[Gimp-docs] Color to alpha

[Julien Hardelin <jhardlin orange fr>]

Hi,

I am trying to update Color to alpha, but I don't understand 
transparency and opacity thresholds.

Pop-up helps mention a limit that I suppose to be a transparency limit. 
"below" and "above" seem to me inverted.

I don't see how to describe these options.

Please give me explanations with, as much as possible, examples.

Julien