---
title: "What is OCR?"
description: "OCR, optical character recognition, turns pixels of text — scans, screenshots, photos — into strings."
url: "https://pixeltable.com/learn/what-is-ocr"
updated: "2026-09-29"
vertical: "Documents"
doc: "https://docs.pixeltable.com/sdk/latest/gemini#udf-generate_content"
---

# What is OCR?

OCR, optical character recognition, turns pixels of text — scans, screenshots, photos — into strings.

Updated: 2026-09-29


## On this page

- [How it works](https://pixeltable.com/learn/what-is-ocr#how-it-works)
- [What it is not](https://pixeltable.com/learn/what-is-ocr#what-it-is-not)
- [Comparison](https://pixeltable.com/learn/what-is-ocr#comparison)
- [Where Pixeltable fits](https://pixeltable.com/learn/what-is-ocr#where-pixeltable-fits)
- [Questions](https://pixeltable.com/learn/what-is-ocr#questions)

## How it works {#how-it-works}


- The input is an image or a scanned page.
- A model reads the glyphs and writes text.
- That text can then be chunked and searched like any other string.

## What it is not {#what-it-is-not}

It is not extracting text already embedded in a digital PDF, and it is not captioning a scene.

## OCR: this, and the thing it is confused with {#comparison}

|  | This | Not this |
| --- | --- | --- |
| Input | Pixels of writing | A digital PDF with a text layer |
| Output | Characters | A description of the picture |
| Next step | Index the string | Stop at the image |

## Where Pixeltable fits {#where-pixeltable-fits}

Pixeltable runs OCR as a computed column on an image or document. The string it writes is what later search uses.

## Questions {#questions}

### How does OCR work? {#faq-1}

The input is an image or a scanned page. A model reads the glyphs and writes text. That text can then be chunked and searched like any other string.

### What is OCR often confused with? {#faq-2}

It is not extracting text already embedded in a digital PDF, and it is not captioning a scene.

## In the blog

- [Build Production Document RAG Pipelines with Pixeltable](https://pixeltable.com/blog/document-pdf-processing-rag-pixeltable)

## Related

- [Documentation](https://docs.pixeltable.com/sdk/latest/gemini#udf-generate_content)
- [Build Production Document RAG Pipelines with Pixeltable](https://pixeltable.com/blog/document-pdf-processing-rag-pixeltable)
- [image-to-text](https://pixeltable.com/tools/image-to-text)
- [pdf-to-text](https://pixeltable.com/tools/pdf-to-text)