Via Google Translate (which seems to have done a pretty decent job here):
In practice
If the subject of a photograph or video is a person, it has the right to object to the use of his image.
However, the legislation distinguishes two cases:
if the person photographed or filmed in a recognizable manner in a public or private, permission is required before any public disclosure regardless of the support (in the press, in a book, a poster or a flyer on a site Internet or television)
if the snapshot does not recognize the person (especially if it is melted into the crowd), consent is not required.
Note: If you participate in a public event and you are photographed in the parade, the image may be published in the press without your consent under Right to Information.
Application of image rights and sanctions
Before disseminating an image of a person, the broadcaster must obtain permission from the person concerned. The person must give their express consent, that is to say, it must make its written consent.
As for the images of minors, the consent of both parents is required.
Otherwise, the person whose image has been disclosed may sue and seize the judge. It will take all steps (sequestration, seizure, etc.) clean to prevent or stop an invasion of privacy
The penalty may take the form of damages. In addition, offenders face a year's imprisonment and a fine of 45,000 euros (according to Article 226-1 of the Penal Code) because the violation of this law is a criminal offense.
Exceptions to the right of publicity
There are exceptions for public figures in the exercise of their function (politician attending a meeting, ministers at the exit of the Council of Ministers or celebrities mounted the steps of the Cannes Festival, for example ...).
A picture taken in the context of professional or public person may be distributed without permission if it is used for current or historical work and does not violate human dignity.
However, if the photograph was taken in the context of private life (on the beach during the holidays), a model release is again essential.
****
In law, the French have far stricter privacy rights than in the UK - see
here. But the chances are you'll be OK for basic snappery not intended for commercial use.