Members are in complete control of your photos. They can choose to have their photos Blurred to all members. They can then choose to reveal their photos to a specific match at a time their your choosing (in the Chat tap the top right menu button and tap
Once unmatched or blocked your photos revert back to being Blurred automatically.
Both are optional however and are not recommended. Profiles with Visible photos receive 300% more matches and are unmatched less.
To change your Photo privacy go to
⚙ Menu → Edit Profile → My Photos and amend the bottom option Private or Visible).