[filmscanners] VueScan 7.4.2 - an appreciation, and questions about file sizing

["Julian Vrieslander" <julianv@mindspring.com>]

The rate of development for VueScan over the last few weeks has been
astonishing:

Histograms, graphically selectable focus point, live display updates,
monitor color spaces, separate panes for controls and displays, and much
more.

For a lot of VS users, I suspect that the top items on their requested
feature wish lists have already been added.  Thanks once more, Ed, for
producing a great product, with terrific support for your customers.  And
I'd like to know what vitamins you are taking...

By and large, I think Ed has done a good job at expanding the
functionality of VS, while keeping the user interface elements organized
and transparent.  If there is a fault to VS as a product, it is in the
documentation (User's Guide).  The descriptions are often too brief,
unclear or confusing.  This material really begs to be fleshed out.  In
some places, diagrams or screenshots would be very helpful.  An improved
User's Guide might reduce the amount of time that Ed spends responding to
frequently repeated questions.

There is one area that really needs better description.  I am not sure I
understand it myself.  This is the new group of controls in the File tab
that control Image units, Image size, and Image dpi.  I understand the
basic concepts of resolution and image scaling.  But the documentation
does not explain the various options in the Image size popup menu.  Here
is my guess at what is going on:

In the following descriptions I assume that "image" refers to the data
written to the tif or jpg output files, and that "scan" refers to the
cropped area of the scanned media.

"Image size = Scan size"  Image resolution is set to the dpi selected in
"Device |Scan resolution."  Image dimensions are set to the crop
dimensions: "Crop | X size" and "Crop | Y size".

"Image size = Fixed dpi"  Image resolution is set to the value entered in
"Files | Image dpi".  Image dimensions are computed by multiplying the
crop dimensions by a factor F = (scan dpi / image dpi).

"Image size = Manual"  Image dimensions are computed by multiplying the
crop dimensions by the largest factor G which will keep image size within
the limits set by the user in "Files | Image width" and "Files | Image
height".  Image resolution is computed from (scan dpi / G).

"Image size = a standard size"  Image dimensions are computed by
multiplying the crop dimensions by the largest factor H which will keep
image size within the limits set by the selected standard size.  Image
resolution is computed from (scan dpi / H).

If the above descriptions are correct, none of these settings will cause
any resampling (no pixels are changed, added or deleted).  They only
affect the image size and resolution tags in the output files.  I hope
that Ed or someone else will correct me, if my understanding is wrong.

--
Julian Vrieslander <mailto:julianv@mindspring.com>

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