Posted by M.I.5� on 01/08/07 12:59

"Joshua Zyber" <joshzyber@comcast.net> wrote in message
news:Ruadnen9Ta731wPYnZ2dnUVZ_uWlnZ2d@comcast.com...
> "M.I.5�" <no.one@no.where.NO_SPAM.co.uk> wrote in message
> news:459e111d$1_1@glkas0286.greenlnk.net...
>> If you really want to be padantic, The resolution of film, analogue video
>> and digital video are impossible to compare in any quanitifiable way
>> because they manifest themselves in inherently different ways and have to
>> be measured and quantified in very different ways.
>>
>> Video sourced material on a DVD is much sharper than film originated
>> material. It cannot really be measured but it is a fact (and you have
>> agreed that that is the case). Film material projected onto a screen is
>> sharper than video originated material. Again, it can't be measured, but
>> it is true.
>
> The original resolution of film can't be measured because it's a
> photochemical process, not an electronic one. However, once transferred to
> DVD, both film and video have the exact same resolution: 720x480 pixels
> (or 720x576 for PAL).

Yes, but so what?

> All DVDs have the same measurable resolution. Don't confuse resolution
> with sharpness; they are not the same thing. As far as not being able to
> compare the sharpness of two different sources, you could say the same
> thing about any two productions photographed differently than one another,
> regardless of format. Movie X can be sharper than Movie Y simply because
> that's the way they were shot. Has nothing to do with film or video.
>

But it is an inherent feature of the digitalisation process that when you
move from the analogue domain to the digital domain, each pixel of the
digital domain gets its infomation from an correspondingly larger area of
the analogue source. Although the physical number of pixels is fixed, the
circle of confusion (to misuse an analogue term) is larger than one pixel
(and is totally dependant mainly on the source material, but also on how
good the conversion process is), thus diluting the real resolution.

Obviously a digital video source will retain its full resolution, but
although it would appear to be dependant on the very analogue lens system,
the MTF of the lens is more often than not, not the limiting factor (unless
you have a really cheap and nasty lens).

>>> If you're having problems reading movie credits on DVDs, it's probably
>>> your TV and/or DVD player causing the problem. Can I assume you still
>>> use an interlaced set?
>>
>> I only have problems reading the very small credits (as does everyone
>> else).
>>
>> As the DVD is interlaced, what possible difference can it make?
>
> Oh good lord. The DVD may be interlaced, but the fields can be
> reconstructed into whole video frames on a progressive scan screen. That's
> the whole point of progressive scan. Please read this:
>
> http://www.hometheaterhifi.com/volume_7_4/dvd-benchmark-part-5-progressive-10-2000.html

The arguments in that cite are valid only when the video system is
progressive scan from start to finish. If the source material is
interlaced, then converting it to progressive, still means that the odd
numbered lines occur in a time frame one fiftieth of second earlier than the
even numbered lines. Displaying interlaced source material on an LCD TV
doesn't look any different than if the DVD player is set to convert to
progressive. On a CRT TV there are considerable advantages from the flicker
reduction, but this is countered because twice the bandwidth is required for
the video content. This is one of the reasons interlaced video replaced
progressive (or sequential as it was called when it was abandoned in 1936).

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