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 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 text extraction.
Merge Lines		Corrects oversplit lines.
NLP	Advanced prompt configuration for each large language model (LLM)-based method in a config.
OCR		Selectively OCRs pages in documents 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 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.
Rotate page		In most cases, Sensible corrects page rotation automatically. If it doesn’t, configure this preprocessor.
Scale		Corrects the size of text in documents whose size varies, for example as a result of being scanned or photographed at different scales.
Split Lines		Corrects undersplit lines.