Am 07.06.2013 12:57, schrieb johannes hanika:
> my 2ct:
>
> - underexposure + digital exposure correction is terrible wrt noise
>
> - i think our highlight reconstruction (this is about hardware clipped
> pixels in the input) has some problems currently, if i find some time i
> want to fix this.
>
> j.

According to my understanding we have two separate issues.

1) pixels that are clipped in raw. If not all channels are clipped we 
can reconstruct the lightness information but not the pixel color. 
Reconstruction in LCh, as offered by the highlight reconstruction 
module, only works for isolated highlights where surrounding pixels have 
valid color information - does not work for the typical larger clipped 
areas in sky.

One idea could be a color reconstruction with a bilateral filter in Lab. 
We populate an <x,y,I> room with a-b-values from unclipped pixels and 
reconstruct clipped ones by interpolating with their (x,y,I) values.

2) pixels that are driven above L=100 in darktable, e.g. in the 
basecurve module. There is no convenient method ATM to bring them back 
into reasonable values. Shadows&Highlights would be a good candidate. 
But the current implementation clamps all pixel values to [0,100] and 
loses highlight detail. This behavior could be changed. We only need to 
make sure that legacy history stacks deliver the current output.

my 2 cents.

Ulrich



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