I just did some tests with some RAW TIFFs I created from my scanner
using vuescan and imported them to darktable.
I attach a sample file for you. This has room for improvements but
doesn't look so bad.
http://up.picr.de/20188260fw.jpg
No target, just use the invert module to get the orange mask correctly,
create a base curve, and doing white balance by using the R-G-B-Sliders
instead of color temperatur or the picker.
regards
Bernhard
Bernhard schrieb am 17.11.2014 um 20:02:
I use this workflow
https://web.archive.org/web/20080421211129/http://privat.albicker.org/foto-tutorials/foto-tut-neg-en.html
-Bernhard-
Steven Fosdick schrieb am 17.11.2014 um 19:18:
I have been using Darktable for some now for digital pictures but I
recently borrowed a slide/negative scanner and used it to scan some
old negatives I had. While searching I also discovered a couple of
rolls of undeveloped film from years back which I got developed.
Looking at the colours from the negatives they seemed a little odd
but when I got the recently discovered films back from developing
complete with CD scans from the developer these have turned out to
have very different colours from those I get if I scan the same
negatives myself.
Here an example:
http://s16.postimg.org/tchwpmfwh/img22highres.jpg
This is the scan that came back from the people developing the film.
http://s16.postimg.org/l5pwy1ptt/img22raw.jpg
This is what I get if I scan the film myself.
I also have an example where water is a very obvious purple. As I
have already scanned quite a few images and had to return the
scanner, at least for the time being, I am wondering if can work out
a colour correction to be applied to the images from the scanner I
borrowed. Moving the sliders in the white balance or colour balance
modules to search for useful settings does not seem to work very
well. Taking samples from patches of what should be the same colour
on each of the scan from the developers and the scan from the scanner
I borrowed, working out the ratio for each colour and then setting
that as the gain in the colour balance module works but only for that
patch, i.e. that patch then becomes the same colour in the corrected
version from my borrowed scanner and the scan from the developers but
the rest of the picture retains noticeably incorrectly coloured.
So this suggests to me that the film or some aspect of the scanner
does not respond linearly and the extent of the non-linearity is
different for each colour. This is presumably what the other sliders
in the colour balance module are intended to correct but again moving
them around whilst visually checking is not very productive.
I know there is a step in adding a new camera to produce a colour
matrix which can be done given an IT8 target where there are various
shades of exactly known colours but I can't see a way to do that in
this case. IT8 targets do not seem to be available on negative film
and the films I have been scanning are old so even buying an IT8
target, finding a film camera and a similar roll of new film,
photographing the target, developing the film and then running the
new camera colour matrix tool on the resulting scan would not
necessarily yield the right results as the film formulation may have
changed in the intervening years (20 or more, in some cases).
Could a similar process work for multiple patches where for each
patch a sample (r,g,b) is taken from the desired colour and another
(r,g,b) for the uncorrected colour picking, for example, both strong
colours and neutral areas, shadows and highlights? Does anyone know
of a tool that would be able to process these to work out the
parameters for colour balance (or as a colour matrix to add as if it
was a new camera)?
If not what other approach would you use?
------------------------------------------------------------------------------
Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
from Actuate! Instantly Supercharge Your Business Reports and Dashboards
with Interactivity, Sharing, Native Excel Exports, App Integration & more
Get technology previously reserved for billion-dollar corporations, FREE
http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk
_______________________________________________
Darktable-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/darktable-users
------------------------------------------------------------------------------
Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
from Actuate! Instantly Supercharge Your Business Reports and Dashboards
with Interactivity, Sharing, Native Excel Exports, App Integration & more
Get technology previously reserved for billion-dollar corporations, FREE
http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk
_______________________________________________
Darktable-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/darktable-users
------------------------------------------------------------------------------
Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
from Actuate! Instantly Supercharge Your Business Reports and Dashboards
with Interactivity, Sharing, Native Excel Exports, App Integration & more
Get technology previously reserved for billion-dollar corporations, FREE
http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk
_______________________________________________
Darktable-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/darktable-users
