When to upscale?

[Mahombi]

Under what circumstances would scaling up beyond 100% be used?

In this instance, I have a 6cm x 12cm transparency which I want to scan at optimum quality for maximum reproduction size.

[LSI_Ketelhohn]

Dear customer,

the scaling factor is used to calculate the correct image size for certain print resolutions.

For example you can preset 300dpi (the intended print resolution) and the enter the size of the image to be printed.
For example a 300dpi preset and scaling factor of 300% would result in a 900dpi (300dpi x 300%) scan.
Entering 900 with a scaling of 100 would result in a scan of the same size.

kind regards,
Arne Ketelhohn.

[Mahombi]

I understand your answer Arne, but it doesn't really tell me what I want to know.

Essentially, what I'm asking is, would scanning a transparency scaled at 200% provide better quality than the same one scaled at 100% (assuming both are scanned at the same resolution)? I remember reading somewhere that scaling up doesn't affect image quality like up-sampling does.

I'm thinking in terms of in the days of film, when if one wanted to print a 30"x40" sized print and only had an 8"x10" print to start from, it would be better to make a 4"x5" copy neg from it rather than a 35mm one. In other words, the enlargement ratio is less.

[LSI_Ketelhohn]

If you set the scaling to 200% it will use twice the resolution than a 100% scan.
The scaling only influences the resolution nothing more.
This does not do anything different than as if you would for example raise the resolution from 300dpi to 600dpi.


kind regards,
Arne Ketelhohn.

[Mahombi]

I've always been led to believe that more resolution means a higher quality image. Is that not so?

[LSI_Ketelhohn]

Basically you are right.

I only wanted to point out, that it makes no difference if you select e.g 600dpi and 200% scaling or directly select 1200dpi.
Both basically delivers the same image.

Higher resolution images of cause deliver more details.
But they are also more prone to noise.
In addition many scanners are capable of scanning at resolutions well above the maximum resolution of film (which is about 3000-3500dpi for most films).
This can result in images which show a "spotty" look at 100% view.
This is due to the fact that the scanner was capable of showing the film's emulsion.
Of cause SilverFast can reduce this effect through the GANE tool but you should be sure you need images that large.
Otherwise it would be sensible to chose a resolution which only shows image content.

The same goes for reflective scans.
Most prints do not offer resolutions above 600dpi (most are way below this value).
Scanning at higher resolutions does not make much sense here either (unless you need a very large image).


kind regards,
Arne Ketelhohn.