On Tue, 01 Apr 2003 02:18:19 -0500, John Dyson <fred@dyson.net> wrote:


>Boyle wrote:


>> Is there a simple way to measure how many lines of resolution a DVcam

>> can produce on TV?  Thanks


>For an approximate method, I use an SMPTE resolution chart, and

>point my camera at it.  Then, I use a TV monitor that can max

>out the specified resolution of DV (at least 540TVL.)  You

>really need a higher resolution than that, because most monitors

>start rolling off before the limiting resolution.


>A really good DV camera will provide 480TVL - 540TVL.  Actually,

>it needs to roll-off before the limit, otherwise you get unpleasant

>aliasing effects.  (The 540TVL corresponds directly to 720 Pixels,

>where the 540 == 720 * 3 / 4.  The 3/4 (or 4/3) is the aspect

>ratio.  For 16:9, similar formulas appply.


>Any PRO 3CCD camera will likely be able to max-out the resolution

>of DV.  Other limitations would cause differing picture quality.


>The DV encoding scheme actually does throw away detail that isn't

>directly measured by resolution charts.   It is SOMETIMES better

>to throw away SOME of the normal 'spatial' resolution so as to

>avoid losing other kinds of detail that isn't directly specifable

>in TVL.  Also, if you try to push too much detail through a DV

>encoder (inside the camera), it is likely to produce mosquitos

>or excess stairstepping in the vertical dimension.




Nice answer!