Transformation d'une Sélection lisse ou progressive en une sélection nette

How do I change a progressive or smoothed selection to a sharp selection? 

By @jean baptistep86491065

I'm not sure what "progressive" or "smoothed" means, but it might be a translation issue.

If your selection has feathering, for instance, you might try this:

• Enter Quick Mask mode "Q"
• Open Levels "Cmd+L"
• Drag both the left and right sliders to a flat area, watching until the feathering is removed > Click OK
• Exit Quick Mask mode "Q" to return to your selection

If you mean something else, please clarify and show screenshots.

Apologies for the 2-day delay in seeing your post.

Jane