You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
285 lines
11 KiB
285 lines
11 KiB
# -*- coding: utf-8 -*-
|
|
import struct
|
|
|
|
import array
|
|
import six
|
|
from pims import Frame
|
|
import numpy as np
|
|
|
|
from nd2reader.common import get_version, read_chunk
|
|
from nd2reader.exceptions import InvalidVersionError, NoImageError
|
|
from nd2reader.label_map import LabelMap
|
|
from nd2reader.raw_metadata import RawMetadata
|
|
|
|
|
|
class Parser(object):
|
|
"""Parses ND2 files and creates a Metadata and driver object.
|
|
|
|
"""
|
|
CHUNK_HEADER = 0xabeceda
|
|
CHUNK_MAP_START = six.b("ND2 FILEMAP SIGNATURE NAME 0001!")
|
|
CHUNK_MAP_END = six.b("ND2 CHUNK MAP SIGNATURE 0000001!")
|
|
|
|
supported_file_versions = {(3, None): True}
|
|
|
|
def __init__(self, fh):
|
|
self._fh = fh
|
|
self._label_map = None
|
|
self._raw_metadata = None
|
|
self.metadata = None
|
|
|
|
# First check the file version
|
|
self.supported = self._check_version_supported()
|
|
|
|
# Parse the metadata
|
|
self._parse_metadata()
|
|
|
|
def calculate_image_properties(self, index):
|
|
"""Calculate FOV, channels and z_levels
|
|
|
|
Args:
|
|
index(int): the index (which is simply the order in which the image was acquired)
|
|
|
|
Returns:
|
|
tuple: tuple of the field of view, the channel and the z level
|
|
|
|
"""
|
|
field_of_view = self._calculate_field_of_view(index)
|
|
channel = self._calculate_channel(index)
|
|
z_level = self._calculate_z_level(index)
|
|
return field_of_view, channel, z_level
|
|
|
|
def get_image(self, index):
|
|
"""
|
|
Creates an Image object and adds its metadata, based on the index (which is simply the order in which the image
|
|
was acquired). May return None if the ND2 contains multiple channels and not all were taken in each cycle (for
|
|
example, if you take bright field images every minute, and GFP images every five minutes, there will be some
|
|
indexes that do not contain an image. The reason for this is complicated, but suffice it to say that we hope to
|
|
eliminate this possibility in future releases. For now, you'll need to check if your image is None if you're
|
|
doing anything out of the ordinary.
|
|
|
|
Args:
|
|
index(int): the index (which is simply the order in which the image was acquired)
|
|
|
|
Returns:
|
|
Frame: the image
|
|
|
|
"""
|
|
field_of_view, channel, z_level = self.calculate_image_properties(index)
|
|
channel_offset = index % len(self.metadata["channels"])
|
|
image_group_number = int(index / len(self.metadata["channels"]))
|
|
frame_number = self._calculate_frame_number(image_group_number, field_of_view, z_level)
|
|
try:
|
|
timestamp, image = self._get_raw_image_data(image_group_number, channel_offset, self.metadata["height"],
|
|
self.metadata["width"])
|
|
except (TypeError, NoImageError):
|
|
return Frame([], frame_no=frame_number, metadata=self._get_frame_metadata())
|
|
else:
|
|
return image
|
|
|
|
def get_image_by_attributes(self, frame_number, field_of_view, channel_name, z_level, height, width):
|
|
"""Gets an image based on its attributes alone
|
|
|
|
Args:
|
|
frame_number: the frame number
|
|
field_of_view: the field of view
|
|
channel_name: the color channel name
|
|
z_level: the z level
|
|
height: the height of the image
|
|
width: the width of the image
|
|
|
|
Returns:
|
|
Frame: the requested image
|
|
|
|
"""
|
|
image_group_number = self._calculate_image_group_number(frame_number, field_of_view, z_level)
|
|
try:
|
|
timestamp, raw_image_data = self._get_raw_image_data(image_group_number, self._channel_offset[channel_name],
|
|
height, width)
|
|
except (TypeError, NoImageError):
|
|
return Frame([], frame_no=frame_number, metadata=self._get_frame_metadata())
|
|
else:
|
|
return raw_image_data
|
|
|
|
@staticmethod
|
|
def get_dtype_from_metadata():
|
|
"""Determine the data type from the metadata.
|
|
|
|
For now, always use float64 to prevent unexpected overflow errors when manipulating the data (calculating sums/
|
|
means/etc.)
|
|
|
|
"""
|
|
return np.float64
|
|
|
|
def _check_version_supported(self):
|
|
"""Checks if the ND2 file version is supported by this reader.
|
|
|
|
Returns:
|
|
bool: True on supported
|
|
|
|
Raises:
|
|
InvalidVersionError: Raises an error if the version is unsupported
|
|
|
|
"""
|
|
major_version, minor_version = get_version(self._fh)
|
|
supported = self.supported_file_versions.get((major_version, minor_version)) or \
|
|
self.supported_file_versions.get((major_version, None))
|
|
|
|
if not supported:
|
|
raise InvalidVersionError("No parser is available for that version.")
|
|
|
|
return supported
|
|
|
|
def _parse_metadata(self):
|
|
"""Reads all metadata and instantiates the Metadata object.
|
|
|
|
"""
|
|
# Retrieve raw metadata from the label mapping
|
|
self._label_map = self._build_label_map()
|
|
self._raw_metadata = RawMetadata(self._fh, self._label_map)
|
|
self.metadata = self._raw_metadata.__dict__
|
|
|
|
def _build_label_map(self):
|
|
"""
|
|
Every label ends with an exclamation point, however, we can't directly search for those to find all the labels
|
|
as some of the bytes contain the value 33, which is the ASCII code for "!". So we iteratively find each label,
|
|
grab the subsequent data (always 16 bytes long), advance to the next label and repeat.
|
|
|
|
Returns:
|
|
LabelMap: the computed label map
|
|
|
|
"""
|
|
self._fh.seek(-8, 2)
|
|
chunk_map_start_location = struct.unpack("Q", self._fh.read(8))[0]
|
|
self._fh.seek(chunk_map_start_location)
|
|
raw_text = self._fh.read(-1)
|
|
return LabelMap(raw_text)
|
|
|
|
def _calculate_field_of_view(self, index):
|
|
"""Determines what field of view was being imaged for a given image.
|
|
|
|
Args:
|
|
index(int): the index (which is simply the order in which the image was acquired)
|
|
|
|
Returns:
|
|
int: the field of view
|
|
"""
|
|
images_per_cycle = len(self.metadata["z_levels"]) * len(self.metadata["channels"])
|
|
return int((index - (index % images_per_cycle)) / images_per_cycle) % len(self.metadata["fields_of_view"])
|
|
|
|
def _calculate_channel(self, index):
|
|
"""Determines what channel a particular image is.
|
|
|
|
Args:
|
|
index(int): the index (which is simply the order in which the image was acquired)
|
|
|
|
Returns:
|
|
string: the name of the color channel
|
|
|
|
"""
|
|
return self.metadata["channels"][index % len(self.metadata["channels"])]
|
|
|
|
def _calculate_z_level(self, index):
|
|
"""Determines the plane in the z-axis a given image was taken in.
|
|
|
|
In the future, this will be replaced with the actual offset in micrometers.
|
|
|
|
Args:
|
|
index(int): the index (which is simply the order in which the image was acquired)
|
|
|
|
Returns:
|
|
The z level
|
|
|
|
"""
|
|
return self.metadata["z_levels"][int(
|
|
((index - (index % len(self.metadata["channels"]))) / len(self.metadata["channels"])) % len(
|
|
self.metadata["z_levels"]))]
|
|
|
|
def _calculate_image_group_number(self, frame_number, fov, z_level):
|
|
"""
|
|
Images are grouped together if they share the same time index, field of view, and z-level.
|
|
|
|
Args:
|
|
frame_number: the time index
|
|
fov: the field of view number
|
|
z_level: the z level number
|
|
|
|
Returns:
|
|
int: the image group number
|
|
|
|
"""
|
|
return frame_number * len(self.metadata["fields_of_view"]) * len(self.metadata["z_levels"]) + (
|
|
fov * len(self.metadata["z_levels"]) + z_level)
|
|
|
|
def _calculate_frame_number(self, image_group_number, field_of_view, z_level):
|
|
"""
|
|
Images are in the same frame if they share the same group number and field of view and are taken sequentially.
|
|
|
|
Args:
|
|
image_group_number: the image group number (see _calculate_image_group_number)
|
|
field_of_view: the field of view number
|
|
z_level: the z level number
|
|
|
|
Returns:
|
|
|
|
"""
|
|
return (image_group_number - (field_of_view * len(self.metadata["z_levels"]) + z_level)) / (
|
|
len(self.metadata["fields_of_view"]) * len(self.metadata["z_levels"]))
|
|
|
|
@property
|
|
def _channel_offset(self):
|
|
"""
|
|
Image data is interleaved for each image set. That is, if there are four images in a set, the first image
|
|
will consist of pixels 1, 5, 9, etc, the second will be pixels 2, 6, 10, and so forth.
|
|
|
|
Returns:
|
|
dict: the channel offset for each channel
|
|
|
|
"""
|
|
return {channel: n for n, channel in enumerate(self.metadata["channels"])}
|
|
|
|
def _get_raw_image_data(self, image_group_number, channel_offset, height, width):
|
|
"""Reads the raw bytes and the timestamp of an image.
|
|
|
|
Args:
|
|
image_group_number: the image group number (see _calculate_image_group_number)
|
|
channel_offset: the number of the color channel
|
|
height: the height of the image
|
|
width: the width of the image
|
|
|
|
Returns:
|
|
|
|
"""
|
|
chunk = self._label_map.get_image_data_location(image_group_number)
|
|
data = read_chunk(self._fh, chunk)
|
|
|
|
# All images in the same image group share the same timestamp! So if you have complicated image data,
|
|
# your timestamps may not be entirely accurate. Practically speaking though, they'll only be off by a few
|
|
# seconds unless you're doing something super weird.
|
|
timestamp = struct.unpack("d", data[:8])[0]
|
|
image_group_data = array.array("H", data)
|
|
image_data_start = 4 + channel_offset
|
|
|
|
# The images for the various channels are interleaved within the same array. For example, the second image
|
|
# of a four image group will be composed of bytes 2, 6, 10, etc. If you understand why someone would design
|
|
# a data structure that way, please send the author of this library a message.
|
|
number_of_true_channels = int((len(image_group_data) - 4) / (height * width))
|
|
image_data = np.reshape(image_group_data[image_data_start::number_of_true_channels], (height, width))
|
|
|
|
# Skip images that are all zeros! This is important, since NIS Elements creates blank "gap" images if you
|
|
# don't have the same number of images each cycle. We discovered this because we only took GFP images every
|
|
# other cycle to reduce phototoxicity, but NIS Elements still allocated memory as if we were going to take
|
|
# them every cycle.
|
|
if np.any(image_data):
|
|
return timestamp, Frame(image_data, metadata=self._get_frame_metadata())
|
|
|
|
raise NoImageError
|
|
|
|
def _get_frame_metadata(self):
|
|
"""Get the metadata for one frame
|
|
|
|
Returns:
|
|
dict: a dictionary containing the parsed metadata
|
|
|
|
"""
|
|
return self.metadata
|