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Transformations with thresholds : feathering to smoothen transition artifacts
Posted: November 30th, 2021, 9:56 am
by pierrelabreche
For example, when using Multi-pass sharpening with blur and sharpen thresholds :
Is there a way to avoid the grainy artifacts at the transition between zones defined by thresholds ?
If not, would it be possible to implement feathering in those transformations, with feathering control in the dialog box ?
Re: Transformations with thresholds : feathering to smoothen transition artifacts
Posted: December 1st, 2021, 8:54 pm
by jsachs
In those cases where I have implemented this I have found it does not work nearly as well as one might wish. Another approach to deal with this is to create a mask using the Mask Texture Tool and use this to sharpen only textured areas. By using a mask you have a lot of processing options such as feathering and blurring as well as fine tuning what level of texture you want to detect.
Re: Transformations with thresholds : feathering to smoothen transition artifacts
Posted: December 2nd, 2021, 12:08 pm
by pierrelabreche
I was thinking of feathering or blurring as found in the Gray Zone transformations.
Multi-pass sharpening
- 2021-12-02 Multi-pass sharpen grainy artifacts v1.jpg (105.46 KiB) Viewed 1646 times
Three-zone adjustment
Before blurring, the transitions are grainy.
- 2021-12-02 Three-zone adjustment with grainy artifacts before blurring.png (302.12 KiB) Viewed 1646 times
After blurring, the transitions are smooth.
- 2021-12-02 Three-zone adjustment, after blurring, without grainy artifacts v1.jpg (108.59 KiB) Viewed 1646 times
Re: Transformations with thresholds : feathering to smoothen transition artifacts
Posted: December 2nd, 2021, 12:16 pm
by pierrelabreche
jsachs wrote: ↑December 1st, 2021, 8:54 pm
In those cases where I have implemented this I have found it does not work nearly as well as one might wish. Another approach to deal with this is to create a mask using the Mask Texture Tool and use this to sharpen only textured areas. By using a mask you have a lot of processing options such as feathering and blurring as well as fine tuning what level of texture you want to detect.
Actually, if the goal is local area contrast enhancement to a soft-textured area such as a cloudy sky, I expect that textured-based masking will be of little help.
Also consider that the area of interest is defined by blurring and sharpening thresholds, so a mask will have to be re-done whenever the threshold sliders are adjusted.