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Lowering the resolution to improve quality

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Anonymous
January 3, 2005 12:54:04 AM

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

Hello everyone,

I own a Canon Powershot A70 (3.2 Megapixel) digital camera and I'm
trying to come up with images that have as low of a noise level as
possible.

I strive to take my shots with a low ISO setting, use flash as best as
I can, etc.

I've been taking all of my pictures at a reslution of 2048 by 1536.

My friend claims that I could reduce noise levels even further if I
lowered the resolution of my images; say down to 1600 by 1200.

Since I don't have access to my camera right now, I wonder if any of
you can elaborate on the topic. Does lowering the resolution lower the
noise level?

I wish I could just try it out and see for myself right now.
Thanks for all/any responses you may have.

- VR
Anonymous
January 3, 2005 1:37:49 AM

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

Thanks for the quick reply, Ken.

My friend explained that interpolation may be what's causing the noise
in my photos, and thus suggested that I "lower the resolution."

While I'm not too well informed about interpolation, I'll try Neat
Image again -- I've used it before -- and maybe even try the resolution
idea. I guess it doesn't hurt to try!
Again, thanks for your swift response.

VR
Anonymous
January 3, 2005 2:38:20 AM

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

"Eric Gill" <ericvgill@yahoo.com> schrieb
> "VR" <vroric@gmail.com> wrote
>> My friend explained that interpolation may be what's causing the noise
>> in my photos, and thus suggested that I "lower the resolution."
>
> Perhaps you misunderstood him. While downsampling does smooth the image -
> by blurring it, basically - you also lose information you need for
> printing
> at decent sizes.
Think so too, interpolation never causes noise. Real noise is a random
pattern.
But downsampling depends on the filter. A gaussian filter for example
creates a more blurred image while a sinc based filter is pretty sharp.

--
Regards
Jürgen
http://cpicture.de/en
Related resources
Anonymous
January 3, 2005 4:45:30 AM

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

VR wrote:
> Hello everyone,
>
> I own a Canon Powershot A70 (3.2 Megapixel) digital camera and I'm
> trying to come up with images that have as low of a noise level as
> possible.
>
> I strive to take my shots with a low ISO setting, use flash as best as
> I can, etc.
>
> I've been taking all of my pictures at a reslution of 2048 by 1536.
>
> My friend claims that I could reduce noise levels even further if I
> lowered the resolution of my images; say down to 1600 by 1200.
>
> Since I don't have access to my camera right now, I wonder if any of
> you can elaborate on the topic. Does lowering the resolution lower the
> noise level?
>
> I wish I could just try it out and see for myself right now.
> Thanks for all/any responses you may have.
>
> - VR
>

First, shooting at lower resolution will NOT decrease your noise level.
Your camera CAPTURES images at 2048x1536 pixels regardless of how you
save them. If you SAVE at 1600 x 1200 pixels, the camera will do the
downsampling before it saves the image to memory. But once the
downsampling is done, the discarded information cannot be recovered. If
you SAVE the image at 2048 x 1536 pixels you can always downsample in
your photo editor. But you will have the best image your camera can
produce. You will need all those pixels if you ever want to print an
8x10 at high quality.
If your camera permits, (I'm sure it does) you CAN reduce your noise
level by choosing the lowest ISO rating for your shots. This number is
typically 50 or 100.
But when using low ISO numbers you must have a decent amount of light to
get a good picture.

Think of the ISO setting exactly the way you would when selecting film.
ISO 50 = finest grain (lowest noise) for bright sunny days.
ISO 100 = slight grain for average cloudy bright days
ISO 200 = coarser grain for cloudy days.
ISO 400 = coarser grain for overcast days .
ISO 800 etc...
Bob Williams
Anonymous
January 3, 2005 4:53:39 AM

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

No, no... I didn't mean "shoot at 2048 x 1536 and then downsample the
image with software." I was saying "shoot at a lower resolution right
away." But I suppose that's not gonna improve my images.

Eric, I'm using the "Superfine" quality setting.

http://img.photobucket.com/albums/v487/vr044/IMG_0025.j...
This is a shot of my dog I did a few days back. Notice the noise around
the puppy's ear? (That's where it's very visible.) This is also not the
original resolution. (It was taken in 2048 x 1536 -- the posted image
is 1024 by 768).

I'm a pretty lame rookie photographer and am just getting into the
whole digital stuff. I always try to get the best pictures using the
"manual settings" that the camera lets you set on your own, yet people
tell me the "Auto" usually works best.
I don't know, I guess I'll learn as I go!

VR
Anonymous
January 3, 2005 4:57:07 AM

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

Bob, what would I use for an image that I want to shoot indoors at
night with somewhat direct, yet soft lighting?
Anonymous
January 3, 2005 9:16:35 AM

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

VR wrote:
> Hello everyone,
>
> I own a Canon Powershot A70 (3.2 Megapixel) digital camera and I'm
> trying to come up with images that have as low of a noise level as
> possible.
>
> I strive to take my shots with a low ISO setting, use flash as best as
> I can, etc.
>
> I've been taking all of my pictures at a reslution of 2048 by 1536.
>
> My friend claims that I could reduce noise levels even further if I
> lowered the resolution of my images; say down to 1600 by 1200.
>
> Since I don't have access to my camera right now, I wonder if any of
> you can elaborate on the topic. Does lowering the resolution lower the
> noise level?
>
> I wish I could just try it out and see for myself right now.
> Thanks for all/any responses you may have.
>


Hi...

With all due respect, your friend is terribly misguided.

Do the best you can, with your current size images. If
absolutely necessary clean up afterwards with Noise Ninja
or Neat Image.

Take care.

Ken
Anonymous
January 3, 2005 1:22:59 PM

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

VR wrote:

> Bob, what would I use for an image that I want to shoot indoors at
> night with somewhat direct, yet soft lighting?
>

A classical SLR with a very fast lens and 1600 ASA film possibly push
processed to 3200 ASA.

PS you can usually hide some of your noise by selectively blurring the
blue channel. It is worrying that your half sized dog image still shows
quite a bit of noise - could be your software has a poor choice of
downsampling algorithm or the original was underexposed and taken in
very poor light. Try using the camera in automatic mode for a while.

Averaging over 4 pixels (or alternatively median filtering) will
disguise the noise but you will lose resolution too.

Regards,
Martin Brown
Anonymous
January 3, 2005 2:51:16 PM

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

VR wrote:
> No, no... I didn't mean "shoot at 2048 x 1536 and then downsample the
> image with software." I was saying "shoot at a lower resolution right
> away." But I suppose that's not gonna improve my images.
>

You can't change how the camera records the image. What you are doing
is changing the way the camera saves the image. It will downsample it as it
saves it.


> Eric, I'm using the "Superfine" quality setting.
>
> http://img.photobucket.com/albums/v487/vr044/IMG_0025.j...
> This is a shot of my dog I did a few days back. Notice the noise
> around the puppy's ear? (That's where it's very visible.) This is
> also not the original resolution. (It was taken in 2048 x 1536 -- the
> posted image is 1024 by 768).
>
> I'm a pretty lame rookie photographer and am just getting into the
> whole digital stuff. I always try to get the best pictures using the
> "manual settings" that the camera lets you set on your own, yet people
> tell me the "Auto" usually works best.
> I don't know, I guess I'll learn as I go!
>
> VR

--
Joseph Meehan

26 + 6 = 1 It's Irish Math
Anonymous
January 3, 2005 7:43:21 PM

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

"VR" <vroric@gmail.com> wrote in news:1104746019.150738.104860
@z14g2000cwz.googlegroups.com:

> No, no... I didn't mean "shoot at 2048 x 1536 and then downsample the
> image with software." I was saying "shoot at a lower resolution right
> away." But I suppose that's not gonna improve my images.

Generally not - most cameras are downsampling when they do so.

> Eric, I'm using the "Superfine" quality setting.

Got it. Not an issue, then.

> http://img.photobucket.com/albums/v487/vr044/IMG_0025.j...
> This is a shot of my dog I did a few days back. Notice the noise around
> the puppy's ear? (That's where it's very visible.) This is also not the
> original resolution. (It was taken in 2048 x 1536 -- the posted image
> is 1024 by 768).

That's pretty noisy all right. Could you post the EXIF information as well?

BTW - I'm also seeing a lot of other noise in patterns that seem familiar.
Any chance you can put the original up somewhere?

> I'm a pretty lame rookie photographer and am just getting into the
> whole digital stuff. I always try to get the best pictures using the
> "manual settings" that the camera lets you set on your own, yet people
> tell me the "Auto" usually works best.

Well - maybe. For now. But not when you've got some experience under your
belt.

And, of course, shooting in Auto won't get you that experience.

> I don't know, I guess I'll learn as I go!

Yep. And the only way to learn is to shoot a lot and screw up a lot. Don't
worry about it.
Anonymous
January 3, 2005 7:46:32 PM

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

"VR" <vroric@gmail.com> wrote in message
news:1104746019.150738.104860@z14g2000cwz.googlegroups.com...
SNIP
> http://img.photobucket.com/albums/v487/vr044/IMG_0025.j...
> This is a shot of my dog I did a few days back. Notice the noise
> around the puppy's ear? (That's where it's very visible.)
SNIP

That is going to be prefectly eliminated by Neat Image, without loss
of significant resolution.

Bart
Anonymous
January 3, 2005 9:07:34 PM

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

Martin Brown <|||newspam|||@nezumi.demon.co.uk> writes:

> VR wrote:
>
>> Bob, what would I use for an image that I want to shoot indoors at
>> night with somewhat direct, yet soft lighting?
>>
>
> A classical SLR with a very fast lens and 1600 ASA film possibly push
> processed to 3200 ASA.

That kind of lighting works *much* better in digital than on film.
I've been fighting low tungsten lighting on film for 30 years before I
finally got my first DSLR, and it's like night and day.

> PS you can usually hide some of your noise by selectively blurring
> the blue channel. It is worrying that your half sized dog image
> still shows quite a bit of noise - could be your software has a poor
> choice of downsampling algorithm or the original was underexposed
> and taken in very poor light. Try using the camera in automatic mode
> for a while.

And doing a B&W reduction that omits or mostly omits the blue channel
can help a lot too.

Still, the blue channel in my digital originals is *much* less
compromised than the blue channel in scanned film.

> Averaging over 4 pixels (or alternatively median filtering) will
> disguise the noise but you will lose resolution too.

Which is why Noise Ninja, for example, can help a lot.
--
David Dyer-Bennet, <mailto:D d-b@dd-b.net>, <http://www.dd-b.net/dd-b/&gt;
RKBA: <http://noguns-nomoney.com/&gt; <http://www.dd-b.net/carry/&gt;
Pics: <http://dd-b.lighthunters.net/&gt; <http://www.dd-b.net/dd-b/SnapshotAlbum/&gt;
Dragaera/Steven Brust: <http://dragaera.info/&gt;
Anonymous
January 3, 2005 11:04:45 PM

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

VR wrote:
> Bob, what would I use for an image that I want to shoot indoors at
> night with somewhat direct, yet soft lighting?
>

It's hard to tell for sure.
If you use ISO 50 but you don't have much light, your camera will use a
longer exposure to capture enough light for a good picture. This will
cause fuzziness unless your camera is on a tripod and the subject is static.
If you bump the ISO to 400, the exposure may be short enough to
eliminate the effects of camera shake but the higher signal
amplification in your camera will produce noise.
Pick your poison. Camera shake or noise?
The ultimate answer, of course is MORE LIGHT, but that is not always
possible.
In subdued lighting, the eye is not used to seeing lots of detail. So
some noise may not be all that objectionable. Depends a lot on the mood
you want to create.
Some film photographers deliberately use very high speed film in order
to get a very grainy effect. That is their artistic license.
Just try it both ways. See which poison appeals to you most.
That is one of the beauties of Digital.
Bob Williams
January 5, 2005 8:31:55 PM

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

VR wrote:
>
> Eric, I'm using the "Superfine" quality setting.
>
> http://img.photobucket.com/albums/v487/vr044/IMG_0025.j...
> This is a shot of my dog I did a few days back. Notice the noise around
> the puppy's ear? (That's where it's very visible.)


Maybe you set the ISO higher than necessary or see if you can turn of
the in camera sharpening & see how ISO might be getting adjusted
depending on conditions & what mode you set it in. Sharpening
exaggerates noise. Then you can smooth or blur maybe parts of the image
& do the sharpening afterwards.
Anonymous
January 6, 2005 1:11:27 AM

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

In message <1104731644.612103.304930@f14g2000cwb.googlegroups.com>,
"VR" <vroric@gmail.com> wrote:

>Does lowering the resolution lower the
>noise level?

It makes the image look less noisy, but it is also more blurry, or less
detailed, if printed at the same size as the original resolution.

What is safe to say is that if your final target is a lower resolution
(like an 800*600 web picture), then you have to worry less about noise,
but even then, noise reduction before the size reduction will result in
a slightly better image.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
January 6, 2005 1:13:26 AM

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

In message <1104746019.150738.104860@z14g2000cwz.googlegroups.com>,
"VR" <vroric@gmail.com> wrote:

>No, no... I didn't mean "shoot at 2048 x 1536 and then downsample the
>image with software." I was saying "shoot at a lower resolution right
>away." But I suppose that's not gonna improve my images.

You're almost always better off just capturing the full-res image in the
camera, and doing all the surgery in software. The camera's routines
are usually geared for speed; not quality.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
January 6, 2005 1:24:01 AM

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

In message <m2is6et5tl.fsf@gw.dd-b.net>,
David Dyer-Bennet <dd-b@dd-b.net> wrote:

>That kind of lighting works *much* better in digital than on film.
>I've been fighting low tungsten lighting on film for 30 years before I
>finally got my first DSLR, and it's like night and day.

With most digital cameras, the red channel is the least sensitive,
because its filters cut out more light, so an over-abundance of red
light is actually beneficial. The native color balance of most CFAs is
in the cyan to green range, and warm light counter-balances them well
(optimally for grey/white subjects, of course).

If you look through all the scaling factors in dcraw.c ( "premul[]" )
for the various cameras, you will see that most RGB CFA cameras are
either most sensitive in the green channel, and weakest in red and blue,
or most sensitive in green and blue, and weakest in red.

--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
!