heya,
On Sun, Dec 15, 2013 at 8:20 PM, <junkyardspar...@yepmail.net> wrote:
> I've recently been playing with the HDR capabilities of darktable, with my
> basis of information being the blog post here:
> http://www.darktable.org/2012/10/process-hdr-images-using-darktable/
>
> The results are much nicer, and much less of an unnatural "effect", than I
> was ever able to achieve in the past with other methods (enblend/enfuse,
> etc.). Now that I don't hate HDR pictures as much,
hehe, i know what you mean..
> I'm curious about a few things:
>
> When using the "create HDR" button in lighttable view to merge a few
> bracketed raw files, what (if any) processing of the raw files becomes part
> of the produced .dng file?
first, a disclaimer: this merging process is really dumb. it was very fast
to implement, that's why we have it. you will probably run into situations
where it's not appropriate to use it.
it just merges the plain raw pixels, the only thing done to them is
subtraction of black level, scaling to white according to their
exposure/aperture/iso settings, and then the values are written to dng.
doing it that way doesn't require to extract a `camera response curve' as
needed for jpg. in fact, it doesn't even demosaic. raw linear sensor data
is awesome.
i think some metadata is copied over, too.
> And should I be manually disabling any auto-applied modules when loading
> that file, as implied in the above blog post? The image seems to benefit
> from the auto-applied base curve; should I be getting that tonal boost
> somewhere else in the pipeline when doing HDR processing?
>
not sure what the hdr file defaults were at the time of writing of the blog
post. i think there was some auto-applied tone mapping, which sometimes
looks like the terrible pictures you described above.
>
> Also, is using "global tonemap" + "local contrast" actually very much
> different from using the "tone mapping" module?
similar. the difference is that `tone mapping' uses some global brightness
adjustments and is thus harder to control in my opinion. it uses a
different algorithm for the bilateral filter than `local contrast'.
> I don't doubt that it is, but exactly how so isn't obvious to me from my
> experiments so far. I'm just curious, and further experimenting with both
> methods may answer my question, but if there's an easy answer, it might
> make me feel less stupid faster. ;)
>
> As always, thanks for the great software.
>
> P.S. - I also noticed that there are no tooltips for the controls on the
> "local contrast" and "tone mapping" modules, in case that's been overlooked.
>
oops, indeed. will have to be fixed after the release (string freeze).
cheers,
jo
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