Smoothing jagged edge

[DynV]

I have some images with jagged edge; I made the background transparent and it was contrasting so I could leave little of the color fading in the result and the border not being gradual is obvious. I'd like to have the jagged edge smooth.

My first thought was anti-aliasing but I'm not sure GIMP have that and I wouldn't know what the best or most efficient way to go about with that. I did a search and the only relevant page I found was Fixing Jagged Image Edges with Gimp | Jafty Interactive Web Development, which I wonder if there's a better method.

Thank you kindly for your help

[Espermaschine]

It depends on the image.
For simple shapes you could alpha select, convert selection into a path and stroke the path.

[Ofnuts]

(12-18-2017, 03:44 PM)DynV Wrote: I have some images with jagged edge; I made the background transparent and it was contrasting so I could leave little of the color fading in the result and the border not being gradual is obvious. I'd like to have the jagged edge smooth.

My first thought was anti-aliasing but I'm not sure GIMP have that and I wouldn't know what the best or most efficient way to go about with that. I did a search and the only relevant page I found was Fixing Jagged Image Edges with Gimp | Jafty Interactive Web Development, which I wonder if there's a better method.

Thank you kindly for your help

You don't smooth a jagged edge, you avoid creating it in the first place. Since you say "I made the background transparenr" I'm ready to bet that you just did a wand-selected+[delete]? That would explain why you get a jagged edge. A much better technique to get a clean edge is:

• Wand-select the background with a reasonable threshold (around 15)
  
•  Select>Grow by two pixels
  
• Color>Color to alpha and remove the background (an equivalend method is to bucket-fill the selection with the background color, after setting the bucket-fill tool in "Color erase" mode.