Just thought I would share a sharpening option in Darktable that adds a bit of contrast boost to the image. I have saved this as a preset for easy use.
To use the highpass filter you select overlay blend mode and adjust the opacity or contrast boost to get the desired effect.
Turning on the module and setting sharpness to 15%
Set contrast boost to 40%
Set blend to uniformly
Set blend mode to overlay
Set the opacity to 50%
Save as preset and when this preset is applied to images experimenting with the sliders allows fine-tuning. Increasing the sharpness gives more detail. The opacity slider affects the strength of the module. I find opacity settings of 25 or 50% can be helpful for underwater images which benefit from the boost in contrast.
You just have to be careful about halos when you want/need to push the sharpness. I used to use something similar, but find the newer methods less prone to artifacts (e.g. ‘contrast equaliser’ or ‘diffuse or sharpen’). Also, local contrast enhancements can handle part of the contrast boost.
Then again, any method that increases edge contrast can cause artifacts if pushed too much, and whether the effect is visible will also depend on the export size…
Totally agree. This method is not suited to every image, but it works nice when a little extra contrast is desired. Sometimes artefacts appear in extreme highlights and then this method has to then be avoided. Currently working with underwater images taken at Conflict Island in PNG and this method is working nice for most images.
I have a couple of tone curve presets that I blend in subtract at low opacity… I use these for contrast bump…they work a bit like dehaze but the effect can be tweaked a little more. I will add these and there is no real issue with halos…
