filmic, a personal view


#21

Based on @davidvj’s post, the white rel exp - black rel exp = 14.68 - -10.72 = 25.40


(Gustavo Adolfo) #22

@andrayverysame it’s still in dev.

In my case, I installed it from source by following the procedures outlined by the “git version” section of Darktable’s install web page. (not sure if it also applies to Windows, I’m on Ubuntu).

If you’re going to do that, it’s important that you backup all your .xmp files as well as /home/USER/.config/darktable folder. it will be necessary in case you want to downgrade.


(ph. weyland) #23

Could you share the xmp please ?


#24

The problem is how to find a good mid-gray value.
I would do in this way
open the image with neutral setting


in the metada you could read that is underexposed about 2 stop, so we do the inverse (+2 stop )

Here is our mid gray (rawtherapee)

Simple brightness,contrast,saturation sliders and the highlights look a little flat


(Aurélien Pierre) #25

Dynamic range values are tabulated on dxomark.com. For example, here: https://www.dxomark.com/Cameras/Sony/A7R-III---Measurements#measuretabs-3

The XMP are always embedded in the JPEG files, however, as I work on the next version of the module, you might not be able to apply them, to here is a screnshot of the parameters for the guided filter:

Capture%20d%E2%80%99%C3%A9cran%20du%202018-11-26%2007-28-42

(notice that the “preserve the chrominance” option is not yet in master)

Your mid-gray is wherever you want it to be, since the lighting of the scene is not uniform, and that’s the whole point of filmic: remap it.


#26

Sorry but we disagree.
Because this is the Darktable category here’s my edit with .xml


20181020_0038.RAF.xmp (18.2 KB)
Brightness,contrast,saturation and one rgb curve so that mid gray is “correctly” mapped.

No noise amplification, natural looking colors, no posterization


(Aurélien Pierre) #27

The scene-referred mid grey is relative to a specific illumination. In a multi-illuminations scene, you have to choose the reference illumination as the one lightening your subject. Depending what you consider the subject in this picture, your illumination is not the same (reflected on direct light), thus your grey is not the same.

If you use filmic and target a grey that is already at 50 % L, then you do nothing (you remap 50 % -> 50 %), except maybe adding a bit of contrast with the curve.


#28

Or amplify the noise, for a well exposed shot there aren’t any pratical reason to use log gamma.

Log really shining when a photo is under exposed, but if the noise is amplified too much it could be due to a low dynamic range from the camera or that it was choosen an irrealistic mid gray


(Aurélien Pierre) #29

You have other algorithms to deal with the noise. It’s always a matter of trade-off. Every transfer function that raises the shadows will increase the noise (even a simple exposure lift), so this is not specific to the log.

What is log gamma ?


(David Vincent-Jones) #30

Must say that your results make a healthy start to the development process. I must admit that I cropped prior to any processing which in turn may have eliminated some extreme levels.
I am sure that you have a better ‘feel’ for this module than most of us; the logic, despite the manual, is somewhat alien to me at this time … and yes I did RTFM (printed it too).


(Gustavo Adolfo) #31

@davidvj But I think @age didn’t use filmic in his version, just the tools he mentioned…


(Aurélien Pierre) #32

Hi there,

darktable 2.6rc1 should bring a more stable framework to find the best settings in Filmic, with a much clearer curve to read and no more weird jumps between close parameters values. Merry Christmas !