Optionalerrorthrow rejects on failure (default); collect returns partial results with diagnostics.
OptionalocrDefaults to auto when a provider was supplied, otherwise off. Explicit auto/always requires a provider.
OptionalonCalled during work. Keep callbacks lightweight and avoid throwing.
OptionalpagesOne-based pages to extract; omitted means all pages.
OptionalsignalAborts queued work promptly; a synchronous engine decode already running may finish before cleanup.
Page selection, OCR policy and behavior when individual page or OCR-region operations fail.