| Burned highlights is bad, because it means that information is
| lost. There are methods for reconstructing that information
| back. Rawtherapee, which I just installed to test this, has a method
| called "Color propagation". From what I understand, it uses surounding
| pixels in the burned area to reconstruct the burned components.
|
| For example, this is a sample picture I tested with.
[...]
|
| CR2: https://www.dropbox.com/s/fkzymeor14ypmfx/IMG_0450.CR2
This is a RAW file with clipped data in one or more channels. Clipped
data cannot be recovered (the data is gone) but in some situations it
can be invented via interpolation from other available data.
Data that is intact in the RAW file but that is then blown in
postprocessing is different. The original data is there in the RAW and
is simply being curved or processed away. That means that it can be
processed *back* and fully recovered, at least in theory; the challenge
is to do it easily without huge amounts of manual manipulation and also
to do it in a way that visually natural and appealing.
(For example, going to a linear base curve will recover most or all
of those blown highlights in a single action but generally makes your
picture look terrible. Going to a linear base curve with this CR2 shows
that, well, the data is gone, it's hard-clipped.)
I am specifically interested in recovering highlights that are intact
in the RAW but blown in post-processing. Interpolating RAW-clipped data
is a hard enough problem that I am happy for the darktable developers to
say 'well, there's nothing we can really do to help except possibly make
the area go white instead of having wacky colour casts'[*].
(The current git tip darktable actually gives the clipped area a colour
cast by default but then curves it away to nearly pure white. As usual,
you can see this clearly by looking at the pre-base-curve version
through the history stack.)
- cks
[*: I would be happy to see a highlights reconstruction option for 'if
any channel is clipped, set the pixel to white'. I might even turn
it on all the time.
]
------------------------------------------------------------------------------
How ServiceNow helps IT people transform IT departments:
1. A cloud service to automate IT design, transition and operations
2. Dashboards that offer high-level views of enterprise services
3. A single system of record for all IT processes
http://p.sf.net/sfu/servicenow-d2d-j
_______________________________________________
Darktable-users mailing list
Darktable-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/darktable-users
