switch header

README.md

examples/generated/example_header.json

examples/generated/example_projection.json

examples/generated/example_roi.json

examples/generated/example_volume.json

scripts/generate_example_data.py

scripts/validate_file.py

src/thd_json/header/header.json

src/thd_json/image/image.json

src/thd_json/projection/projection.json

src/thd_json/projection_geometry/projection_geometry.json

src/thd_json/validation.py

src/thd_json/volume/volume.json