Moire in Canon A590

Today I tried to take a picture of the strings of a grand piano,
from the back end, and got a significant moire pattern in the area
where the bass strings lie above the treble strings, but are strung
in different directions. This criss-cross area looked pretty bad.

Is there anything I can do to reduce or eliminate this effect? Any
camera setting that I could select?

Would a better camera do better in this situation, or is it just
physics? Does the A590 not have any low-pass filter to reduce this
aliasing problem?

Peabody

On Wed, 04 Nov 2009 19:09:52 -0600, Peabody <>
wrote:

>Today I tried to take a picture of the strings of a grand piano,
>from the back end, and got a significant moire pattern in the area
>where the bass strings lie above the treble strings, but are strung
>in different directions. This criss-cross area looked pretty bad.
>
>Is there anything I can do to reduce or eliminate this effect? Any
>camera setting that I could select?
>
>Would a better camera do better in this situation, or is it just
>physics? Does the A590 not have any low-pass filter to reduce this
>aliasing problem?

Turn down the in-camera sharpening to the lowest level. Might help to turn
down contrast to lowest level too. You will also avoid that by simply
changing the angle of your sensor to the angle of the moire'-causing
subject. You can rotate later in post-processing (use Lanczos-8 resampling
algorithm if available for rotations and resizing).

Do those sharpening and contrast phases in post processing. I never let any
camera handle those to any degree if it allows for it.

Info Man

Peabody <> wrote:
> Today I tried to take a picture of the strings of a grand piano,
> from the back end, and got a significant moire pattern in the area
> where the bass strings lie above the treble strings, but are strung
> in different directions. This criss-cross area looked pretty bad.

> Is there anything I can do to reduce or eliminate this effect? Any
> camera setting that I could select?

> Would a better camera do better in this situation, or is it just
> physics? Does the A590 not have any low-pass filter to reduce this
> aliasing problem?

You will always be able to get moire effects when viewing images at
less than the meximum size. The camera's anti-aliasing filter only
applies to its maximum resolution.

Do you still see this effect on the maximum full size image?

--
Chris Malcolm

Chris Malcolm

Chris Malcolm says...

> You will always be able to get moire effects when
> viewing images at less than the meximum size. The
> camera's anti-aliasing filter only applies to its
> maximum resolution.

> Do you still see this effect on the maximum full size
> image?

Well, using the full 8MP, and viewing the pic on my biggest
monitor, the moire is almost completely removed. Actually,
the problem may have been more in the display medium than in
the picture itself. The smaller the display, the more
the moire shows up. Review on the camera itself is
particularly bad.

I hope that means it won't show up in prints.

Thanks for your help.

Peabody

"Peabody" <> wrote in message
news:mTsIm.3249$...
[]
> Well, using the full 8MP, and viewing the pic on my biggest
> monitor, the moire is almost completely removed. Actually,
> the problem may have been more in the display medium than in
> the picture itself. The smaller the display, the more
> the moire shows up. Review on the camera itself is
> particularly bad.
>
> I hope that means it won't show up in prints.
>
> Thanks for your help.

Peabody,

When displaying at less than full image resolution you really need
software which resamples the image correctly rather than using some
nearest neighbour pixel selection (exaggerating moiré). Make sure that
resampling (even upscaling) is properly carried out when you print.

Cheers,
David

David J Taylor

"bugbear" <bugbear@trim_papermule.co.uk_trim> wrote in message
news: o.uk...
[]
> The A590 doesn't have a contrast adjust. Indeed, I'm not aware of a
> camera
> that does, or what it would (usefully) do.
>
> Could you help out?
>
> BugBear

Just two examples:

Nikon D5000 - compare Vivid with Natural:
http://www.dpreview.com/reviews/nikond5000/page18.asp

Nikon D700 compare Vivid with Neutral:
http://www.dpreview.com/reviews/NikonD700/page20.asp

I think that other non-DSLR cameras I've had provide similar options under
a variety of names.

Cheers,
David

David J Taylor

Alfred Molon wrote:
> In article <wBpIm.349$>, Peabody says...
>> Today I tried to take a picture of the strings of a grand piano,
>> from the back end, and got a significant moire pattern in the area
>> where the bass strings lie above the treble strings, but are strung
>> in different directions. This criss-cross area looked pretty bad.
>>
>> Is there anything I can do to reduce or eliminate this effect? Any
>> camera setting that I could select?
>>
>> Would a better camera do better in this situation, or is it just
>> physics? Does the A590 not have any low-pass filter to reduce this
>> aliasing problem?
>
> Canon uses too weak antialiasing filters in their cameras, to maximise
> the perceived resolution in the images. Other manufacturers use stronger
> AA filters to avoid this problem.

You have that backwards. Canons have *strong* antialiasing filters, &
tend to benefit from a bit of sharpening when processing from RAW.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Bob Larter

"bugbear" <bugbear@trim_papermule.co.uk_trim> wrote in message
news: o.uk...
[]
> The A590 does indeed have those, but I've never used them.
>
> I assumed (wrongly) you meant something more
> like auto-adjust levels, or contrast-stretch
> as found in DeskTop packages.
>
>
> BugBear

I didn't "mean" anything, BugBear, I was just answering your question
about cameras with a contrast adjust facility. Some of the Nikon range do
have the ability for in-camera post-processing as well, but I've never
used it, so I'm unfamiliar with that's on offer. See:

http://www.kenrockwell.com/nikon/d50...us-retouch.htm

If that's correct, it doesn't include level adjustment.

Cheers,
David

David J Taylor

bugbear says...

>> Turn down the in-camera sharpening to the lowest level.
>> Might help to turn down contrast to lowest level too.

> The A590 doesn't have a contrast adjust. Indeed, I'm not
> aware of a camera that does, or what it would (usefully)
> do.

Well, it has a contrast setting for taking the picture, but
not one for adjusting contrast after the fact.

So it lets you adjust contrast, sharpness and saturation. I
assume these are just settings for jpeg conversion, and
don't affect how the exposure itself is actually made.

Peabody

On Thu, 05 Nov 2009 09:17:56 +0000, bugbear
<bugbear@trim_papermule.co.uk_trim> wrote:

>Info Man wrote:
>> On Wed, 04 Nov 2009 19:09:52 -0600, Peabody <>
>> wrote:
>>
>>> Today I tried to take a picture of the strings of a grand piano,
>>>from the back end, and got a significant moire pattern in the area
>>> where the bass strings lie above the treble strings, but are strung
>>> in different directions. This criss-cross area looked pretty bad.
>>>
>>> Is there anything I can do to reduce or eliminate this effect? Any
>>> camera setting that I could select?
>>>
>>> Would a better camera do better in this situation, or is it just
>>> physics? Does the A590 not have any low-pass filter to reduce this
>>> aliasing problem?
>>
>> Turn down the in-camera sharpening to the lowest level. Might help to turn
>> down contrast to lowest level too.
>
>The A590 doesn't have a contrast adjust. Indeed, I'm not aware of a camera
>that does, or what it would (usefully) do.
>
>Could you help out?
>
> BugBear

I'm not personally familiar with the A590, but if it has the typical
Powershot "Custom Colors" setting, you can find it there. Turn down
sharpening, contrast, and the red channel to -2. That is the most accurate
sensor to JPG rendition I have found in the Powershot series, that which
matches the RAW data from that line of cameras. I use a different model of
Powershot with this "custom colors" feature and never take it off of those
aforementioned settings.

If your Powershot does not have that "custom colors" adjustment feature, I
guess it amounts to buying savvy. All the P&S cameras that I buy have both,
sharpening and contrast adjustment.

High contrast on the resulting JPG files in many consumer level cameras is
set inordinately high. The Nikon cameras being the absolute worst in this
regard. This is due to marketing where people expect an eye-popping image
right from the camera no matter the lighting conditions. I don't buy a P&S
camera unless it is renowned for its low contrast or has an option to turn
it as low as possible. The low-contrast cameras take full advantage of the
sensor's dynamic range to where there is rarely any need to obtain any RAW
data from the sensor. Sony cameras in the past used to be well known for
this lower contrast output (which I admired for their decision from a pure
photographer's standpoint), which sadly sharply cut into their sales due to
the vast inexperience of the snapshooting masses. The full dynamic range of
the sensor is reflected in those cameras' JPG output which innately have
low-contrast JPG output, or where it can be turned down.

Info Man