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Pgm

PGMLoader

Bases: KoshLoader

Source code in kosh/loaders/pgm.py 
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class PGMLoader(KoshLoader):
    types = {"pgm": ["numpy", ]}

    def __init__(self, obj, **kargs):
        """PGMLoader for Kosh to be able to read in pgm image files
        :param obj: Kosh obj reference
        """
        super(PGMLoader, self).__init__(obj, **kargs)

    def open(self, mode="rb"):
        """open the pgm reader
        :param mode: mode to open the file in, defaults to 'r'
        :type mode: str, optional
        :return: Image file
        :rtype: file
        """
        return open(self.uri, mode)

    def extract(self):
        """get a feature

        :return: numpy array
        :rtype: numpy.ndarray
        """
        import numpy
        with open(self.uri, "rb") as f:
            magic = f.read(2).decode()
            if magic == 'P2':  # ASCII encoded
                _ = f.read(2)
                _ = read_chunk(f)
                dims = read_chunk(f)
                w, h = [int(x) for x in dims.split()]
                max_value = int(read_chunk(f))
                n = w*h
                data = numpy.array([int(x) for x in f.read().decode().split()]).reshape(h, w)
            elif magic == 'P5':  # binary encoded
                _ = f.read(1)
                dims = read_chunk(f)
                w, h = [int(x) for x in dims.split()]
                max_value = int(read_chunk(f))
                n = w*h
                data = numpy.frombuffer(
                    f.read(), dtype='u1' if max_value < 256 else 'u2', count=n).reshape(h, w)
            else:
                raise ValueError("Cannot read pgm magic number {magic}".format(magic=magic))

        return data

    def list_features(self):
        """list_features lists features available

        :return: list of features you can retrievea ["iamge", ] in our case
        :rtype: list
        """

        return ["image", ]

    def describe_feature(self, feature):
        """describe_feature describe the feature as a dictionary

        :param feature: feature to describe
        :type feature: str
        :return: dictionary with attributes describing the feature: 'size', 'format', 'max_value'
        :rtype: dict
        """
        with open(self.uri, "rb") as f:
            magic = f.read(2).decode()
            if magic == 'P2':  # ASCII encoded
                _ = f.read(2)
                _ = read_chunk(f)
                dims = read_chunk(f)
                w, h = [int(x) for x in dims.split()]
                max_value = int(read_chunk(f))
            elif magic == 'P5':  # binary encoded
                _ = f.read(1)
                dims = read_chunk(f)
                w, h = [int(x) for x in dims.split()]
                max_value = int(read_chunk(f))
            else:
                raise ValueError("Cannot read pgm magic number {magic}".format(magic=magic))

        return {"size": (h, w), "format": "pgm ({magic})".format(magic=magic), "max_value": max_value}

__init__(obj, **kargs)

PGMLoader for Kosh to be able to read in pgm image files

Parameters:

Name Type Description Default
obj

Kosh obj reference

 required
Source code in kosh/loaders/pgm.py 
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def __init__(self, obj, **kargs):
    """PGMLoader for Kosh to be able to read in pgm image files
    :param obj: Kosh obj reference
    """
    super(PGMLoader, self).__init__(obj, **kargs)

describe_feature(feature)

describe_feature describe the feature as a dictionary

Parameters:

Name Type Description Default
feature str

feature to describe

 required

Returns:

Type Description
dict

dictionary with attributes describing the feature: 'size', 'format', 'max_value'
Source code in kosh/loaders/pgm.py 
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def describe_feature(self, feature):
    """describe_feature describe the feature as a dictionary

    :param feature: feature to describe
    :type feature: str
    :return: dictionary with attributes describing the feature: 'size', 'format', 'max_value'
    :rtype: dict
    """
    with open(self.uri, "rb") as f:
        magic = f.read(2).decode()
        if magic == 'P2':  # ASCII encoded
            _ = f.read(2)
            _ = read_chunk(f)
            dims = read_chunk(f)
            w, h = [int(x) for x in dims.split()]
            max_value = int(read_chunk(f))
        elif magic == 'P5':  # binary encoded
            _ = f.read(1)
            dims = read_chunk(f)
            w, h = [int(x) for x in dims.split()]
            max_value = int(read_chunk(f))
        else:
            raise ValueError("Cannot read pgm magic number {magic}".format(magic=magic))

    return {"size": (h, w), "format": "pgm ({magic})".format(magic=magic), "max_value": max_value}

extract()

get a feature

Returns:

Type Description
numpy.ndarray

numpy array
Source code in kosh/loaders/pgm.py 
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def extract(self):
    """get a feature

    :return: numpy array
    :rtype: numpy.ndarray
    """
    import numpy
    with open(self.uri, "rb") as f:
        magic = f.read(2).decode()
        if magic == 'P2':  # ASCII encoded
            _ = f.read(2)
            _ = read_chunk(f)
            dims = read_chunk(f)
            w, h = [int(x) for x in dims.split()]
            max_value = int(read_chunk(f))
            n = w*h
            data = numpy.array([int(x) for x in f.read().decode().split()]).reshape(h, w)
        elif magic == 'P5':  # binary encoded
            _ = f.read(1)
            dims = read_chunk(f)
            w, h = [int(x) for x in dims.split()]
            max_value = int(read_chunk(f))
            n = w*h
            data = numpy.frombuffer(
                f.read(), dtype='u1' if max_value < 256 else 'u2', count=n).reshape(h, w)
        else:
            raise ValueError("Cannot read pgm magic number {magic}".format(magic=magic))

    return data

list_features()

list_features lists features available

Returns:

Type Description
list

list of features you can retrievea ["iamge", ] in our case
Source code in kosh/loaders/pgm.py 
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def list_features(self):
    """list_features lists features available

    :return: list of features you can retrievea ["iamge", ] in our case
    :rtype: list
    """

    return ["image", ]

open(mode='rb')

open the pgm reader

Parameters:

Name Type Description Default
mode (str, optional)

mode to open the file in, defaults to 'r'

 'rb'

Returns:

Type Description
file

Image file
Source code in kosh/loaders/pgm.py 
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def open(self, mode="rb"):
    """open the pgm reader
    :param mode: mode to open the file in, defaults to 'r'
    :type mode: str, optional
    :return: Image file
    :rtype: file
    """
    return open(self.uri, mode)