Linus said:
Thanks for your replies.
It seems I need some more in-deep knowledge about scannig tecnologies
All in all, with RAW I meant something equivalent to what RAW format is for
digital cameras.
So, something which is still a near representation of what the CCD "sees" .
I know that RAW files from digital cameras receive some low-level processing
before being output in the shape of RAW files. In other words, I am after a
file format whose aquisition parameters can still be manipulated.
Linus
P.S: I am from Italy so I understand that "catch 22" is a way of saying
(probably related with baseball, or cricket maybe), but I don't get its
meaning
Here is the description of saving raw file from Vuescan:
http://www.hamrick.com/vuescan/html/vuesc1.htm#topic0
Using Raw Scan Files
One of the most powerful features of VueScan is that you can save
the raw scan data in a file (using "Output|Raw file") when scanning.
These raw scan files can then be reprocessed later without needing to
re-scan the actual media again. You shouldn't ever need to scan the
same physical image twice.
The raw scan files are raw data straight from the CCD in the scanner,
without any sort of color processing or modification. None of the
options in the Filter or Color tabs affect the raw scan files in any
way (except that when "Output|Raw output with" is set to "Save",
the raw file has had rotation, mirroring, infrared cleaning and grain
reduction applied).
You only need to save raw scan files if you foresee a need to reprocess
the image in a later session. In any case, VueScan always keeps the
raw data from the most recent scan in memory, so you can always
reprocess it without needing to rescan the image. The only time you'll
need to rescan the image is if you want to change the cropping,
scan at a higher resolution, or if you want to manually change the
exposure or focus.
http://www.hamrick.com/vuescan/html/vuesc22.htm#topic21
Raw file (Professional Edition only)
This enables writing raw data from the scanner to a TIFF file.
The raw files are the result of the first of two steps VueScan performs:
"scanning". The second step is "processing". These steps are described in
the topic "How VueScan Works" in this User's Guide. By providing a
mechanism to cleanly separate these two steps, VueScan provides great
flexibility and options not available in most scanner software.
You can perform the "processing" step later by setting "Input|Source" to
"File". This lets you rescan images with different settings, without needing
to physically rescan the media.
When the raw file is written depends on the setting of "Output|Raw output with".
Raw files are always stored as TIFF files and can therefore be examined in
image viewing and editing programs. Note, however that the resolution of
raw files (as specified in "Output|Raw file type") may be greater than some
programs can read.
Little processing is done on raw files so they are a close representation of
exactly what the scanner has produced. Raw files will not be filtered nor
will color settings be applied. As a result, raw scans may look "wrong".
Raw files are good for archiving as they contain as much data as the
scanner was able to produce without any operations that modify the
scanner data.
The image gamma value is 1.0 when there are two bytes (16-bits) per
sample, and 2.2 when there is one byte (8-bits) per sample. Raw files
saved with gamma 1.0 will look dark, but this is normal.
The one exception to this is if "Output|Raw output with" is set to
"Save" - in this case, the infrared cleaning and grain reduction is also
done before saving the raw scan files.
Catch 22:
http://en.wikipedia.org/wiki/Catch-22