As best I can determine, royalties you receive are not taxable in California if you are not a California resident, even if the photos that earn the royalties were taken while you were previously a California resident. This ruling seems to be on topic.
https://www.ftb.ca.gov/tax-pros/law/legal-rulings/1958-145.html
However, you should know that if you perform new work as an independent contractor for a customer in California, that is California taxable income even though you do not live or work in California, as long as your customer is in California. That could mean that if you are contracted by a California client to provide new photographs, that will be taxable in California (for example, a California travel agent wants you to take photos of a new cruise ship docked in Florida that they can use to advertise trips).
