In the bottom-left pane is the subtract tool, subtracting the value 0.001953125, which is 128 converted to rawproc’s internal 0.0-1.0 floating point. Now, here’s the rendition with the libraw supplied black value of 143:
I downloaded black-GX9 and opened it in rawproc, same deal as for the G90. EXIF black level is 128 for all three channels, libraw black level is 144. Here’s a screenshot of the exif black level:
No, it shouldn’t. Weirdly enough, RT (dcraw) extracts the exif black levels first. The value of 15 in camconst.json is needed as an additive correction to that.
Okay, I guess if you’re going to use dcraw code you’ve gotta find a way to live with the subtraction it’s going to do for you, hard-coded. However, IMHO camconst.json could use better semantics to express the difference between a delta value and a replacement value…
Perhaps for some compressed cases (floating point predictor?), I doubt the uncompressed one requires the DNG SDK… It’s been a while, the answer is in the LibRaw source code of course…
Hmm, so it seems the situation has at least somewhat improved. That’s good to know, most of the references I found were not looking promising initially, and that particular issue discussion had strong WONTFIX undertones to it.
As a side note, it’s kind of disappointing that the state of compression options in DNG without doing something non-standardized has kind of stagnated. Unless you are Bayer-mosaiced you’re basically limited to 8-bit lossy JPEG. I’m curious what feeding the lj92 predictors into a more modern entropy coder (such as the underlying ones used by zstd) would result in performance-wise.
I’ve got one of the original poor man’s cameras the canonet ql17 which was the poor man’s Leica, using Olympus om analogue lenses on a Panasonic gives a camera with similar functionality and I guess the original Olympus OM1 is now the poor man’s Olympus OM1
Hey @ggbutcher yes, the camconst comment gets tweaked over time but its still bloaty and unclear. Could you point to or quote the part in question, or even better open a PR with a fix?