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optimize: improve typing of xref_exts

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This commit is contained in:
James R. Barlow
2020-07-07 22:41:29 -07:00
parent b20a6e4c5d
commit 373f27832b
1 changed files with 43 additions and 31 deletions
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src/ocrmypdf/optimize.py
+43 -31
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@@ -22,7 +22,19 @@ from collections import defaultdict
from functools import partial
from os import fspath
from pathlib import Path
from typing import Any, Callable, Dict, Iterator, List, Optional, Sequence, Tuple, Union
from typing import (
Any,
Callable,
Dict,
Iterator,
List,
MutableSet,
NamedTuple,
Optional,
Sequence,
Tuple,
Union,
)
import pikepdf
from pikepdf import Dictionary, Name, Object, Pdf, PdfImage
@@ -42,6 +54,11 @@ DEFAULT_JPEG_QUALITY = 75
DEFAULT_PNG_QUALITY = 70
class XrefExt(NamedTuple):
xref: int
ext: str
def img_name(root: Path, xref: int, ext: str) -> str:
return fspath(root / f'{xref:08d}{ext}')
@@ -60,7 +77,7 @@ def tif_name(root: Path, xref: int) -> str:
def extract_image_filter(
pike: Pdf, root: Path, image: Object, xref: int
) -> Optional[Tuple[PdfImage, Tuple[Name, Any]]]:
) -> Optional[Tuple[PdfImage, Tuple[Name, Object]]]:
if image.Subtype != Name.Image:
return None
if image.Length < 100:
@@ -88,7 +105,7 @@ def extract_image_filter(
def extract_image_jbig2(
*, pike: pikepdf.Pdf, root: Path, image: Object, xref: int, options
) -> Optional[Tuple[int, str]]:
) -> Optional[XrefExt]:
result = extract_image_filter(pike, root, image, xref)
if result is None:
return None
@@ -106,13 +123,13 @@ def extract_image_jbig2(
imgname.rename(imgname.with_suffix(ext))
except pikepdf.UnsupportedImageTypeError:
return None
return xref, ext
return XrefExt(xref, ext)
return None
def extract_image_generic(
*, pike: Pdf, root: Path, image: PdfImage, xref: int, options
) -> Optional[Tuple[int, str]]:
) -> Optional[XrefExt]:
result = extract_image_filter(pike, root, image, xref)
if result is None:
return None
@@ -151,7 +168,7 @@ def extract_image_generic(
imgname.rename(imgname.with_suffix(ext))
except pikepdf.UnsupportedImageTypeError:
return None
return xref, ext
return XrefExt(xref, ext)
elif (
pim.indexed
and pim.colorspace in pim.SIMPLE_COLORSPACES
@@ -160,12 +177,12 @@ def extract_image_generic(
# Try to improve on indexed images - these are far from low hanging
# fruit in most cases
pim.as_pil_image().save(png_name(root, xref))
return xref, '.png'
return XrefExt(xref, '.png')
elif not pim.indexed and pim.colorspace in pim.SIMPLE_COLORSPACES:
# An optimization opportunity here, not currently taken, is directly
# generating a PNG from compressed data
pim.as_pil_image().save(png_name(root, xref))
return xref, '.png'
return XrefExt(xref, '.png')
elif (
not pim.indexed
and pim.colorspace == Name.ICCBased
@@ -176,17 +193,14 @@ def extract_image_generic(
# paying any attention to the ICC profile, provided we're not doing
# lossy JBIG2
pim.as_pil_image().save(png_name(root, xref))
return xref, '.png'
return XrefExt(xref, '.png')
return None
def extract_images(
pike: Pdf,
root: Path,
options,
extract_fn: Callable[..., Optional[Tuple[int, str]]],
) -> Iterator[Tuple[int, int, str]]:
pike: Pdf, root: Path, options, extract_fn: Callable[..., Optional[XrefExt]],
) -> Iterator[Tuple[int, XrefExt]]:
"""Extract image using extract_fn
Enumerate images on each page, lookup their xref/ID number in the PDF.
@@ -236,7 +250,7 @@ def extract_images(
else:
if result:
_, ext = result
yield pageno_for_xref[xref], xref, ext
yield pageno_for_xref[xref], XrefExt(xref, ext)
def extract_images_generic(
@@ -246,25 +260,23 @@ def extract_images_generic(
jpegs = []
pngs = []
for _, xref, ext in extract_images(pike, root, options, extract_image_generic):
log.debug('xref = %s ext = %s', xref, ext)
if ext == '.png':
pngs.append(xref)
elif ext == '.jpg':
jpegs.append(xref)
for _, xref_ext in extract_images(pike, root, options, extract_image_generic):
log.debug('xref_ext = %s', xref_ext)
if xref_ext.ext == '.png':
pngs.append(xref_ext.xref)
elif xref_ext.ext == '.jpg':
jpegs.append(xref_ext.xref)
log.debug("Optimizable images: JPEGs: %s PNGs: %s", len(jpegs), len(pngs))
return jpegs, pngs
def extract_images_jbig2(
pike: Pdf, root: Path, options
) -> Dict[int, List[Tuple[int, str]]]:
def extract_images_jbig2(pike: Pdf, root: Path, options) -> Dict[int, List[XrefExt]]:
"""Extract any bitonal image that we think we can improve as JBIG2"""
jbig2_groups = defaultdict(list)
for pageno, xref, ext in extract_images(pike, root, options, extract_image_jbig2):
for pageno, xref_ext in extract_images(pike, root, options, extract_image_jbig2):
group = pageno // options.jbig2_page_group_size
jbig2_groups[group].append((xref, ext))
jbig2_groups[group].append(xref_ext)
# Elide empty groups
jbig2_groups = {
@@ -275,11 +287,11 @@ def extract_images_jbig2(
def _produce_jbig2_images(
jbig2_groups: Dict[int, List[Tuple[int, str]]], root: Path, options
jbig2_groups: Dict[int, List[XrefExt]], root: Path, options
) -> None:
"""Produce JBIG2 images from their groups"""
def jbig2_group_args(root: Path, groups: Dict[int, List[Tuple[int, str]]]):
def jbig2_group_args(root: Path, groups: Dict[int, List[XrefExt]]):
for group, xref_exts in groups.items():
prefix = f'group{group:08d}'
yield dict(
@@ -288,7 +300,7 @@ def _produce_jbig2_images(
out_prefix=prefix,
)
def jbig2_single_args(root, groups: Dict[int, List[Tuple[int, str]]]):
def jbig2_single_args(root, groups: Dict[int, List[XrefExt]]):
for group, xref_exts in groups.items():
prefix = f'group{group:08d}'
# Second loop is to ensure multiple images per page are unpacked
@@ -325,7 +337,7 @@ def _produce_jbig2_images(
def convert_to_jbig2(
pike: Pdf, jbig2_groups: Dict[int, List[Tuple[int, str]]], root: Path, options
pike: Pdf, jbig2_groups: Dict[int, List[XrefExt]], root: Path, options
) -> None:
"""Convert images to JBIG2 and insert into PDF.
@@ -394,7 +406,7 @@ def transcode_pngs(
root: Path,
options,
) -> None:
modified = set()
modified: MutableSet[int] = set()
if options.optimize >= 2:
png_quality = (
max(10, options.png_quality - 10),