'Create instance from image metadata dict
:param image_meta: image metadata dictionary
Creates a new object instance, initializing from the
properties associated with the image metadata instance
:returns: an ImageMeta instance'

@classmethod
def from_dict(cls, image_meta):

    if (image_meta is None):
        image_meta = {}
    image_meta = copy.deepcopy(image_meta)
    image_meta['properties'] = objects.ImageMetaProps.from_dict(image_meta.get('properties', {}))
    for fld in NULLABLE_STRING_FIELDS:
        if ((fld in image_meta) and (image_meta[fld] is None)):
            image_meta[fld] = ''
    for fld in NULLABLE_INTEGER_FIELDS:
        if ((fld in image_meta) and (image_meta[fld] is None)):
            image_meta[fld] = 0
    return cls(**image_meta)
