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Old Oct 3, 2005, 9:35 PM   #1
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I recently purchased an OLY 800, for its size, manual controls, larger sensor, and all weather features. I do not need the 8m resolution to view photos on the computer. My question is: how does taking photos in lower resolutions really work? Are all the elements actually used? Is there a different compression being used? Is there any difference between the output of 8m camera when taking shots at say 5m then the output of a camera that has 5m maximum? I realize that more resolution basically means bigger files that can be printed out larger, but I do not print.

BTW, I am waiting for the Fuji F11 or E900 for indoor shots, although the Oly 800 is not nearly as bad as some people say!

Rube
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Old Oct 3, 2005, 9:41 PM   #2
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Rube39 wrote:
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Are all the elements actually used?
Your question is quite large :lol:, but for this part only, I think yes, because the camera need the whole area of the CCD (the whole frame) , and probably make an interpolation to get smaller definition. The interpolation algorithm should be different for each manufacturer.
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Old Oct 3, 2005, 9:55 PM   #3
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Rube39 wrote:
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I recently purchased an OLY 800, for its size, manual controls, larger sensor, and all weather features. I do not need the 8m resolution to view photos on the computer. My question is: how does taking photos in lower resolutions really work?
Like KCan already said, it's going to vary by manufacturer. Most are going to use the entire CCD and then downsize the photos using one algorithm or another.

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Is there a different compression being used?
Perhaps. Again, this will vary by camera manufacturer. See what you think of the photos using it this way. I'd personally use a camera in it's highest resolution mode. Then, downsize the images myself later if smaller viewing sizes were needed.

You never know when you'll get a shot you may want printed at larger sizes (or someone else may want to print at larger sizes). Memory cards are relatively inexpensive anymore.

Also, who knows what kind of resolution your monitor will support in the future. I remember when monitors with320x200 resolution were common, able to display a whopping 16 different colors at the same time.

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Is there any difference between the output of 8m camera when taking shots at say 5m then the output of a camera that has 5m maximum?
Sure. The a 5 Megapixel Model may provide better images, with better dynamic range, colorand detail compared to your 8 Megapixel model. Or, the opposite may be the case. You can't judge image quality by the number of megapixels a camera has (although it does seem to sell a lot of cameras). ;-)

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Old Oct 3, 2005, 10:09 PM   #4
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Very good answers, thank you!
Yes, I will take a number of trail shots (of the same thing) at different resolutions and look at the results.

And I realize that different manufactorers get different results. I am still wondering however, if there would be a difference between, for example, the photos taken with a Canon S60 (5m) and a Canon S70 (7m) if the resolution was restricted to 5m in both, because they are supposed to be the same camera except for the bumped up resolution in the S70.

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Old Oct 3, 2005, 10:23 PM   #5
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Rube39 wrote:
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And I realize that different manufactorers get different results. I am still wondering however, if there would be a difference between, for example, the photos taken with a Canon S60 (5m) and a Canon S70 (7m) if the resolution was restricted to 5m in both, because they are supposed to be the same camera except for the bumped up resolution in the S70.
You'd need to try it.

Also, it may depend on the condtions.

As a general rule, all else being equal, a camera with more megapixels in the same sensor size will have more noise as ISO speeds are increased, degrading image quality more compared to the lower resolution sensor. Advances are being made in sensor design though. So, this is not always the case.

In the Canon models you asked about, I think that the Sony 7MP Sensor used in the S70 offers some improvements over the Sony 5MP Sensor used in the S60.

But, I doubt you'd see much difference in them at the same resolution settings. In some cases, you do see more detail from a higher resolution model after downsizing, compared to a lower resolution sensor.

I can remember comparing some 100% crops fromimages taken by the Canon G5 and G6 a while back. The G5 uses a Sony 5MP sensor, and the G6 uses a Sony 7MP sensor.

For the most part, the G6 images looked a bit better (especially from a Chromatic Aberrations and noiseperspective). But, to my surprise, in some of the shadow areas, the G5 beat it based on the samples I looked at (taken of the same subjects, in the same conditions, at almost exactly the same time, with both models).

I think it probably had to do withthe mage processing algorithms (which could be causing loss of detail from noise reduction algorithms in the supporting chipset or firmware) in shadow areas where more noise can be more prevalent (it's usually worse in underexposed areas).

You really have to look at these things on a case by case basis, since everything is not going to be the same between two different models from the same manufacturer, especially if they are using a different sensor.


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Old Oct 4, 2005, 1:52 PM   #6
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These are your resolution/quality choices:
3264 x 2448 (SHQ)
3264 x 2448 (HQ)
2560 x 1920 (SQ1)
2272 x 1704 (SQ1)
2048 x 1536 (SQ1)
1600 x 1200 (SQ2)
1280 x 960 (SQ2)
1024 x 768 (SQ2)
640 x 480 (SQ2)

You can see that your highest quality is available only at full resolution. Quality is determined only by the JPG compression quality. You have to drop two steps in compression quality to get to the next lowest resolution.

From my reading on the subject it appears that all consumer cameras downsize by interpolation of the full sized image. There are some scientific instruments that allow you to selectively disable some of the sensors in multiples of 4. So the next step down from 8Mp would be 2Mp. I doubt your camera does that even at 2Mp though. The way the sensors are interrelated in the Bayer interpolation used by most camera CCDs would probably make it difficult to just disable 3/8 of the sensors to get a 5Mp image.

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