The key, I believe is whether you want a screen resolution (what you were
viewing) versus printing. You need a heck of a lot more pixels to print it
in a quality that doesn't show the pixels.
In my experience, with both an Alps Dye-sub printer and the Epson 1270
printer, around 240dpi is required for a decent print. I've read of this as
the magic number, and my experience has proven it to be true.
Simple math for an 8 1/2 x 11 (what the sheets come in), says;
8.5*240 = 2040
11*240 = 2640
For a 13x19, which I print a lot,
13*240=3120
19*240=4560
So, for excellent 81/2x11 (or A4), the 2700 dpi scanners do a great job.
For 13x19, a 4000dpi scanner makes a big difference. The challenge for the
19inch dimension and a 2700 dpi scanner is 2700/19=142dpi, which is very
marginal for the biggest prints.
As for JPG, I don't believe it is a mathematical representation, but I could
be wrong. Regardless, it is lossy, so even the highest quality won't match a
TIF. I scan 35mm negs into TIF, at around 62MB per TIF. Even at 90%
quality (which is very high), JPG's are around 6MB still. Of course,
resizing smaller and less quality for the web makes them manageable, but not
what I would print from. Think about it, a 36 exposure roll, at 60Mb per
pic takes over 2GB.
My thoughts.
Tom
>
> > To print 8x10 well, you need a digital image at least 2000x1600 pixels
in
> > size, though some say 3000x4800 is necessary for best possible quality.
> > Naturally, any JPEG compression used on these images will eat into the
> > quality.
> >
>
> I haven't followed these threads at all. But I now have to scan some
slides.
> I was going to by a Nikon Coolscan for work, but this bloke at work showed
> me some stuff he scanned with a flatbed from slides. The resolution was
300
> dpi. He then kept zooming in and the results looked great until zoomed in
a
> lot (I forget the exact amount, but is was big). Only then did it start to
> show pixelation. What am I missing?
>
> Also, he said jpeg is a mathmatical representation of the image, not the
> image itself. And it is the same quality as the original. So with no
> compression selected, jpeg will be about 1/8 of a tiff file. Increase
> compression, and the trade off with image quality happens quick. Resave,
and
> it recomputes and quality drops.
>
> The scanner was a Microtek Scanmaker X6 ELM. He seemed very happy with it.
> All the results I saw were excellent, and he confirmed they were from 35mm
> film. The software could automatically determine if it was a negative or a
> slide.
>
> Foxy
>
>
>
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