filmscanners_owner@halftone.co.uk <> wrote:
>> The question is: Is a better image produced from one method than the
>> other? Is it wrong to have a large file then scale down? Or is the
>> image slightly sharper, better resolved (or whatever the correct
>> terminology may be...), any thoughts? Ideas? Anyone produced any
>> tests?
>
> This a very interesting issue and I was just thinking about raising
> it to the list, as we are having an enriching discussion between
> photographers here. Some friends say that scanning must be done to
> the exact final size, because every resampling is destructive. As an
> example, one of them called for scanning a pure black, thick line
> drawn on a pure white background, and then resample/downsize via
> bicubic or whatever: the borders turn grey, which is a color not
> present in the original image. He concluded that downsizing blends
> colours and creates artifacts (but, since he's operating an Imacon
> Flextight maybe he doesn't really need to increase detail).
The question is whether the alising is an artifact of the resampling or if
it is due to some other factor in the scanning process. I have no knowledge
of the inner workings of the Imacon; but I believe (the engineers among use
will correct me if I am wrong) most other non-drum scanners do the raw scan
at their maximum optical resolution capabilities and then manipulate that
data via resampling to other resolutions in their scanner software.
If he is scanning with the Imacon in RGB a pure black line against a pure
white background, there are no other colors to be blended technically and
what is being experienced is a form of alising which could come from factors
other than resampling. For instance, the thick black line may not have been
all that sharp to begin with when examined under magnification and the
scanner captured the fuzzy edges of the line which in fact were there prior
to any sampling or resampling. Or the line when scanned is converted into a
bitmap image rather than a vector image so the scanned image line may not be
all that smooth to start with and may not be all that sharply delininated
from the white background as it appears ( it may actually have the jaggies)
which would then effect the resampling outputs appearance particularly for
that type of image; but a more pictoral image may not be effected
noticably.
> Other colleagues are scanning at maximum resolution -to capture all
> the detail the scanner can resolve- and downsizing later. Here, the
> point is to apply some techniques recently discussed on the list via
> wise sharpening filters between resizings.
It usually is not recommended to apply sharpening filters between
resamplings; but rather the application of said filters is usually left as
the last task before saving the file for archiving or before sending it to
the printer to output a hard copy.
>
> I have carried out several simple on-screen tests with my LS4000 and
> couldn't really tell a difference, but again this might be tested on
> large printed copies. Any thoughts from the real experts here?
>
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