Preprocessors

Use the following preprocessors to clean up your documents before extracting structured data. Preprocessors execute in the order you define them in an array.

Preprocessor	Image	Notes
Deskew		Corrects the alignment of PDF documents that are skewed, for example as a result of being photographed at an angle instead of straight on.
Ligature		Intelligently replaces Unicode ligatures in a PDF text extraction.
Merge Lines		Corrects oversplit lines.
OCR		Selectively OCRs pages in PDFs containing a mix of digitally generated text and text images (such as scanned text). If the whole PDF is a scan, you don't need to configure this preprocessor.
Page Filter		Filters out low-scoring pages given a bag of target terms and stop terms.
Page Range		Ignores pages outside the start page and end page.
Remove Header		Removes repeating elements at the top of the page. Ignores header elements that overlap with the page's main body.
Remove Footer		Removes repeating elements at the bottom of the page. Ignores footer elements that overlap with the page's main body.
Scale		Corrects the size of text in PDF documents whose size varies, for example as a result of being scanned or photographed at different scales.
Split Lines		Corrects undersplit lines.