MP the lenses cannot keep up with the
>increased resolution and as a consequence the camera has to sharpen a
>lot internally, thereby amplifying noise ?

No---noise is tied to the system gain and the size of the
pixel----processing does not change the intrinsic signal to noise
ratio.

**************************
Mark Herring, Pasadena, Calif.
Private e-mail: Just say no to "No".

 
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Alfred Molon
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      02-15-2004
In article <(E-Mail Removed)>, http://www.velocityreviews.com/forums/(E-Mail Removed) says...

> >Or could it be the case that at 8MP the lenses cannot keep up with the
> >increased resolution and as a consequence the camera has to sharpen a
> >lot internally, thereby amplifying noise ?

> No---noise is tied to the system gain and the size of the
> pixel----processing does not change the intrinsic signal to noise
> ratio.


I would have thought that a not so sharp lens could be compensated by
additional sharpening (via software) in the camera.
--

Alfred Molon
------------------------------
http://groups.yahoo.com/group/Olympus_405060/
Olympus 5050 resource - http://www.molon.de/5050.html
Olympus 5060 resource - http://www.molon.de/5060.html
 
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David J Taylor
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      02-15-2004
> I would have thought that a not so sharp lens could be compensated by
> additional sharpening (via software) in the camera.
> --
>
> Alfred Molon


I would have thought it better to keep the lens-related sharpening the
same.

Then with 8MP you get more samples across the image, making for:

- a higher spatial frequency noise, and therefore less visible noise
(measured at the same viewing angle)

- fewer JPEG artefacts for a given compression ratio, given that there is
a greater pixel-to-pixel correlation.

Cheers,
David


 
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JPS@no.komm
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      02-15-2004
In message <(E-Mail Removed) .com>,
Alfred Molon <(E-Mail Removed)> wrote:

>I would have thought that a not so sharp lens could be compensated by
>additional sharpening (via software) in the camera.


If you use sharpening to bring back some of the detail rolled off by the
AA filter, or the limits of the lens if it is the limiting factor, but
sharpening an out-of focus or motion-blurred image usually looks
artificial to me. The worst looking USM you see is usually stuff in the
1.5 to 10 pixel range; that is the range that I have never found any use
for. I generally use 0.3 to 0.7, or something big like 25.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <(E-Mail Removed)>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><

 
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Mark Herring
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      02-15-2004
On Sun, 15 Feb 2004 08:58:50 GMT, Alfred Molon
<(E-Mail Removed)> wrote:

>In article <(E-Mail Removed)>, (E-Mail Removed) says...
>
>> >Or could it be the case that at 8MP the lenses cannot keep up with the
>> >increased resolution and as a consequence the camera has to sharpen a
>> >lot internally, thereby amplifying noise ?

>> No---noise is tied to the system gain and the size of the
>> pixel----processing does not change the intrinsic signal to noise
>> ratio.

>
>I would have thought that a not so sharp lens could be compensated by
>additional sharpening (via software) in the camera.

Correct---but this does not increase noise
**************************
Mark Herring, Pasadena, Calif.
Private e-mail: Just say no to "No".

 
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Andrew Koenig
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      02-15-2004
"Alfred Molon" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) news.com...

> Since the new 2/3" 8MP CCD has pixels of the same size as a 1/1.8" 5MP
> CCD, noise should be more or less the same, shouldn't it ?


> In other words an 8MP camera with a 2/3" CCD should have the same noise
> level as the current generation of 5MP digital cameras with a 1/1.8"
> CCD.


Not in the way one normally thinks of it. The total amount of thermal noise
would be the same, but the signal is divided up among more pixels. The
noise is therefore averaged over a smaller area for each pixel and has a
relatively greater effect.

All other things being equal (which they rarely are), increasing the number
of pixels will increase both resolution and noise. A similar phenomenon
occurs in development of black-and-white film: Increasing developer
dilution often increases sharpness and also increases grain.


 
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Alfred Molon
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      02-15-2004
In article <(E-Mail Removed)>,
(E-Mail Removed) says...
> >> >Or could it be the case that at 8MP the lenses cannot keep up with the
> >> >increased resolution and as a consequence the camera has to sharpen a
> >> >lot internally, thereby amplifying noise ?
> >> No---noise is tied to the system gain and the size of the
> >> pixel----processing does not change the intrinsic signal to noise
> >> ratio.

> >
> >I would have thought that a not so sharp lens could be compensated by
> >additional sharpening (via software) in the camera.

> Correct---but this does not increase noise


It does - any sharpening increases noise.
--

Alfred Molon
------------------------------
http://groups.yahoo.com/group/Olympus_405060/
Olympus 5050 resource - http://www.molon.de/5050.html
Olympus 5060 resource - http://www.molon.de/5060.html
 
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Bart van der Wolf
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      02-15-2004

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> In message <(E-Mail Removed) .com>,
> Alfred Molon <(E-Mail Removed)> wrote:
>
> >I would have thought that a not so sharp lens could be compensated by
> >additional sharpening (via software) in the camera.

>
> If you use sharpening to bring back some of the detail rolled off by the
> AA filter, or the limits of the lens if it is the limiting factor, but
> sharpening an out-of focus or motion-blurred image usually looks
> artificial to me.


Yes, although there are techniques that work better than a simple USM.
Deconvolution (in Fourier space) will recover some of the original
sharpness, although there are limits to what can be done.

> The worst looking USM you see is usually stuff in the
> 1.5 to 10 pixel range; that is the range that I have never found any use
> for. I generally use 0.3 to 0.7, or something big like 25.


Yes those are the ranges I also use most on the final image size. Sharpening
for print can be a bit stronger to compensate for additional losses.

Bart


 
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