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Old Oct 24, 2009, 4:05 PM   #1
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Default Shooting at Lower MPs ??

I have never come across a discussion on whether shooting at lower megapixels reduces noise/artifacts etc.

I am considering purchasing a Panasonic compact, which are accepted as having noise/smearing and wondered if by selecting lower megapixels (say lowering from 12mp to 8mp) I could get better details and improved IQ.

Has anyone come across any info on this?

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Old Oct 24, 2009, 4:32 PM   #2
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I would also like an answer to this question.

Tiny sensors compensate for the generated noise by using powerful noise reduction algorythems. I would assume (and we all know what that means) that since the senor compression is the same, that the level of noise would be the same, given the fact that it's the same level of packing in the recievers.

Hopefully someone with more knowledge can clear this up...

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Old Oct 24, 2009, 4:43 PM   #3
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I have never come across a discussion on whether shooting at lower megapixels reduces noise/artifacts etc.

I am considering purchasing a Panasonic compact, which are accepted as having noise/smearing and wondered if by selecting lower megapixels (say lowering from 12mp to 8mp) I could get better details and improved IQ.
Reducing the resolution of an image does reduce image noise, but it also reduces detail and sharpess, resulting in lower IQ.

The vast majority of those photoreceptors are going to record real image data. Only a very few will produce data that does not accuratly represent the scene. By reducing the resolution, data from mulitple photoreceptors are averaged together to produce a less accurate image. Yes, the effect of individual errant pixels will be averaged out, but so will the many more pixels that accuratly represent the scene.
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Old Oct 24, 2009, 7:18 PM   #4
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TCav has it right - averaging does reduce noise a the same time it reduces resolution. Since that can be done at least as well in post processing, there really is no reason to do it in camera. More processing power is available in your computer, and a choice of algorithms.

To your specifics, the noise is reduced by something like the square root of the pixel count. That means cutting from 12 to 8Mp would reduce the noise by something like 22%. To get really noticable effect you would have to reduce resolution to something like 3Mp for a factor of about two in noise.
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Old Oct 24, 2009, 9:10 PM   #5
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TCav has it right - averaging does reduce noise a the same time it reduces resolution. Since that can be done at least as well in post processing, there really is no reason to do it in camera. More processing power is available in your computer, and a choice of algorithms.

To your specifics, the noise is reduced by something like the square root of the pixel count. That means cutting from 12 to 8Mp would reduce the noise by something like 22%. To get really noticable effect you would have to reduce resolution to something like 3Mp for a factor of about two in noise.
I'm puzzled. My understanding is that noise on these little digicams is a result of random electricity escaping from the individual sensors. The closer the packing of the sensors, the more likely that an adjoining sensor will pick up on this stray electricity. Since the solution of manufacturers is to use heavy noise removal algorhthyms, what difference does it make (one way or the other) to use a larger or smaller crop? Still the same sensor?

And since there's no way to turn the noise removal off, sure, why not take the larger image - But either way you have already eliminated detail.

I'm not going to argue with anyone on this issue because I lack the expertise. But my solution has always been to buy a P&S with a small megapixel count, and a camera that doesn't use noise removal software.

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Old Oct 24, 2009, 10:02 PM   #6
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Depends on each camera's engine.

With my P&S, I get much better result shooting at highest resolution and resampling on my computer. If I shoot at lower MP, it takes the picture at maximum resolution and resize it internally(not resample) and it looks like ass.
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Old Oct 24, 2009, 10:14 PM   #7
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I'm puzzled. My understanding is that noise on these little digicams is a result of random electricity escaping from the individual sensors. The closer the packing of the sensors, the more likely that an adjoining sensor will pick up on this stray electricity. Since the solution of manufacturers is to use heavy noise removal algorhthyms, what difference does it make (one way or the other) to use a larger or smaller crop? Still the same sensor?
Yes, but if the algorithm uses the surrounding 24 pixels to calculate a value that's most likely to be true for an errant pixel, then the smaller the portion of the entire image those 24 pixels constitures, even if the calculated value is way off, it will have less of an impact on the quality of the entire image.

Also, often, those noise reduction algorithms have trouble distinguishing noise from detail.

In other words, in general, the more pixels, the better.
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Old Oct 25, 2009, 12:47 PM   #8
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Much thanks guys for increasing my understanding...

Dave
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