ArchiNode

How do I change one element without redoing the whole render?

With an editing model: they start from a base image and change what you ask while leaving the rest of the frame as it is. Qwen 3 Edit and Boogu Edit are available from Basic; Seedream 5, from Standard. GPT Image PRO and Turbo are also very good at editing a finished render.

Each model uses a maximum number of images, counting the base; any extra ones aren't used:

ModelBase imageImages it usesExtra charge
NanoBanana PRO and TurboOptionalUp to 10—
GPT Image PRO and TurboOptionalUp to 4+5 tokens for each image after the first
Seedream 5RequiredUp to 10+5 tokens for each image after the first
Seedream 4OptionalUp to 10—
Flux 2OptionalUp to 16—
Qwen 3 EditRequiredUp to 3 (the base and 2 references)—
Boogu EditRequiredOnly the base—

In Canvas AI, marked areas travel as one more image and count toward that maximum. To edit a specific area precisely, paint the mask in the “Retouch” tab of the Nodes image editor.

AI models