After the full-size preview support has opened up, this also opens up to the option of having a new category named Tools. Instead of Various which should be reserved for Custom Code series, and Games and Demos, filters that are actually not filter per se, but tools could be added to this new category ‘Tools’.
In addition, I have made some filters that can actually belong here, and I’m sure others have made something that belong in this thread as well.
Some of my own filters that are actually not filters:
Reverse Engineer Gradient Map
Reverse Engineer Color Curve
Premade Palette (This can be a filter, but really better as a tool)
I agree that the categories could use a revamp. E.g., there are filters under existing ones that don’t really belong to them but have nowhere else to go, except for Testing or Various.
I understand that David moderates the categories. Perhaps we could discuss this here: what they could be like and which filters should go where. Make a Wiki out of it where anyone can edit as a proposal to him.
I actually had attempted to make the minimal category version of the current category, and with comparison with Paint.NET with plugins. I can only merge Texture and Rendering into Texture & Rendering, and maybe Silhoutte could go under it. Or one could use Render to have subcategories such as Texture and Pattern. I ended up adding Object to make it clear that this is designed to work with images containing Alpha. Finally, I added Tools to make it easier to users to find filters that are actually not for applying directly on canvas.