Image changes format after publishing

[Amata]

This also relates to the background image of www.puebloartesano.es.

I have it in my project as an jpg of 200/300 kb, but somehow when I publish it it shows up as an png of 6,5 mb, it has the same name, but I never had an png with that name. Any ideas?

[Pablo]

Maybe you have applied effects or filters to the image?

[Amata]

Maybe you have applied effects or filters to the image?

Didn´t think so and I couldn´t find any, but you must have been right, because instead of replacing the image I deleted it and reinserted it and now the problem is fixed!
As always thank you very much for your quick and usefull help!