Today I finally got some free time to try shooting some calibration
photos with my new camera, and I did two things. Well, three, kind of.
1.First I tried to use the darktable-chart tool to build a full color
correction profile, but this didn't work and I couldn't figure out why,
so...
2. I used the base curve tool with some test chart images and a photo of
a white wall + grid spotted light + some black posterboard and actually
came away with a pretty good base curve that got me a lot closer to what
I saw in the back of my camera (and with the manufacturer's RAW
processor if I tried that) than any of the built-in profiles had done
(and rightly so, it looks a lot different from any of them).
3. I finally realized my mistake from step 1, which is that I'd tried
just using imagick to convert a reference jpeg to pfm, when I needed to
import it to DT so I could export it in Lab colorspace. Once that was
done I managed to generate a complete style from a color checker shot.
The generated style with its settings for the color LUT module has
/drastically/ improved the color rendering for RAW files from this
camera. What I'm curious about is that the generated style applies a
very similar curve to the base curve that I generated in step 2, but it
applies it as a tone curve and turns the base curve off.
Does anyone know why it does this? I thought you generally wanted to
apply a base curve that more or less matched the one the manufacturer
uses, as a starting point, but when we generate these styles we're not
using one at all. I noticed that if I tried turning off the tone curve
and applying the base curve that I generated it seems to make the color
LUT do some weird things, so I'm guessing that has something to do with it?
____________________________________________________________________________
darktable user mailing list
to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
