GroupDocs.Redaction supports both types of image documents for Optical Character Recognition (OCR):
image files, such as printed document scans (PNG, JPG, etc.) embedded images within office documents (PDF, DOCX, etc.) You have to implement IOcrConnector interface and pass the instance to RedactorSettings constructor.
For more details, see OCR Usage Basics article.
OCR usage limitations There are the following limitations of the OCR with GroupDocs.Redaction v21.3:
textual replacements are not supported, so you have to use color box replacements to redact text in images.... Spreadsheets, HTML and Markdown document...