Hey Joachim,
first of all it is important to clarify if you understand how the so-called “pixelpipe” works in darktable?
If not, I recommend reading this part of the darktable documentation.
The most important paragraph there is this one:
“The order of the pixelpipe is represented graphically by the order in which modules are presented in the user interface – the pixelpipe starts with a RAW image at the bottom of the module list, and applies the processing modules one by one, piling up layer upon layer of processing from the bottom up, until it reaches the top of the list, where it outputs the fully processed image.”
In this “processing chain” the results of hierarchically lower lying modules serve as a basis for the processing for higher lying modules.
This processing order is already predefined based on the function of the modules and each module is placed in the most appropriate position for the respective module.
However, there are situations where it sometimes makes sense to change the order of the modules in order to achieve a certain result.
In the first example in the video, I first used the contrast eualizer module to reduce the coarse local contrasts caused by the countless branches. I wanted to calm down the texture of this area so that the viewer’s eye is not too distracted.
In the second step, I wanted to add even a bit of diffusion to this area to enhance the effect and achieve an even softer look.
But since diffuse and sharpen module, with which I wanted to add this diffusion, is hierarchically lower than contrast equalizer module, I had to move it above contrast equalizer to apply this diffusion after the reduction of local contrasts with contrast equalizer.
In the second photo from the video, I first colored the highlights (the lights) with the rgb primaries module first and then used diffuse and sharpen module to mimic the diffusion filter. So, I had to place the diffuse and sharpen module over the rgb primaries module to apply the diffusion after the coloring. In this way, the lights got a red glow caused by the diffusion of the previously red colored lamps.