On Wed, May 24, 2017 at 3:49 PM, Аl Воgnеr <[email protected]> wrote: > I read > http://www.darktable.org/2012/12/profiling-sensor-and-photon-noise/ and > want to create noise profile images with a Pentax KP. > >> take one shot per iso. > > 1 step ISO, 1/2 steps or 1/3 steps? Smaller steps will produce a lot of > photos, the Pentax KP supports 819200 ISO. Basically, all the ISO that can be set in camera. So certainly 1/3. And if with 1/2, different values can be set, maybe those too.
If the profile for a given iso does not exist, it will be linearly interpolated from the nearest samples on the each side. >> it has to be out-of-focus and have a widespread histogram, i.e. be >> over- and underexposed at the same time (see example image below). if >> you want to be thorough, take 2-3 to verify the numbers. > > So it should not be a normal sharp nightshot, but something out of > focus, eg a street lamp in the night? I'd try to search for raws used for noiseprofile generation for some other camera and examining them. But yes, something like bright lamp illuminating half of the shot, and total darkness on the other half, with gradient change from one to the other one. >> this image looks very green, because the `raw linear' style has been >> applied to it (find it in darktable/tools/noise). this makes sure we >> get linear camera raw rgb with no basecurves, no whitebalance, etc in >> the way. it is essential that you apply this style. > > So I have to change the camera to RGB? Are sRGB *and* RGB photos wanted? That is talking about the dt processing. Unless the manufacturer is *really* *really* dumb the in-camera color space selection only matters for the JPEG's, and the embedded thumbnails. > Al Roman. > ____________________________________________________________________________ > darktable user mailing list > to unsubscribe send a mail to [email protected] > ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to [email protected]
