Thanks for your reply.
I did a test with 'guvcview', and the picture is OK.
After that, I started Skypeforlinux, nothing changed.
In 'guvcview', i turn on 'vertical flip' parameter,the picture appears upside down.
I restarted Skypeforlinux, and the picture appears upside-down.
I have searched in différent forums, the problem is well knowned and seems to be present only with Asus notebooks. The problem is not in LinuxLite.
Let me the time to run a test on mys wife's Toshiba notebook and I will come to give you feedback.