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masuring overall sharpness of an image

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Anonymous
May 14, 2005 1:55:40 PM

Archived from groups: rec.photo.digital (More info?)

Hi!
I#m thinkong of replacing my coolpix 5000 by a dslr,
possibly the D50.
However, the coolpix had that nice "best shot" feature,
where you just pressed the button, the cam shot 7 pictures
and selected the sharpest one.
The D50 is missing that.
Is there any way I can quantify the sharpness of an image
so that I can, for instance, pick out the sharpest image
out of a series using photoshop or a similar tool?
Can one measure the sharpness and put it into a number?

Lots of Greetings!
Volker
Anonymous
May 14, 2005 1:55:41 PM

Archived from groups: rec.photo.digital (More info?)

Volker Hetzer wrote:
> Hi!
> I#m thinkong of replacing my coolpix 5000 by a dslr,
> possibly the D50.
> However, the coolpix had that nice "best shot" feature,
> where you just pressed the button, the cam shot 7 pictures
> and selected the sharpest one.
> The D50 is missing that.
> Is there any way I can quantify the sharpness of an image
> so that I can, for instance, pick out the sharpest image
> out of a series using photoshop or a similar tool?
> Can one measure the sharpness and put it into a number?
>
> Lots of Greetings!
> Volker

Volker, one thing you could try (and how I suspect the BSS feature of the
Nikon Coolpix range works), is to look for the JPEG image with the largest
file size. It should contain the most detail (all other things being
equal).

I recently "replaced" my Nikon 990 and 5700 by the Nikon 8400 (24mm wide
angle) and Panasonic FZ5 (432mm image stabilised zoom). I wouldn't want
to downgrade to a DSLR!

Cheers,
David
Anonymous
May 14, 2005 2:29:13 PM

Archived from groups: rec.photo.digital (More info?)

David J Taylor wrote:

> Volker, one thing you could try (and how I suspect the BSS feature of the
> Nikon Coolpix range works), is to look for the JPEG image with the largest
> file size. It should contain the most detail (all other things being
> equal).
Good idea.

>
> I recently "replaced" my Nikon 990 and 5700 by the Nikon 8400 (24mm wide
> angle) and Panasonic FZ5 (432mm image stabilised zoom). I wouldn't want
> to downgrade to a DSLR!
Hm. My 5000 has a nasty problem with sky noise. Basically, dark blue
sky in the mountains is simply not doable if I want images of 5x7 or
8x12 inch images. I was hoping to get rid of it with a dslr that has
hopefully a larger sensor for the same pixel count.
How does the 8400 hold its own with a deep blue sky and that type of
magnification?
If it weren't for that sky problem I'd really hold on to my cam.

Lots of Greetings!
Volker
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Anonymous
May 14, 2005 2:29:14 PM

Archived from groups: rec.photo.digital (More info?)

Volker Hetzer wrote:
[]
> Hm. My 5000 has a nasty problem with sky noise. Basically, dark blue
> sky in the mountains is simply not doable if I want images of 5x7 or
> 8x12 inch images. I was hoping to get rid of it with a dslr that has
> hopefully a larger sensor for the same pixel count.
> How does the 8400 hold its own with a deep blue sky and that type of
> magnification?
> If it weren't for that sky problem I'd really hold on to my cam.

I can't really comment as I don't have experience of those taking
circumstances. What sort of problem are you seeing? Too much JPEG
compression can show as banding in areas of near-uniform colour. Try
using RAW mode or less JPEG compression.

The Nikon Coolpix 8400 is two generations on from the 5000, so you can
expect that a number of things to have improved. For example, they have
added ultra-fine JPEG compression give a choice of four compression
levels. The angle of view is wider, and there is an addition autofocus
sensor for faster response. Can you borrow an 8400 to check it out?

Just getting a DSLR may not help - you may need to move to working with
RAW files as well.

Cheers,
David
Anonymous
May 14, 2005 4:00:07 PM

Archived from groups: rec.photo.digital (More info?)

David J Taylor wrote:
> Volker Hetzer wrote:
> []
>
>>Hm. My 5000 has a nasty problem with sky noise. Basically, dark blue
>>sky in the mountains is simply not doable if I want images of 5x7 or
>>8x12 inch images. I was hoping to get rid of it with a dslr that has
>>hopefully a larger sensor for the same pixel count.
>>How does the 8400 hold its own with a deep blue sky and that type of
>>magnification?
>>If it weren't for that sky problem I'd really hold on to my cam.
>
>
> I can't really comment as I don't have experience of those taking
> circumstances. What sort of problem are you seeing? Too much JPEG
> compression can show as banding in areas of near-uniform colour. Try
> using RAW mode or less JPEG compression.
Ok, I took shots in scotland with JPEG and "fine" compression, full size.
Basically the "best" jpeg mode available.
Image quality was great no visible pixels at 8x12 inches but the sky
showed fuzzy blobs in the millimetre range all over the sky.
http://service.gmx.net/mc/xvxjJYZE734RUe3xndH0JVeLSwIpg... shows an example.
(just press "GMX Mediacenter starten")
It's not that visible on a monitor but shows up very much on a large print.
I've seen 2MP cameras with less noise in comparable image parts.

Next time I'll definitely use raw for images with sky, to eliminate
at least the jpeg influence. Maybe then it becomes true pixel noise
and is easier to deal with with neatimage or so.

>
> The Nikon Coolpix 8400 is two generations on from the 5000, so you can
> expect that a number of things to have improved. For example, they have
> added ultra-fine JPEG compression give a choice of four compression
> levels. The angle of view is wider, and there is an addition autofocus
> sensor for faster response. Can you borrow an 8400 to check it out?
I think so. I just have to wait for the right weather.


Lots of Greetings and Thanks!
Volker
Anonymous
May 14, 2005 4:00:08 PM

Archived from groups: rec.photo.digital (More info?)

Volker Hetzer wrote:
[]
> Ok, I took shots in scotland with JPEG and "fine" compression, full
> size. Basically the "best" jpeg mode available.
> Image quality was great no visible pixels at 8x12 inches but the sky
> showed fuzzy blobs in the millimetre range all over the sky.
> http://service.gmx.net/mc/xvxjJYZE734RUe3xndH0JVeLSwIpg... shows an
> example. (just press "GMX Mediacenter starten")
> It's not that visible on a monitor but shows up very much on a large
> print. I've seen 2MP cameras with less noise in comparable image
> parts.
> Next time I'll definitely use raw for images with sky, to eliminate
> at least the jpeg influence. Maybe then it becomes true pixel noise
> and is easier to deal with with neatimage or so.

That looks more like JPEG compression noise (resampled to the image size
you have). Full size and fine compression should give you the best
quality. I've been using Normal compression with the 8400, so for
interest I'll e-mail you a similar picture taken recently. Spain, not
Scotland, although we have had some similar blue skies recently!

Cheers,
David
Anonymous
May 14, 2005 6:58:22 PM

Archived from groups: rec.photo.digital (More info?)

David J Taylor wrote:

> That looks more like JPEG compression noise (resampled to the image size
> you have). Full size and fine compression should give you the best
> quality. I've been using Normal compression with the 8400, so for
> interest I'll e-mail you a similar picture taken recently. Spain, not
> Scotland, although we have had some similar blue skies recently!
I've sent it off for printing.

Thanks a lot for the info and the reference picture!
Volker
May 15, 2005 4:38:03 AM

Archived from groups: rec.photo.digital (More info?)

Volker Hetzer wrote:

> David J Taylor wrote:
>
>> Volker, one thing you could try (and how I suspect the BSS feature of
>> the Nikon Coolpix range works), is to look for the JPEG image with the
>> largest file size. It should contain the most detail (all other
>> things being equal).
>
> Good idea.
>
>>
>> I recently "replaced" my Nikon 990 and 5700 by the Nikon 8400 (24mm
>> wide angle) and Panasonic FZ5 (432mm image stabilised zoom). I
>> wouldn't want to downgrade to a DSLR!
>
> Hm. My 5000 has a nasty problem with sky noise. Basically, dark blue
> sky in the mountains is simply not doable if I want images of 5x7 or
> 8x12 inch images. I was hoping to get rid of it with a dslr that has
> hopefully a larger sensor for the same pixel count.
> How does the 8400 hold its own with a deep blue sky and that type of
> magnification?
> If it weren't for that sky problem I'd really hold on to my cam.
>
> Lots of Greetings!
> Volker


The problems with noise in sky shots won't be just a bit better with a
DSLR, they will be much much better.
That said, in daylight you should still be able to get acceptable
results - and it looks like you aren't. To get the best result, you
must set the camera ISO setting to minimum, maybe ISO 50. This probably
means overriding auto settings. Also make sure image
quality/compression is set to best quality.
Other posters have suggested that with a DSLR you must use RAW image
tools. This is certainly not the case - in fact unless you know what
you are doing, the reverse may be true. High quality jpg's directly
from the camera (in the case of a D70 and assumably a D50) show no
significant noise in sky shots at ISO 400, and _none_ at ISO 200. Canon
DSLR cameras are even better in regard to noise, and go down to ISO 100.
Anonymous
May 15, 2005 4:38:04 AM

Archived from groups: rec.photo.digital (More info?)

Frederick wrote:

> The problems with noise in sky shots won't be just a bit better with a
> DSLR, they will be much much better.
> That said, in daylight you should still be able to get acceptable
> results - and it looks like you aren't. To get the best result, you
> must set the camera ISO setting to minimum, maybe ISO 50. This probably
> means overriding auto settings. Also make sure image
> quality/compression is set to best quality.
Yep, that I did. After getting Davids nice 8400 shot I'm going
to get another coolpix 5000 shot with a different camera from the shop.
Thing is, I already sent my camera in for service (advice of my photo
print guy) and the results (as far as I can see in normal circumstances)
aren't better. Maybe they didn't do much because it was still on warranty.
So, if I get a side by side comparison maybe then I can get Nikon to do
something serious, like changing the sensor or giving me a new camera.

> Other posters have suggested that with a DSLR you must use RAW image
> tools. This is certainly not the case - in fact unless you know what
> you are doing, the reverse may be true. High quality jpg's directly
> from the camera (in the case of a D70 and assumably a D50) show no
> significant noise in sky shots at ISO 400, and _none_ at ISO 200. Canon
> DSLR cameras are even better in regard to noise, and go down to ISO 100.
Hm. The idea behind raw is probably that the compression of a wide almost
uniform area may excerberate the problem. But this is just off my head
and the next day with good sky (in germany that can take a while) will
see me out doing lots of test images.

Lots of Greetings and Thanks!
Volker
Anonymous
May 15, 2005 4:38:05 AM

Archived from groups: rec.photo.digital (More info?)

Volker Hetzer wrote:
> Frederick wrote:
[]
>> Other posters have suggested that with a DSLR you must use RAW image
>> tools. This is certainly not the case - in fact unless you know what
>> you are doing, the reverse may be true. High quality jpg's directly
>> from the camera (in the case of a D70 and assumably a D50) show no
>> significant noise in sky shots at ISO 400, and _none_ at ISO 200. Canon
>> DSLR cameras are even better in regard to noise, and go down
>> to ISO 100.
> Hm. The idea behind raw is probably that the compression of a wide
> almost uniform area may excerberate the problem. But this is just off
> my head and the next day with good sky (in germany that can take a
> while) will see me out doing lots of test images.
>
> Lots of Greetings and Thanks!
> Volker

Properly done, RAW should bypass the artefacts due to JPEG compression,
and allow a more accurate evaluation of the sensor and electronics. You
are certainly right to try your own tests, as what is acceptable to some
is objectionable to others - it's a subjective judgement you are making.

Cheers,
David
Anonymous
May 15, 2005 4:38:06 AM

Archived from groups: rec.photo.digital (More info?)

David J Taylor wrote:
> Properly done, RAW should bypass the artefacts due to JPEG compression,
> and allow a more accurate evaluation of the sensor and electronics. You
> are certainly right to try your own tests, as what is acceptable to some
> is objectionable to others - it's a subjective judgement you are making.
>
> Cheers,
> David

I can remember when I used to do a lot of darkroom work, there were
TEXTURE screens available to sandwich with the printing paper. One was
"grain". It simulated a large grain very fast film. People would pay
good money to get this effect! So, yeah, it is SO true that what is
acceptable to some is objectionable to others. Unless you are shooting
strictly record snapshots, beauty is indeed in the eye of the beholder.
!