[photo-3d] Digital drawbacks

["Jim Harp" <matmail2@xxxxxxxxxxxxx>]

> No one thought these were digital prints.  I didn't think so, either, at
> first...
> One thing caught my eye - and instantly branded the prints as digital.  A
> picture of stadium chairs showed moiré patterns on the fabric of the chair
> back.  Further inspection of the images showed more interference patterns
> here and there, such as on a distant brick wall, I remember.
>
> This is an inherent drawback of digital: the necessarily repeating, regular
> pattern of sensors on the film plane (or output device) will form an
> interference pattern in an image that includes a pattern of similar
> regularity and spacing.
>
> As a fan of digital myself (I love music CDs for their convenience,
> robustness, signal to noise ratio, and dynamic range), I wonder if this
> problem shows up in digital audio?

You bring up a good point about the problems inherent in digitizing anything
- even though marketing types will always refer to digital media as
"perfect".  The interference patterns you describe are the result of not
having a high enough sampling rate.  With sufficient pixels the bricks and
fabric patterns would be accurately reproduced.  Similar to movies with
helicopters in them - because the film's frame rate isn't high enough we see
the helicopter blades slowly turning backwards.  In digital audio the same
thing happens, although the problems aren't as easy to quantify. The complex
high harmonics of a violin are rendered harsh square waves.  This is why
many classical music fans haven't gotten rid of their turntables.
Professional digital audio products get around this by using at least twice
the sampling rate of CDs and higher bit rates.  This gear is also way more
expensive than consumer products.  Note that the audio equipment being
marketed to consumers has been diminishing in quality for the past 10 years