This is a work in progress and sudden, dramatic changes are expected!
FreeLens
This project provides a reference implementation of NaviLens and ddTag for educational or personal use. Commercial use is at your own risk as NaviLens and ddTag may attempt to enforce their IP.
Documentation
- NaviLens
- ddTag specification
- ddTag detection
- CRCs in ddTags
- Testing NaviLens code PDFs
- Tag editor
- Development
Quickstart
Installation
pip install freelens
Generating Tags
FreeLens generates 5×5, 7×7, 9×9, and 11×11 tags. The 5×5 generator uses the CRC found in deployed NaviLens tags. Larger generators extend that calculation with the CRC width and polynomial for their size. Their CRCs are not validated because no deployed examples have been tested.
from freelens import Tag
message = "101010101011000000001011"
tag = Tag.from_message(message, n=5)
tag_img = tag.to_image()
tag_img.save("tag.png")
Generated tags larger than 5×5 report an unknown CRC status:
tag = Tag.from_message("0" * 64, n=7)
assert tag.crc_valid is None
Detecting Tags
from freelens import detect_tags
from PIL import Image
img = Image.open("dataset/images/0001.jpg")
tags_list = detect_tags(
img,
n=5,
validate_crc=True,
require_valid_crc=True,
)
for tag in tags_list:
print(tag.message)
1 maintainer
Metadata
1 maintainer
Release files for freelens 0.0.5
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Source distribution (sdist)
| File | Size | Uploaded | Provenance | |
|---|---|---|---|---|
| freelens-0.0.5.tar.gz | 7.3 kB | With provenance | Details |
Built distribution (wheel)
| File | Interpreter | ABI | Platform | Reset |
|---|---|---|---|---|
| freelens-0.0.5-py3-none-any.whl | Python 3 | none | any | Details |
Total release size: 14.8 kB
Release files / freelens-0.0.5.tar.gz
| Download URL | freelens-0.0.5.tar.gz |
|---|---|
| Size | 7.3 kB |
| Tags | Source |
|
SHA-256 checksum How to use checksums |
85fc705f0fde9c0dd20efd3d3017270ecb09da5bb70fe54ad5d52ef2f9771b26
|
|
BLAKE2b-256 checksum How to use checksums |
3a82fee47a11e8dff7a96012b45a1933253562a2b1f6d01104dd6c740ce00e03
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
|
Provenance
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Transparency logRelease files / freelens-0.0.5-py3-none-any.whl
| Download URL | freelens-0.0.5-py3-none-any.whl |
|---|---|
| Size | 7.5 kB |
| Tags | Python 3 |
|
SHA-256 checksum How to use checksums |
946c614636ba1dafc93af5362dff5f12b9e8d85b33ec6b4b942fce7cdf46eb4a
|
|
BLAKE2b-256 checksum How to use checksums |
48859ee30fef797cebaa95bcd5cd553d3d09f83a59805288e19bd1f58a23347f
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
|
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
PyPI Publish Attestation
PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Aug 24, 2026.
Transparency logSecurity for freelens 0.0.5
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
Full provenance
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Attestation for freelens-0.0.5.tar.gz
PyPI Publish Attestation
PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Aug 24, 2026.
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