def build_dict(img_iterator):
    """
    Build a dict from files from iterator.
    {'absolute_filename': {'EXIF field': 'exif tag value'}}
    Parse DateTime from filename in the same loop, added as 'TIME'.
    """
    files_with_tags = dict()
    for f in img_iterator:
        with open(str(f.abspath()), 'rb') as jpg:
            tags = exifread.process_file(jpg)
            # Dont waste space on thumbnails
            try:
                del tags['JPEGThumbnail']
            except KeyError:
                pass
            tags['TIME'] = get_time(str(f.abspath()), tags)
            files_with_tags[str(f.abspath())] = tags
    return files_with_tags