Photos Module

[MurielleG14]

Hi,

I am new to Python and struggling with the Image/Photos modules.
So far, I have managed to select a photo from photoroll, access pixels, save it, copy it...
My problem is that I cannot figure out how to save the picture as a png to the photoroll. No matter what I do, I end up with a jpeg and when I read it again, the pixel values are not what I expect. This only happens when saving to the photoroll. The saves to pasteboard and local file system do not behave this way.
What am I doing wrong ? Maybe some extra arguments to the photos.save_image ?
Thanks for your help.