Skip to content

nd2.tiff

Functions for converting .nd2 to .tiff files.

Functions:

  • nd2_to_tiff

    Export an ND2 file to an (OME)-TIFF file.

nd2_to_tiff

nd2_to_tiff(source: str | PathLike | ND2File, dest: str | PathLike, *, include_unstructured_metadata: bool = True, progress: bool = False, on_frame: Callable[[int, int, dict[str, int]], None] | None = None, modify_ome: Callable[[OME], None] | None = None) -> None

Export an ND2 file to an (OME)-TIFF file.

To include OME-XML metadata, use extension .ome.tif or .ome.tiff.

https://docs.openmicroscopy.org/ome-model/6.3.1/ome-tiff/specification.html

Parameters:

  • source

    (str | PathLike | ND2File) –

    The ND2 file path or an open ND2File object.

  • dest

    (str | PathLike) –

    The destination TIFF file.

  • include_unstructured_metadata

    ( bool, default: True ) –

    Whether to include unstructured metadata in the OME-XML. This includes all of the metadata that we can find in the ND2 file in the StructuredAnnotations section of the OME-XML (as mapping of metadata chunk name to JSON-encoded string). By default True.

  • progress

    (bool, default: False ) –

    Whether to display progress bar. If True and tqdm is installed, it will be used. Otherwise, a simple text counter will be printed to the console. By default False.

  • on_frame

    (Callable[[int, int, dict[str, int]], None] | None, default: None ) –

    A function to call after each frame is written. The function should accept three arguments: the current frame number, the total number of frames, and a dictionary of the current frame's indices (e.g. {"T": 0, "Z": 1}) (Useful for integrating custom progress bars or logging.)

  • modify_ome

    (Callable[[OME], None], default: None ) –

    A function to modify the OME metadata before writing it to the file. Accepts an ome_types.OME object and should modify it in place. (reminder: OME-XML is only written if the file extension is .ome.tif or .ome.tiff)

Source code in nd2/tiff.py
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
def nd2_to_tiff(
    source: str | PathLike | ND2File,
    dest: str | PathLike,
    *,
    include_unstructured_metadata: bool = True,
    progress: bool = False,
    on_frame: Callable[[int, int, dict[str, int]], None] | None = None,
    modify_ome: Callable[[ome_types.OME], None] | None = None,
) -> None:
    """Export an ND2 file to an (OME)-TIFF file.

    To include OME-XML metadata, use extension `.ome.tif` or `.ome.tiff`.

    <https://docs.openmicroscopy.org/ome-model/6.3.1/ome-tiff/specification.html>

    Parameters
    ----------
    source : str | PathLike | ND2File
        The ND2 file path or an open ND2File object.
    dest : str  | PathLike
        The destination TIFF file.
    include_unstructured_metadata :  bool
        Whether to include unstructured metadata in the OME-XML. This includes all of
        the metadata that we can find in the ND2 file in the StructuredAnnotations
        section of the OME-XML (as mapping of metadata chunk name to JSON-encoded
        string). By default `True`.
    progress : bool
        Whether to display progress bar.  If `True` and `tqdm` is installed, it will
        be used. Otherwise, a simple text counter will be printed to the console.
        By default `False`.
    on_frame : Callable[[int, int, dict[str, int]], None] | None
        A function to call after each frame is written. The function should accept
        three arguments: the current frame number, the total number of frames, and
        a dictionary of the current frame's indices (e.g. `{"T": 0, "Z": 1}`)
        (Useful for integrating custom progress bars or logging.)
    modify_ome : Callable[[ome_types.OME], None]
        A function to modify the OME metadata before writing it to the file.
        Accepts an `ome_types.OME` object and should modify it in place.
        (reminder: OME-XML is only written if the file extension is `.ome.tif` or
        `.ome.tiff`)
    """
    dest_path = Path(dest).expanduser().resolve()
    output_ome = ".ome." in dest_path.name

    # normalize source to an open ND2File, and remember if we opened it
    close_when_done = False
    if isinstance(source, (str, PathLike)):
        from ._nd2file import ND2File

        nd2f = ND2File(source)
        close_when_done = True
    else:
        nd2f = source
        if close_when_done := nd2f.closed:
            nd2f.open()

    try:
        # map of axis_name -> size
        sizes = dict(nd2f.sizes)

        # pop the number of positions from the sizes.
        # The OME data model does best with 5D data, so we'll write multi-5D series
        n_positions = sizes.pop(AXIS.POSITION, 1)

        # join axis names as a string, and get shape of the data without positions
        axes, shape = zip(*sizes.items())
        # U (Unknown) -> Q : other (OME)
        metadata = {"axes": "".join(axes).upper().replace(AXIS.UNKNOWN, "Q")}

        # Create OME-XML
        ome_xml: bytes | None = None
        if output_ome:
            if nd2f.is_legacy:
                warnings.warn(
                    "Cannot write OME metadata for legacy nd2 files."
                    "Please use a different file extension to avoid confusion",
                    stacklevel=2,
                )
            else:
                # get the OME metadata object from the ND2File
                ome = nd2_ome_metadata(
                    nd2f,
                    include_unstructured=include_unstructured_metadata,
                    tiff_file_name=dest_path.name,
                )
                if modify_ome:
                    # allow user to modify the OME metadata if they want
                    modify_ome(ome)
                ome_xml = ome.to_xml(exclude_unset=True).encode("utf-8")

        # total number of frames we will write
        tot = nd2f._frame_count
        # create a progress bar if requested
        pbar = _pbar(total=tot, desc=f"Exporting {nd2f.path}") if progress else None

        # `p_groups` will be a map of {position index -> [(frame_number, f_index) ...]}
        # where frame_number is passed to read_frame
        # and f_index is a map of axis name to index (e.g. {"T": 0, "Z": 1})
        # positions are grouped together so we can write them to the tiff file in order
        p_groups: defaultdict[int, list[tuple[int, dict[str, int]]]] = defaultdict(list)
        for f_num, f_index in enumerate(nd2f.loop_indices):
            p_groups[f_index.get(AXIS.POSITION, 0)].append((f_num, f_index))

        # create a function to iterate over all frames, updating pbar if requested
        def position_iter(p: int) -> Iterator[np.ndarray]:
            """Iterator over frames for a given position."""
            for f_num, f_index in p_groups[p]:
                # call on_frame callback if provided
                if on_frame is not None:
                    on_frame(f_num, tot, f_index)

                # yield the frame and update the progress bar
                yield nd2f.read_frame(f_num)
                if pbar is not None:
                    pbar.set_description(repr(f_index))
                    pbar.update()

        # if we have ome_xml, we tell tifffile not to worry about it (ome=False)
        tf_ome = False if ome_xml else None
        # Write the tiff file
        pixelsize = nd2f.voxel_size().x
        photometric = tf.PHOTOMETRIC.RGB if nd2f.is_rgb else tf.PHOTOMETRIC.MINISBLACK
        with tf.TiffWriter(dest_path, bigtiff=True, ome=tf_ome) as tif:
            for p in range(n_positions):
                tif.write(
                    iter(position_iter(p)),
                    shape=shape,
                    dtype=nd2f.dtype,
                    resolution=(1 / pixelsize, 1 / pixelsize),
                    resolutionunit=tf.RESUNIT.MICROMETER,
                    photometric=photometric,
                    metadata=metadata,
                    description=ome_xml,
                )

        if pbar is not None:
            pbar.close()

    finally:
        # close the nd2 file if we opened it
        if close_when_done:
            nd2f.close()