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Old Mar 27, 2005, 12:06 PM   #1
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is there an optimal resolution to shoot with when you only want to print regular sized photos?

also, does 8 megapixels do anything other than let you shoot at higher resolutions? does it make digital zoom better for instance?
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Old Mar 27, 2005, 9:20 PM   #2
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First of all, if regular size means your typical 4"X6" print then 1200X1800 is the resolution needed to make 300DPI prints of photo quality. This is just a little more than 2MP. Obviously if you want bigger you need more resolution, an 8"x10" print would be 2400X3000 at the same 300DPI, this is just over 6MP. 300DPI is not a magic number but it is a resolution level which produces prints that will be real photo quality. For larger prints resolution as low as 150DPI may be acceptable since we view these prints from a greater distance normally.



8MP cameras allow for much larger prints, as for digital zoom, some companies such as HP and Fuji, actually only allow digital zoom at lower resolution levels, or report the size of the resulting crop. An 8MP camera could use a 4x digital zoom and still produce a very good 2MP image, suitable for 4"x6" photo album prints or web based photos. I am not familiar with the performance of the 8MP cameras currently available as to digital zoom, my opinion is that more total resolution will allow greater practical use of digital zoom but it should still be viewed only as a last result since a good photo editing program can be used to crop the larger files after the fact.



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Old Mar 28, 2005, 12:48 AM   #3
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Another important fact is the ability to reduce interpolation artifacts by using a higher resolution. Most cameras use a color grid and interpolate the colors. If you can affort to reduce the size by 50% you increase the picture quality that way that you almost eliminate the interpolation artifacts.

Resizing is a non trivial process (!) and a decent resizing process increase picture quality on the price for resolution. Your 8MP gets down to a almost perfect 2MP, which printed with 300DPIresult in an excellent 4x6 print.
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Old Mar 28, 2005, 4:47 PM   #4
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ok I see, so a resized 8mp picture will look better than a resized 3.2mp picture? but won't stuff in the picture look smaller? or just cleaner?
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Old Mar 28, 2005, 5:57 PM   #5
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Since an 8MP image starts out with so many more pixels, when it is sampled down to a smaller file size it will have more detail then most files of that size. There is also that possibility to crop images, something that you cannot do much of in a 2-3MP image. The actual content of the image is dependent on the angle of view of the lens so an 8MP file sized down to 2MP will contain the same view as a 2MP file taken with a lens of equal angle of view, this has nothing to do with MP.



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Old Mar 28, 2005, 6:31 PM   #6
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ok, thanks
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Old Mar 29, 2005, 8:15 AM   #7
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Monza76 wrote:
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... An 8MP camera could use a 4x digital zoom and still produce a very good 2MP image, suitable for 4"x6" photo album prints or web based photos. ...
Nope. The "x" factor in a digital zoom is a linear measurement which means you have to use its square to determine the pixel count reduction, 16 for a 4x digital zoom.

The other way to look at it is to consider the linear pixel count of the camera. A typical 8Mp camera produces a 3264 x 2448 pixel image. Dividing the long side by 4 yields 816 pixels. At 200 ppi, that means the long side of the print would be 4 inches.
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Old Mar 29, 2005, 4:37 PM   #8
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Quote:
Nope. The "x" factor in a digital zoom is a linear measurement which means you have to use its square to determine the pixel count reduction, 16 for a 4x digital zoom.

Oops:?

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