Q-Factor

[L F Brown]

I'm trying to try out the demo version of SilverFast AI on my Epson V500. I'm having numerous problems, some of which have been resolved and others not so much, but I'm wondering about the "Q-Factor" window on the Frame tab. The only thing I've found mentioning it in the literature I've pulled up - including the manual I downloaded today - is that 1.5 is the recommended figure????? What does it do? How high does it go? What if I use a figure other that 1.5? How does it figure in to DPI or does it?

Does anyone have any info on this or a link to the necessary information?

Thanks

[LSI_Luebker]

Dear Customer,
normaly you should not need to play around wiht the Q-Factor.
Here is a good explanation from our FAQ:
Q:
The SilverFast user interface has an entry field for Q-factor. What does the Q-factor actually do?

A:
In SilverFast you have the possiblility to determine the scan resolution by setting the Quality Factor (Q-Factor). This Q-Factor indicates the relation between line screen resolution (lpi) and scan reslolution (ppi resp. dpi).
A Q-Factor of 1.5 means that the scan resolution is 1.5 times larger than the line screen resolution.

How to calculate the maximum scan resolution with no information loss.?
desired output sreen x quality factor x scaling factor = scan resolution

Example
scanning a photo that is destined to be printed at a print pattern of 175lpi, and the photo is scanned 1:1 size (not enlarged or downscaled) this is your calculation:

175lpi x 1.5 x scaling factor (1:1 = output scaling 100% = 1) = ? 175lpi x 1.5 x 1 = 262,5dpi

SilverFast runds it off to 262dpi

[L F Brown]

Thanks you for your explanation and reference to the FAQ page. I'm still confused, however, about the difference between lpi and dpi. How does lpi relate to film scanning? What is lpi , as opposed to dpi, to begin with. Why wouldn't they pretty much be the same number?

Since the Q-Factor input window exists and is accessible by the the user under what conditions would a person want to alter that figure? Also, just for clarification, I noticed that when the Q-Factor is increased the dpi increases. However, if I increase the dpi the Q-Factor does not change. There also doesn't seem to be a "reset" in the event some numbers are erroneously entered - other than shutting down SilverFast and re-opening.

Thanks once again,

L F Brown

[LSI_Luebker]

Dear Customer,

the Q-Factor is needed in the professional prepress area and for the general purpose it should be set to 1.5.
Here are some further informattions aboth LPI : http://www.silverfast.com/show/scanningconcepts/en.html

best regards,

Thomas Lübker,
LaserSoft Imaging AG