[sane-devel] Parameter Default Values
kare.sars at kolumbus.fi
Wed Apr 11 10:10:40 UTC 2007
On Wednesday 11 April 2007, Olaf Meeuwissen wrote:
> I should have added that the epkowa backend also contains an ever
> growing list of model dependent matrices in epson_scan_hard. Each
> entry may specify up to four matrices, one for reflective originals
> (paper, etc), colour negative, B/W negatives and colour dia positives.
> IIRC, the B/W negative matrices are always the identity matrix.
If I understand this correctly the values are "calibrated" for the different
models and scan sources (and should be sane :).
> You originally wrote:
> > The problem I have is that the default values for the color correction
> > parameters ('cct-1' -> 'cct-9') give me a yellow page (original is white)
> > when I write back the original value to one of the parameters. If I don't
> > touch any of the cct parameters I get a white page.
> I assume you have checked that when you "write back the original
> value" that that's indeed what gets set, right?
> There might be endian issues and SANE_FIX/SANE_UNFIX confusion.
The problem I had earlier was probably that the "write back the original
value" was a little off :(.
As you can see in my last post I now get a good image :). I could not
reproduce the "yellow" image, but wondered where the "magic" numbers came
> > BTW today the image is quite fine even tho the paramete values are
> > quite 'magic' :)
> Your debugging output quite nicely matches, within floating point
> precision, the entries for the RX500/RX510.
> > I also noticed that changing the film type when scanning with the
> > transparency unit changes these (cct) values.
> See my first comment above as to why.
> None of your setValue() calls seem to try to set one of the cct option
In the my code, the sane options are 'connected' to GUI objects that write the
values to the backend when the user changes the values. When I sent the first
mail, the GUI Object probably modified the value and wrote it back to the
backend modified. Since then I have modified the change quantization step
size of the GUI objects.
The important question for me was "Might there be a need to modify default
values to get a good image". If I read your answer correctly the answer would
be "No" at lest for these parameters.
PS. My project can be found at SourceForge:
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