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Old Apr 21, 2004, 1:29 PM   #1
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Default Kodak 5mp vs 6 mp when enlarging--please help!

I have been using a Sony 3mp for 2 years, but when I crop an image and want to print a 4x6 or 5x7 (and especially 8x10) I loose alot of quality. So I just bought a Kodak 5mp DX4530. I've taken pictures and cropped quite a bit to experiment for the last 2 days, and it is quite a bit better.

However, now I see that in May there will be a 6mp Kodak camera out, and I can still return the 5 and exchange it, but it's $250 more! It's also an SLR, and I don't want that much camera, I just need a point and shoot.

HERE'S MY QUESTION: I know I saw quite a bit of difference in the resolution when cropping and enlarging from 3mp to 5mp, but will I see enough difference in 5mp to 6mp to justify spending so much more? Please help, I've got to decide!
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Old Apr 21, 2004, 4:04 PM   #2
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It takes 4 times the resolution to double the image size (since resolution is composed of width x height). So, the difference between 5 and 6 Megapixels is really very negligible.

Likewise, when cropping, you can't crop as much as you think. If you crop an image so that it appears to be half the size, you only have 1/4 the original resolution.

Are you interpolating your images after cropping? Your problem could be pixelation.

I sometimes crop a 5 Megapixel Image down to around 2 Megapixels, then interpolate back up again before printing. I use a free software package (irfanview) to accomplish this, using the Lanczos setting (Lanczos is one of the available interpolation algorithms).

Of course, interpolating does not add detail (but it does allow larger prints without pixelation).

The "real detail" captured (going from a 5 Megapixel to a 6 Megapixe CCD) is likely to be negligible. In fact, the 5 megapixel CCD may even be better in lower light at higher ISO speeds, since not as many pixels are being packed into the same size sensor. As a general rule, the smaller the photosite for each pixel (as in the newer, higher resolution sensors), the higher the noise levels.
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Old Apr 21, 2004, 4:08 PM   #3
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Default To Jim C

Unfortunately, I'm such a newbie to all this digital talk, I don't know what interpolating is! But it does sound quite helpful to me.

Thank you for your information, it makes me feel much better about hanging onto the 5mp camera.
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Old Apr 21, 2004, 4:18 PM   #4
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Interpolating an image basically adds pixels to it, based on the values of adjacent pixels.

This will not add detail that was not captured, but will allow larger print sizes without pixelation.

One good free package is irfanview. Download it from http://www.irfanview.com

Make sure to download the free plug-in's, too.

Then, use the Image, Resize/Resample Menu to interpolate the image. I use the Lanzos Filter option personally.

When printing an 8x10" print, I'll usually crop the image first, then interpolate up to 300 pixels per inch (3000 x 2400 for an 8" x 10" print).

This is probably an "overkill" (most printers won't need this much resolution). However, the 8x10's are usually very stunning this way from my printer, even if I start with an image that is around 2 megapixels to begin with.
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