278 lines
8.2 KiB
Python
278 lines
8.2 KiB
Python
import atexit
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from _operator import itemgetter
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from functools import partial, lru_cache
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from itertools import chain, filterfalse
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from operator import itemgetter
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from typing import List, Union
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import fitz
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import numpy as np
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from PIL import Image
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from funcy import merge, compose, rcompose, keep
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from pymonad.either import Right, Left, Either
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from pymonad.tools import curry, identity
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from image_prediction.exceptions import InvalidBox, BadXref
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from image_prediction.formatter.formatters.enum import EnumFormatter
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from image_prediction.image_extractor.extractor import ImageExtractor, ImageMetadataPair
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from image_prediction.info import Info
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from image_prediction.stitching.stitching import stitch_pairs
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from image_prediction.stitching.utils import validate_box
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from image_prediction.utils import get_logger
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from image_prediction.utils.generic import bottom, left, right
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logger = get_logger()
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class ParsablePDFImageExtractor(ImageExtractor):
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def __init__(self, verbose=False, tolerance=0):
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"""
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Args:
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verbose: Whether to show progressbar
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tolerance: The tolerance in pixels for the distance between images, beyond which they will not be stitched
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together
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"""
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self.doc: Union[fitz.fitz.Document, None] = None
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self.verbose = verbose
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self.tolerance = tolerance
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def extract(self, pdf: bytes, page_range: range = None):
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self.doc = fitz.Document(stream=pdf)
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pages = extract_pages(self.doc, page_range) if page_range else self.doc
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image_metadata_pairs = chain.from_iterable(map(self.__process_images_on_page, pages))
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yield from image_metadata_pairs
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def __process_images_on_page(self, page: fitz.fitz.Page):
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metadata = extract_valid_metadata(self.doc, page)
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maybe_image_metadata_pairs = map(partial(metadatum_to_image_metadata_pair, self.doc), metadata)
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image_metadata_pairs = keep(take_right, maybe_image_metadata_pairs)
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clear_caches()
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image_metadata_pairs = stitch_pairs(list(image_metadata_pairs), tolerance=self.tolerance)
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yield from image_metadata_pairs
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def take_right(pair: Either):
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if pair.is_right():
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return pair.either(bottom, identity)
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logger.warning(f"Skipping bad image. {pair.either(format_context, bottom)}")
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def format_context(context):
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return f"Reason: {context['reason'].rstrip('.')}. Metadata: {EnumFormatter()(context['metadata'])}"
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def extract_pages(doc, page_range):
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page_range = range(page_range.start + 1, page_range.stop + 1)
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pages = map(doc.load_page, page_range)
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yield from pages
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def validate_image(image: Image.Image) -> Either:
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try:
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# TODO: stand-in heuristic for testing if image is valid => find cleaner solution (RED-5148)
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image.resize((100, 100)).convert("RGB")
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return Right(image)
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except (OSError, Exception):
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logger.warning(f"Invalid image encountered.")
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return Left("Invalid image.")
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def extract_valid_metadata(doc: fitz.fitz.Document, page: fitz.fitz.Page):
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return compose(
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list,
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partial(add_alpha_channel_info, doc),
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filter_valid_metadata,
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get_metadata_for_images_on_page,
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)(page)
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def metadatum_to_image_metadata_pair(doc, metadatum: dict) -> Either:
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maybe_image = xref_to_maybe_image(doc, metadatum[Info.XREF]).bind(validate_image)
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maybe_image_metadata_pair = make_maybe_image_metadata_pair(maybe_image, Right(metadatum))
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return maybe_image_metadata_pair
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def add_alpha_channel_info(doc, metadata):
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def add_alpha_value_to_metadatum(metadatum):
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alpha = metadatum_to_alpha_value(metadatum)
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return {**metadatum, Info.ALPHA: alpha}
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xref_to_alpha = partial(has_alpha_channel, doc)
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metadatum_to_alpha_value = compose(xref_to_alpha, itemgetter(Info.XREF))
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yield from map(add_alpha_value_to_metadatum, metadata)
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def filter_valid_metadata(metadata):
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yield from compose(filter_out_tiny_images, filter_out_invalid_metadata)(metadata)
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def get_metadata_for_images_on_page(page: fitz.Page):
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metadata = map(get_image_metadata, get_image_infos(page))
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metadata = add_page_metadata(page, metadata)
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yield from metadata
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@lru_cache(maxsize=None)
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def xref_to_maybe_image(doc, xref) -> Either:
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try:
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return Right(extract_image(doc, xref))
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except BadXref:
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return Left("Bad xref.")
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def make_maybe_image_metadata_pair(image: Either, metadata: Either):
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"""Reference: haskell.org/tutorial/monads.html"""
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def context(value):
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return {"reason": value, "metadata": metadata.either(bottom, identity)}
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# What is most readable?
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# 1)
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# return Either.apply(make_image_metadata_pair).to_arguments(image, metadata).either(left(context), right(identity))
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# 2)
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# m (a -> b -> c) -> m a -> m b -> m c
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# return Right(make_image_metadata_pair).amap(image).amap(metadata).either(left(context), right(identity))
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# 3)
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return (
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image.bind(right(make_image_metadata_pair)) # m a >>= m (a -> b -> c) -> m (b -> c)
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.amap(metadata) # m (b -> c) <*> m b -> m c
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.either(
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left(context),
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right(identity),
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)
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)
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@curry(2)
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def make_image_metadata_pair(image: Image.Image, metadatum: dict) -> ImageMetadataPair:
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return ImageMetadataPair(image, metadatum)
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def extract_image(doc, xref) -> Image.Image:
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try:
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pixmap = fitz.Pixmap(doc, xref)
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except ValueError as err:
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msg = f"Xref {xref} is invalid, skipping extraction."
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logger.debug(msg)
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raise BadXref(msg) from err
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array = np.frombuffer(pixmap.samples, dtype=np.uint8).reshape((pixmap.h, pixmap.w, pixmap.n))
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array = normalize_channels(array)
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return Image.fromarray(array)
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def has_alpha_channel(doc, xref):
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maybe_image = load_image_handle_from_xref(doc, xref)
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maybe_smask = maybe_image["smask"] if maybe_image else None
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if maybe_smask:
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return any([doc.extract_image(maybe_smask) is not None, bool(fitz.Pixmap(doc, maybe_smask).alpha)])
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else:
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try:
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return bool(fitz.Pixmap(doc, xref).alpha)
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except ValueError:
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logger.debug(f"Encountered invalid xref `{xref}` in {doc.metadata.get('title', '<no title>')}.")
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return False
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def filter_out_tiny_images(metadata):
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yield from filterfalse(tiny, metadata)
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def filter_out_invalid_metadata(metadata):
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def __validate_box(box):
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try:
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return validate_box(box)
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except InvalidBox as err:
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logger.debug(f"Dropping invalid metadatum, reason: {err}")
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yield from keep(__validate_box, metadata)
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def get_image_metadata(image_info):
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xref, coords = itemgetter("xref", "bbox")(image_info)
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x1, y1, x2, y2 = map(rounder, coords)
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width = abs(x2 - x1)
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height = abs(y2 - y1)
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return {
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Info.WIDTH: width,
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Info.HEIGHT: height,
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Info.X1: x1,
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Info.X2: x2,
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Info.Y1: y1,
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Info.Y2: y2,
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Info.XREF: xref,
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}
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@lru_cache(maxsize=None)
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def get_image_infos(page: fitz.Page) -> List[dict]:
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return page.get_image_info(xrefs=True)
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def add_page_metadata(page, metadata):
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yield from map(partial(merge, get_page_metadata(page)), metadata)
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def normalize_channels(array: np.ndarray):
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if not array.ndim == 3:
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array = np.expand_dims(array, axis=-1)
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if array.shape[-1] == 4:
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array = array[..., :3]
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elif array.shape[-1] == 1:
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array = np.concatenate([array, array, array], axis=-1)
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elif array.shape[-1] != 3:
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logger.warning(f"Unexpected image format: {array.shape}.")
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raise ValueError(f"Unexpected image format: {array.shape}.")
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return array
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@lru_cache(maxsize=None)
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def load_image_handle_from_xref(doc, xref):
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return doc.extract_image(xref)
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def get_page_metadata(page):
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page_width, page_height = map(rounder, page.mediabox_size)
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return {
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Info.PAGE_WIDTH: page_width,
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Info.PAGE_HEIGHT: page_height,
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Info.PAGE_IDX: page.number,
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}
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rounder = rcompose(round, int)
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def tiny(metadatum):
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return metadatum[Info.WIDTH] * metadatum[Info.HEIGHT] <= 4
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def clear_caches():
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get_image_infos.cache_clear()
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load_image_handle_from_xref.cache_clear()
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xref_to_maybe_image.cache_clear()
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atexit.register(clear_caches)
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