I plan on copying all the family slides and negatives using a Dimage
Scan Elite 5400.
I will save the scans to DVD’s. I plan to create slide shows for use
on the TV
and the computer. What is the best resolution to use when scanning
these slides and negatives?
Do it in steps is the best solution.
The first step is to scan the image at the native resolution of the
scanner. This almost certainly (unless you happen to have a computer
display designed for air traffic control!) well above the resolution
that your final output will need, but it provides you with a couple of
significant advantages.
The first is a "future proof" original scan - so in the future when you
change your TV to a flash new flat panel device, or your computer to a
display that is only available at the moment to ATC operators, you won't
have to scan all of those images again.
The second, and almost as important, though you probably don't
appreciate how much at the moment, is that you end result will be far
superior to scanning at the resolution that your output needs. This is
all to do with how you downsample the image to the output resolution and
the effect that the various downsampling algorithms have on image
quality. Implementing downsampling in the scanner itself probably means
using "nearest neighbour" resampling - which is technical speak for
throwing away all of the extra samples. At best you might get linear
interpolation, which means taking some account, on a linear weighting,
of all of the samples close to the output of each sample. However there
are many alternatives each offering a particular advantage, whether lack
of moiré from aliasing or sharper edges or whatever.
Of course, if you follow the advice then the first advantage offers
benefits to the second - you can try the different options out on your
original equipment.
You can find the end resolution for your computer system just by looking
at the display properties. For TV it really depends on what your
equipment is. In the US and its territories, as well as Japan, the TV
resolution is 640 x 486 pixels. In Europe and most of its territories
the resolution is 768 x 575 pixels. But that isn't necessarily the best
resolution to display on your particular screen. If you have a new
plasma or LCD TV then you should look at the user manual to determine
the native resolution of that unit and use that for your images -
especially if you are sending them to the screen directly from the
computer. If you are recording to DVD as a video stream then the
intrinsic horizontal resolution will be 720 pixels, irrespective of the
video standard - with 486 or 576 vertical pixels (these aren't square
pixels on the video system so the image will look squashed horizontally
on the computer!). Then, do you want your scans to display in a couple
of years time when HDTV has taken the world by storm? And which HDTV
standard will that be? The interlaced 1080line standard proposed for
the US and its territories or the progressive 720line standard proposed
by the European Broadcasting Union for its?
I am sure that you think you have asked a simple question but the answer
really depends on the equipment you have and it will not be the best
answer at all in a couple of years time, irrespective of the equipment
you have now.
So you will get a lot of replies, some right some not so right - because
there really isn't a right answer. That is why the best answer for your
requirement is to scan at the capabilities of the equipment you have -
and the Minolta is almost as good as the film itself! Then create your
application slideshow to fit whatever standard you happen to need at any
time in the future.
You can be fairly confident of being cold in your grave before TV ever
gets close to the capabilities of the scanner you are proposing to use,
so the limitations of your scanner should not enter into your
considerations.
