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In lugnet.space, Todd Lehman writes:
> In lugnet.space, David Laswell writes:
> > [...] Basically, digital zoom doesn't do anything that you can't
> > accomplish by enlarging the image with MS Paint.
>
> I don't think that's quite correct. If your CCD or CMOS chip has greater
> than 8 bits of depth on each spectral band (most do), then an on-camera
> digital zoom should contain more information than a post-processed
> zoom.
>
> For example, suppose you have a 10-bit CCD (common), 10x digital zoom,
> and 5x optical zoom. Now if you take a 24-bit color JPEG photo at 10x
> (digital zoom), download it from the camera, load it into Photoshop, convert
> it to a 16-bit image, and resize the image to 50% (half size), that _should_
> contain more detail than if you had just taken the photo at 5x (optical zoom).
> If they look identical, then the camera has a really poor digital zoom.
I think you are confusing color depth with image area resolution. If the
CCD chip has an area of X-by-Y pixels and you are at maximum optical zoom,
then any form of digital zoom requires interpolating between adjacent real
pixels. The color depth of those real pixels does not help the
interpolation process for the spatial data that lies between those real pixels.
For example, if you're interpolating between the two numbers 11.111111
and 33.333333 you've got a specifc linear gradient between them (22.222222).
Adding extra digits of precision (11.11111111 and 33.33333333) does not
change the gross value of the gradient, it only gives greater precision to
the gradient (22.22222222).
Whether that interpolation takes place in the camera or on the PC doesn't
help get more spatial detail between the real pixels in the zoomed area. In
fact, if you do it on the camera you have to throw away all the real pixels
outside the area you digitally zoom to, thus losing the opportunity to ever
do so in the future.
Brian
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Message has 2 Replies:
 | | Re: taking good photos
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| (...) I didn't think that sounded right, but I couldn't figure out why. This sounds an awful lot like how LCD laptop screens work, where they look fine if you set the screen size according to the actual physical pixelation of the screen, but if you (...) (21 years ago, 22-May-03, to lugnet.space, lugnet.publish.photography)
| | | Re: taking good photos
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| (...) I don't think I am. :-) I'm not saying that the end result of a 2x-downsampled 10x digital zoom will look any better in 24-bit color than a native 5x optical zoom would look in 24-bit color. It won't. What I'm saying is that a 2x-downsampled (...) (21 years ago, 2-Jun-03, to lugnet.space, lugnet.publish.photography)
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Message is in Reply To:
| | Re: taking good photos
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| (...) I don't think that's quite correct. If your CCD or CMOS chip has greater than 8 bits of depth on each spectral band (most do), then an on-camera digital zoom should contain more information than a post-processed zoom. For example, suppose you (...) (21 years ago, 21-May-03, to lugnet.space, lugnet.publish.photography)
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