Permission priming can help solve this problem by: Directing the user's awareness: Users know that a photo editing app needs camera access. Evidence shows that a reminder, directing the user's awareness to this fact, prepares them for the ask better. Tying access to value: Users sign up to do something specific. Let them know that you're only asking for access to help them achieve their goals.
When you "prime" users for an ask, you're explaining two things: why you're asking for something and how responding will benefit them. Both have strategic underpinnings: Communicating why you need the access directs the user's attention to what you need from them to deliver value, building trust. Focusing on the benefit reminds them they signed up to receive that value, building motivation.
Asking for permission breaks up the onboarding flow. The more natural the ask, the less jarring it is.
Don't ask for permission to use the camera until you need to use it, in other words. If you wait to ask for access to the camera when the user is all set to take a picture, they won't think twice about giving it the go-ahead.