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Old Feb 25, 2003, 8:57 PM   #1
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Default Clarification on Resolution between 2MP and 3MP

I would be grateful if someone could clear my doubt on the resolution. Take for instance two cameras of 2 megapixel and 3 megapixel from the same manufacturer. The 3 megapixel camera can be used to take a 2 megapixel picture. Now, will that picture be more clear (with more details) compared to the picture taken by the 2 megapixel camera. Or, the 3 MP picture is only meant to take a bigger print out. If there is difference in clarity, that means if we use a 5 MP or 6 MP camera and take a 2 MP picture, it will be much more clear compared to the one taken with the 2 MP camera. Those who have used different cameras may be able to give their expert views based on their experience. Thanks.
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Old Feb 26, 2003, 12:21 AM   #2
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Though I am relatively new to digital cameras and have yet to purchase one, 2 megapixels means 2 megapixels regardless the camera. In other words, the pictures will be the same since the same number of pixels is being used. 3mp merely gives you the ability to take a larger picture of something. Think of it like this, if you have 2 17 inch computer monitors and both are set to 1024 by 768 pixels, regardless if one can be set to 1600 by 1200 pixels and the other can only be set to 1024 by 768, the image displayed by both is the same. Granted some 2 megapixel cameras have better and clearer images than others, but that has to do with the quality of the sensor, lense and other factors, not being 2mp.
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Old Feb 26, 2003, 3:51 AM   #3
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There have been many previous posts on this topic. There are many other things which affect quality other than Mpix. The difference between 2 & 3 for a 6 X4 print will be small, the 2Mpix with a better lens, ccd sensor and something else, might be better. The something else is the amount of JPEG compression the manufacturer puts on. From cam manuals you can work out the file size from the number of pics they say you get on a card.

Let's say for example a 2 Mpix cam does 10 'fine' on a 16Mb card and a 3 Mpix does 20. You may start with higher resolution but trade off more artefacts once first compressed in the cam.

However, often you need to 'crop' pictures which means throwing away some pixels and magnifying to get the right size print. The 3Mpix cam could allow more latitude here. The real benefits should come by comparing say 2 to 4 or 5 Mpix. for say 10 x 8 prints and bigger. Also my Fuji will use it's 3Mpix as a 1Mpix cam with more sensitivity - and that can be V. useful sometimes.

Something few mention here, is it's no good having buckets of Mpix, low sensitivity and shooting handheld with zoom at slowish shutter speeds . Resolution and your cash becomes meaningless when you introduce even small amounts of blur due to shake.

Tripods are cheap and sometimes worth the effort. So a 2 Mpix cam with a f1.8 lens set up carefully and on a tripod or monopole, could give excellent pictures.
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Old Feb 26, 2003, 7:03 AM   #4
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Both voxmagna and ardvark50 are right. I'd like to emphasize that are no two cameras which are identical in every regard except the number of pixels.

If two such cameras did exist, there should be slightly (22.47%) more noise from in a native 2Mp image that in one downsized from 3Mp. That should occur because the pixels are "averaged" when downsizing.
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Old Feb 26, 2003, 11:05 AM   #5
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This question got me thinking.

How many cameras can actually trade less resolution (using the 3MP CCD to poduce a 2MP image) for less noise/higher quality? I know that I've seen talk about it before this post. I just wondered how common this feature it.
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Old Feb 26, 2003, 11:11 AM   #6
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All of the cameras that I have come in contact with have the capability to take lower resolution photos.
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Old Feb 26, 2003, 2:28 PM   #7
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Quote:
Originally Posted by eric s
How many cameras can actually trade less resolution (using the 3MP CCD to poduce a 2MP image) for less noise/higher quality? I know that I've seen talk about it before this post. I just wondered how common this feature it.
Even if the camera cannot shoot at a lower resolution (I think they all can), you can get the same noise reduction effect downsizing using a photo editor. Not at all sure which (camera or editor)will do a better job, though I supsect it will depend on the camera. Does it "average" the RAW data, then convert to RGB? Does it first produce a JPEG, then downsize? What algorithm does it use to downsize? Probably subtle difference, but could be real.

A few cameras do it explicitly by allowing high ISO only at low resolution.
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Old Feb 26, 2003, 5:06 PM   #8
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Quote:
Originally Posted by eric s

How many cameras can actually trade less resolution (using the 3MP CCD to poduce a 2MP image) for less noise/higher quality? I know that I've seen talk about it before this post. I just wondered how common this feature it.

I guess Fuji 601 is using this approach, by limiting resolution to 1M when you shoot at ISO 800 or 1600. With my canon S30, I could choose all the sizes (from 640X480 to 2048X1536) at highest ISO setting, 800. But the noise level is much higher if I chose a larger image size at this ISO setting.
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