Comment by TheDong

The author is trying to integrate with the Go stdlib, which requires you produce images from an 'io.Reader". See https://pkg.go.dev/image#RegisterFormat

Isn't using the stdlib simpler than not for your callers?

I also often hear gophers say to take inspiration from the go stdlib. The 'net/http' package's 'http.Request.Body' also has this same UX. Should there be `Body` and `BodyBytes` for the case when your http request wants to refer to a reader, vs wants to refer to bytes you already have?