I see two main things in this thread:
- colors are radically different on the bridge (and only on the bridge) between the OOC JPEG and RAW rendering engines, regardless which one (e.g. LR, DT, RT all put the bridge blue unless some extra color mapping is applied)
- up close, there are significant artifacts on the bridge trusses when rendering from RAW (with DT and RT, LR seems to fare better here) when compared with the OOC JPEG.
As I understand it (after reading up on samples clipping), this might be due to out-of-gamut but also possible channel-specific overexposure on the bridge. Indeed, messing with highlights reconstruction does improve the detail on those trusses on the bridge significantly, but it never quite matches the results from Lightroom or the OOC JPEG.
Now, I understand much better the issue of gamut: it’s not something I considered for this at first, and it totally makes sense that the camera would shift pixels one way while rendering engines would shift them another way, especially if there was film emulation enabled on the camera (or, as @houz suggested, “instagram filters” :). I understand this and it makes sense: this is special changes made to the color mapping and we can’t expect rendering engines to reproduce that exactly, especially out of the box. So my immediate surprise at the difference of rendering at the color level is passed now and, well, I accept that the bridge may actually be blue (still an open question, btw - I haven’t found someone who could answer this definitely).
What concerns me more at this point is the difference in detail. There is precious data from the sensor, and it seems we (free software RAW rendering tools) are losing some of it, while our proprietary equivalent fare better. Is there something we’re missing in the algorithms to render this? Why can LR render those trusses without clipping?
Again, to compare, the OOC JPEG:
Darktable, linear Rec709
:
Lightroom, out of the box:
And, for completeness, @heckflosse’s try with RawTherapee:
Now of course the colors are completely different in the four images: I understand better why, that makes sense. What I can’t wrap my head around is why the details are so different on the bridge truss. In the OOC JPEG and the LR rendering, I feel I could keep going and zoom another crop and still keep detail. In DT and RT, I feel I’ve already lost and we see a lot of grain on the trusses. I have tried to mess around with highlight reconstruction, but I couldn’t quite get the same result: I mostly end up with a washed out, blurry picture. Nothing as sharp as the original.
Now, I am very grateful for all the answers. The level of technical and artistic knowledge here is impressive and humbling, and I can only thank you again and again for all your efforts. I did feel it would be useful to reframe the question, since we have pretty much cleared the field of the color (blue/magenta) problem, I think.
So if people want to pursue the conversation here little further, I’d be very curious to hear what people think of the detail problem next.
PS: is this something that should be in “play raw” next time I have a trick question like that?