Comparing On-device OCR: Apple Vision vs Google MLKit
Author: Erik Großkopf, bitfactory.io Date: June 30, 2021 Test device: iPhone 12
Key Findings
Speed
- MLKit average: ~0.05s per image
- Apple Vision average: ~0.31s per image
- MLKit is 6x faster
Low-resolution text
- MLKit slightly better at 125×125 px
- Both frameworks similar track overall
- Downsampling recommended to save time beyond certain resolution
Rotated text
- No degradation up to 20° for both
- After 20°, Apple Vision slightly outperforms MLKit
API differences
- Apple Vision: fast/accurate modes, confidence values, custom words, language correction
- MLKit: simple API returning text blocks with bounding boxes; language detection
Conclusion
Both free, on-device. MLKit wins on speed (6x) and cross-platform. Vision wins on rotated text and API features (though author found confidence values “pretty useless”). If speed is critical (e.g. camera preview OCR), prefer MLKit.
Test project: https://github.com/ErikGro/OCR-Comparison