294 lines
9.3 KiB
Python
294 lines
9.3 KiB
Python
import os
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import os.path
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import struct
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from io import BytesIO
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from typing import BinaryIO, Literal
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from pdfminer.jbig2 import JBIG2StreamReader, JBIG2StreamWriter
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from pdfminer.layout import LTImage
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from pdfminer.pdfcolor import (
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LITERAL_DEVICE_CMYK,
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LITERAL_DEVICE_GRAY,
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LITERAL_DEVICE_RGB,
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LITERAL_INLINE_DEVICE_GRAY,
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LITERAL_INLINE_DEVICE_RGB,
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)
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from pdfminer.pdfexceptions import PDFValueError
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from pdfminer.pdftypes import (
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LITERALS_DCT_DECODE,
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LITERALS_FLATE_DECODE,
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LITERALS_JBIG2_DECODE,
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LITERALS_JPX_DECODE,
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)
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PIL_ERROR_MESSAGE = (
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"Could not import Pillow. This dependency of pdfminer.six is not "
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"installed by default. You need it to to save jpg images to a file. Install it "
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"with `pip install 'pdfminer.six[image]'`"
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)
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def align32(x: int) -> int:
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return ((x + 3) // 4) * 4
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class BMPWriter:
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def __init__(self, fp: BinaryIO, bits: int, width: int, height: int) -> None:
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self.fp = fp
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self.bits = bits
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self.width = width
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self.height = height
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if bits == 1:
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ncols = 2
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elif bits == 8:
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ncols = 256
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elif bits == 24:
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ncols = 0
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else:
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raise PDFValueError(bits)
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self.linesize = align32((self.width * self.bits + 7) // 8)
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self.datasize = self.linesize * self.height
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headersize = 14 + 40 + ncols * 4
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info = struct.pack(
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"<IiiHHIIIIII",
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40,
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self.width,
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self.height,
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1,
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self.bits,
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0,
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self.datasize,
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0,
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0,
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ncols,
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0,
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)
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assert len(info) == 40, str(len(info))
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header = struct.pack(
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"<ccIHHI",
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b"B",
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b"M",
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headersize + self.datasize,
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0,
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0,
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headersize,
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)
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assert len(header) == 14, str(len(header))
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self.fp.write(header)
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self.fp.write(info)
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if ncols == 2:
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# B&W color table
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for i in (0, 255):
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self.fp.write(struct.pack("BBBx", i, i, i))
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elif ncols == 256:
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# grayscale color table
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for i in range(256):
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self.fp.write(struct.pack("BBBx", i, i, i))
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self.pos0 = self.fp.tell()
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self.pos1 = self.pos0 + self.datasize
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def write_line(self, y: int, data: bytes) -> None:
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self.fp.seek(self.pos1 - (y + 1) * self.linesize)
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self.fp.write(data)
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class ImageWriter:
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"""Write image to a file
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Supports various image types: JPEG, JBIG2 and bitmaps
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"""
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def __init__(self, outdir: str) -> None:
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self.outdir = outdir
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if not os.path.exists(self.outdir):
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os.makedirs(self.outdir)
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def export_image(self, image: LTImage) -> str:
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"""Save an LTImage to disk"""
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(width, height) = image.srcsize
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filters = image.stream.get_filters()
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if not filters:
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name = self._save_bytes(image)
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elif filters[-1][0] in LITERALS_DCT_DECODE:
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name = self._save_jpeg(image)
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elif filters[-1][0] in LITERALS_JPX_DECODE:
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name = self._save_jpeg2000(image)
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elif self._is_jbig2_iamge(image):
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name = self._save_jbig2(image)
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elif image.bits == 1:
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name = self._save_bmp(image, width, height, (width + 7) // 8, image.bits)
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elif image.bits == 8 and (
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LITERAL_DEVICE_RGB in image.colorspace
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or LITERAL_INLINE_DEVICE_RGB in image.colorspace
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):
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name = self._save_bmp(image, width, height, width * 3, image.bits * 3)
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elif image.bits == 8 and (
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LITERAL_DEVICE_GRAY in image.colorspace
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or LITERAL_INLINE_DEVICE_GRAY in image.colorspace
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):
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name = self._save_bmp(image, width, height, width, image.bits)
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elif len(filters) == 1 and filters[0][0] in LITERALS_FLATE_DECODE:
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name = self._save_bytes(image)
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else:
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name = self._save_raw(image)
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return name
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def _save_jpeg(self, image: LTImage) -> str:
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"""Save a JPEG encoded image"""
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data = image.stream.get_data()
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name, path = self._create_unique_image_name(image, ".jpg")
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with open(path, "wb") as fp:
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if LITERAL_DEVICE_CMYK in image.colorspace:
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try:
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from PIL import Image, ImageChops # type: ignore[import]
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except ImportError as err:
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raise ImportError(PIL_ERROR_MESSAGE) from err
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ifp = BytesIO(data)
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img = Image.open(ifp)
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inverted = ImageChops.invert(img)
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rgb_img = inverted.convert("RGB")
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rgb_img.save(fp, "JPEG")
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else:
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fp.write(data)
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return name
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def _save_jpeg2000(self, image: LTImage) -> str:
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"""Save a JPEG 2000 encoded image"""
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data = image.stream.get_data()
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name, path = self._create_unique_image_name(image, ".jp2")
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with open(path, "wb") as fp:
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try:
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from PIL import Image # type: ignore[import]
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except ImportError as err:
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raise ImportError(PIL_ERROR_MESSAGE) from err
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# if we just write the raw data, most image programs
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# that I have tried cannot open the file. However,
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# open and saving with PIL produces a file that
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# seems to be easily opened by other programs
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ifp = BytesIO(data)
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i = Image.open(ifp)
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i.save(fp, "JPEG2000")
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return name
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def _save_jbig2(self, image: LTImage) -> str:
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"""Save a JBIG2 encoded image"""
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name, path = self._create_unique_image_name(image, ".jb2")
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with open(path, "wb") as fp:
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input_stream = BytesIO()
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global_streams = []
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filters = image.stream.get_filters()
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for filter_name, params in filters:
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if filter_name in LITERALS_JBIG2_DECODE:
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global_streams.append(params["JBIG2Globals"].resolve())
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if len(global_streams) > 1:
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msg = (
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"There should never be more than one JBIG2Globals "
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"associated with a JBIG2 embedded image"
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)
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raise PDFValueError(msg)
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if len(global_streams) == 1:
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input_stream.write(global_streams[0].get_data().rstrip(b"\n"))
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input_stream.write(image.stream.get_data())
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input_stream.seek(0)
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reader = JBIG2StreamReader(input_stream)
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segments = reader.get_segments()
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writer = JBIG2StreamWriter(fp)
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writer.write_file(segments)
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return name
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def _save_bmp(
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self,
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image: LTImage,
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width: int,
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height: int,
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bytes_per_line: int,
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bits: int,
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) -> str:
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"""Save a BMP encoded image"""
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name, path = self._create_unique_image_name(image, ".bmp")
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with open(path, "wb") as fp:
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bmp = BMPWriter(fp, bits, width, height)
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data = image.stream.get_data()
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i = 0
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for y in range(height):
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bmp.write_line(y, data[i : i + bytes_per_line])
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i += bytes_per_line
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return name
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def _save_bytes(self, image: LTImage) -> str:
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"""Save an image without encoding, just bytes"""
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name, path = self._create_unique_image_name(image, ".jpg")
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width, height = image.srcsize
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channels = len(image.stream.get_data()) / width / height / (image.bits / 8)
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with open(path, "wb") as fp:
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try:
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from PIL import (
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Image, # type: ignore[import]
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ImageOps,
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)
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except ImportError as err:
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raise ImportError(PIL_ERROR_MESSAGE) from err
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mode: Literal["1", "L", "RGB", "CMYK"]
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if image.bits == 1:
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mode = "1"
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elif image.bits == 8 and channels == 1:
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mode = "L"
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elif image.bits == 8 and channels == 3:
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mode = "RGB"
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elif image.bits == 8 and channels == 4:
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mode = "CMYK"
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img = Image.frombytes(mode, image.srcsize, image.stream.get_data(), "raw")
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if mode == "L":
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img = ImageOps.invert(img)
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img.save(fp)
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return name
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def _save_raw(self, image: LTImage) -> str:
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"""Save an image with unknown encoding"""
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ext = f".{image.bits}.{image.srcsize[0]}x{image.srcsize[1]}.img"
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name, path = self._create_unique_image_name(image, ext)
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with open(path, "wb") as fp:
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fp.write(image.stream.get_data())
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return name
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@staticmethod
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def _is_jbig2_iamge(image: LTImage) -> bool:
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filters = image.stream.get_filters()
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for filter_name, _params in filters:
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if filter_name in LITERALS_JBIG2_DECODE:
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return True
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return False
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def _create_unique_image_name(self, image: LTImage, ext: str) -> tuple[str, str]:
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name = image.name + ext
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path = os.path.join(self.outdir, name)
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img_index = 0
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while os.path.exists(path):
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name = f"{image.name}.{img_index}{ext}"
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path = os.path.join(self.outdir, name)
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img_index += 1
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return name, path
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