getDetectLanguagePageFraction

The share of a page (0.0 to 1.0) the automatic language-detection pass reads text from — a centered band of the page, full width. Identifying a language needs a couple of paragraphs, while the pass otherwise recognizes the whole page, and recognition cost scales with the amount of text read. A band that yields too little text falls back to the whole page, so this trades a rare second read for a much cheaper common case. Orientation and script detection always read the whole page. Set to 0 to read text from the whole page.