[filmscanners] Re: 3 year wait

["Arthur Entlich" <artistic-1@shaw.ca>]

Laurie Solomon wrote:


>
>>"4K" simply means 4000 (and 96) pixels across the 36mm film chip.
>>Actually, 2889.9ppi.
>>
>


The problem above is the direction of the film being measured.

A film recorder refers to the longer dimension as 4K, so the 4096 pixels
across, represents the approximate 1 and 7/16th inch wide frame, (4096
pixels divided by 1.4375" equals 2849 ppi or so)

On the other hand, most film scanners scan the narrower width of the
film frame, so a 4000 ppi scanner needs to have a apparent sensor
density of about 3750 elements across the film frame in the short direction.


>>I'd say that 11-12MP of true pixel info IS pretty
>>much what (Ektachrome,
>>at least) film can resolve.
>>
> [What is a MP and is that a standard abbreviation?]
>
>


MP is Mega-pixel, as usually used in digital camera sensors. One MP is
1024K pixels (in an array).  So a one megapixel array would be about
1200 x 800 pixels.  However, the reason the reference is "true pixel" is
because other than the new Foveon chip, digital cameras use a CCD or MOS
array which can only record one color (RGor B) per pixel location, and
therefore an array is used (called a Bayer Pattern) which uses
interpolation to take a matrix of 25% R and B and 50% G filtered pixels
to make up the color information, and therefore the accuracy is
lessened, and interference patterns (moiré) develops with some color
combinations.


>>T-Max 100 has a resolution rating of around 200 line pair/mm, that's over
>>10k samples per inch, and would be a file of APPROXIMATELY FOR EXAMPLE SAKE
>>(since you are being anal about arithmetic ;-) ~10k x ~15k or ~150M pixels
>>
>
>


I'll leave someone else to explain this part, but the main point is that
you cannot measure to a single line because there needs to be a contrast
developed, meaning a series of lines, such as black line, white line or
blank space, black line, etc, to measure. That is why the term is line
pairs, since a minimum of two lines (or the space between them) is
required to read the result.

Art


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