What Is OCR and How Does It Work?
OCR is the technology behind converting images of text into editable text. Here's a clear, simple explanation of how it works.
What Is OCR?
OCR stands for Optical Character Recognition. It's a technology that allows computers to "read" text from images. Instead of just seeing a picture, an OCR engine analyzes the visual patterns in the image and identifies individual characters, words, and sentences.
A Brief History
OCR has existed since the 1950s, originally used for reading typed text on paper to allow computers to process physical documents. Today, OCR is embedded in smartphones, document scanners, banking apps, and online tools.
How Does OCR Work?
Modern OCR engines like Tesseract go through several stages:
1. Image Preprocessing
The image is cleaned up — converted to grayscale, contrast is increased, and any skew (rotation) is corrected. This makes characters easier to identify.
2. Layout Analysis
The engine identifies text regions, separates columns, finds line boundaries, and determines reading direction.
3. Character Segmentation
The text regions are broken into individual characters or character groups.
4. Character Recognition
Each character is compared against a trained model. Neural networks are now used for this step in modern OCR systems, greatly improving accuracy.
5. Post-Processing
The recognized text is passed through a spell-checker and language model to correct errors and improve output quality.
What Affects OCR accuracy?
- **Image resolution**: Higher DPI = better accuracy
- **Font type**: Standard fonts are easier to recognize
- **contrast**: Dark text on light background is ideal
- **Language**: Well-supported languages have better models
- **Noise**: Backgrounds, watermarks, and stains reduce accuracy
OCR in ConvertIQ
ConvertIQ uses Tesseract.js, the JavaScript/WebAssembly port of Google's open-source Tesseract OCR engine. It runs entirely in your browser, which means your images are never sent to any server.
Conclusion
OCR is a powerful, mature technology that unlocks the text in your images and scanned documents. Understanding how it works helps you get better results — better-quality images = more accurate text extraction.