sdtfile 2026.7.12

Read Becker & Hickl SDT files

Sdtfile is a Python library to read SDT files produced by Becker & Hickl SPCM software. SDT files contain time correlated single photon counting instrumentation parameters and measurement data. Currently only the “Setup & Data”, “DLL Data”, and “FCS Data” formats are supported.

Becker & Hickl GmbH is a manufacturer of equipment for photon counting.

Author:

Christoph Gohlke

License:

BSD-3-Clause

Version:

2026.7.12

DOI:

10.5281/zenodo.10125608

Quickstart

Install the sdtfile package and all dependencies from the Python Package Index:

python -m pip install -U sdtfile[all]

See Examples for using the programming interface.

Source code and support are available on GitHub.

Requirements

This revision was tested with the following requirements and dependencies (other versions may work):

• CPython 3.12.10, 3.13.14, 3.14.6, 3.15.0b3 64-bit

• Numpy 2.5.1

• Imagecodecs 2026.6.26 (optional for LZ4 compressed data blocks)

Revisions

2026.7.12

• Fix BlockNo attribute names (breaking).

• Try power-of-two padded image shapes when block/adc_re > image_y * image_x.

• Support LZ4 compressed and larger than 4 GB data blocks (not tested).

• Update MeasureInfoExt structure with MeasStopInfoExt and MWL fields.

• Use BinaryFile for file I/O.

• Add simple CLI to preview data and metadata in SDT files.

2026.6.29

• Fix reading SDT files with truncated embedded ZIP files (#8).

2026.6.6

• Fix potential file handle leak in SdtFile init.

• Add options for memory-mapping and locked reading to BinaryFile.

• Add option to memory-map SDT files.

• Drop support for Python 3.11 and numpy 2.0 (SPEC0).

• Support Python 3.15.

2026.2.8

• Derive SdtFile from BinaryFile (breaking).

• Rename MEASURE_INFO.MeasHISTInfo to HISTInfo to match C struct (breaking).

• Revise shaping of FCS_BLOCK data (breaking).

• Fix code review issues.

2026.1.14

• Improve code quality.

2025.12.12

• Add new SPC modules and MEASURE_INFO_EXT fields.

• Drop support for Python 3.10.

2025.5.10

• …

Refer to the CHANGES file for older revisions.

References

1. W Becker. The bh TCSPC Handbook. 9th Edition. Becker & Hickl GmbH 2021. pp 879.

2. SPC_data_file_structure.h header file. Part of the Becker & Hickl SPCM software installation.

Examples

Read image and metadata from an “SPC Setup & Data File”:

>>> sdt = SdtFile('image.sdt')
>>> int(sdt.header.revision)
588
>>> sdt.info.id[1:-1]
'SPC Setup & Data File'
>>> int(sdt.measure_info[0].scan_x)
128
>>> len(sdt.data)
1
>>> sdt.data[0].shape
(128, 128, 256)
>>> sdt.times[0].shape
(256,)
>>> sdt.close()

Read data and metadata from an “SPC Setup & Data File” with multiple data sets:

>>> sdt = SdtFile('fluorescein.sdt')
>>> len(sdt.data)
4
>>> sdt.data[3].shape
(1, 1024)
>>> sdt.times[3].shape
(1024,)
>>> int(sdt.setup.bh_bin_hdr['soft_rev'])
850
>>> sdt.close()

Read image data from an “SPC FCS Data File” as numpy array:

>>> sdt = SdtFile('fcs.sdt')
>>> sdt.info.id[1:-1]
'SPC FCS Data File'
>>> len(sdt.data)
1
>>> sdt.data[0].shape
(512, 512, 256)
>>> sdt.times[0].shape
(256,)
>>> sdt.close()

View the image and metadata in an SDT file from the console:

$ python -m sdtfile image.sdt