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Old Jun 10, 2005, 6:14 AM   #1
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How much cropping can I get away with?

I use a Panasonic FZ 20 and leave it on the max resolution when taking pictures.

I need help on cropping. If I have a full picture and want to crop out a smaller subject then print it, how small of a portion of the picture can I use without causing me to loose too much quality. I print mostly the 4x6 but would like a 8x10 once in a while.
Is there something I should be watching other than the size ratio? Please help me I am a new at the photo shop stuff.
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Old Jun 10, 2005, 6:30 PM   #2
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If you crop a photo to make it look like you used twice as much optical zoom, you end up with 1/4 the original resolution.

So, you really can't crop as much as you think if you're going to be printing very large.

You can interpolate it to help reduce pixelation (which adds pixels, based on the values of adjacent pixels), but this doesn't increase the detail captured by the sensor -- only the number of pixels in the image. Bicubic is a popular algorithm to use for interpolation.

How well an image will interpolate will depend on the type of subject.
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Old Jun 10, 2005, 7:06 PM   #3
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So your saying that if I crop out 1/2 of the picture taken at 2500 res,then I would not have a quality 8x10?:?


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Old Jun 10, 2005, 7:48 PM   #4
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It will depend on the subject.

If you go too much below around 150 pixels per inch (which is around a 2 Megapixel Image for an 8x10" print), you'll start getting too much degradation with most printer drivers (some interpolate back up for you, some don't).

You won't have 2 Megapixels left after cropping a 5 Megapixel image to make it look like you used twice as much optical zoom.

But, you can interpolate the image again to increase it's resolution (which does not increase the detail captured, since it's only adding pixels based on the values of adjacent pixels). The quality of the interpolation varies depending on how much you are trying to enlarge it, and what tool you are using.

As to the quality of a print after interpolation, it depends on how much detail was in the image to begin with representing your subject. What may appear to be a lot of detail in an image, may not be after enlarging it (since the human eye/brain tends to fill in gaps when it recognizes portions of an image).

Lin Evans has a good explanation of this here:

http://www.stevesforums.com/forums/v...mp;forum_id=23


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