I believe this is how The Cambridge Grammar of the English Language suggests we analyze your sentence:
The subject is a non-finite subordinate clause, setting a stable parameter matching with entire scene. It's marked as subordinate by having no overt subject and by having the verb in gerund-participle form (-ing form), which is a non-finite form. Gerund-participial clauses commonly function as subjects.
(CGEL doesn't distinguish between the gerund and participle uses of the -ing form. More traditionally, we could say this is the gerund form of the verb; gerund is a term from traditional grammar that refers to the form of a verb that can appear where a noun is expected.)
You can't generalize that "phrases can be subjects". It's true that some phrases can. But we can see that it's not always true; for example, preposition phrases are generally not able to function as subjects.
The subject of your sentence is fine. However, entire scene needs an article: I'd write the entire scene.