Thanks very much!
https://willus.com/k2pdfopt/help/options.shtml
-mode copy: source pages are simply copied to the output file, but rendered as bitmaps. No trimming or re-sizing is done.
-odpi 200: Set pixels per inch of output screen.
-ocr t: Attempt to use optical character recognition (OCR) in order to embed searchable text into the output PDF document. If followed by t or g, specifies the ocr engine to use (tesseract or gocr).
-ocrlang <set language>: Select the Tesseract OCR Engine language. […] The default language is whatever is in your Tesseract trained data folder. […] Use -ocrlang ? to see the list of Tesseract language files in your Tesseract data folder.
-ocrd p: Set OCR detection type for k2pdfopt and Tesseract. […] For -ocrd p, k2pdfopt passes the entire output page of text to Tesseract and lets Tesseract parse it for word positions.