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01-16-2009, 08:32 PM   #1
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what is the difference bwt exporting to 8-bit or 16-bit tiffs?

what is the difference bwt exporting to 8-bit or 16-bit tiffs?

is there a better way to export using aperture to saved to an external hard drive?

01-16-2009, 09:29 PM   #2
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I don't have the program so I can't speak to that issue. I assume Aperture can export in both levels?

I may stand corrected but the way I understand this is as follows:

What you get with 16 bit vs 8 is a better gradient and higher dynamic range. In short the extra 8 bits gives you 256 values between each of the 256 values in any fixed value within the image. For example, when you take a DNG or PEF file and convert to TIFF a given pixel value has adjustment properties from 0-256 and with the extra 8 bits the gradient between each value is also 256. So you get smoother transitions (as colour shades transition from one area to another) and greater dynamic range. This may not show up in a web Jpeg but can make a huge difference in a printed enlargement.
01-22-2009, 05:17 AM   #3
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8-bit color (which is really 8 bits per channel, so R + G + B = 24 bits) gives you:

2^(3 * 8) = 16 777 216 colors

16-bit color means:

2^(3 * 16) = 2.81474977 ◊ 10^14 colors

That's a hell of a lot more. Still meaningless quality-wise if you save from an 8-bit source, but the K20D for instance captures RAW at 12 bits so to retain the full amount of color captured by the sensor you should save as 16 bits if you intend to process the picture further at a later date -- there will be a lot more "headroom" for further calculations.

With 8 bits you can encode 256 different values -- 16 bits means 65536. That is a very real difference when applying different digital filters and edits, which would otherwise introduce all sorts of quantization errors that gradually decrease image quality. Truncating to 8 bits is not a big deal when you're DONE with the picture though, because 16 million colors is enough for any print.
01-22-2009, 01:51 PM   #4
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I guess by looking at the above responses, 8 bits aint the right answer then.

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