使用 Python 压缩 PDF 的图像（帮助替换 PDF 中的图像）
Compressing a PDF's images using Python (help replacing images inside a PDF)
我的目标是拥有一个 Python 脚本，它将获取 PDF，提取其图像，compress/resize 它们，然后将此新数据推送到 PDF，这将产生一个新的，更小的 PDF。
到目前为止，除了用正确的对应物替换图像数据外，我已经完成了所有工作。我找到了图像数据所在的正确位置（在“stream”和“streamend”标签之间）。
这是我的代码（已更新）：
def crunchPdfImages(file_to_crunch, max_width=1200, max_height=628):
page_ratio = max_width / max_height
working_folder = os.path.dirname(file_to_crunch)
working_dir = os.path.join(working_folder, "temp_working_dir")
if not (os.path.exists(working_dir)): os.mkdir(working_dir)
# Get all the image...
extractPDFImages(file_to_crunch, working_dir)
# Compress all the images... (no resize)
all_image_list = [entry.path for entry in os.scandir(working_dir) if isImage(entry.path)]
for an_image in all_image_list:
img_picture = Image.open(an_image).convert("RGB")
img_picture.save(an_image, "JPEG", optimize=True)
# Uncompress the PDF
pdf_folder = os.path.join(working_dir, "pdf_uncompressed")
if not (os.path.exists(pdf_folder)): os.mkdir(pdf_folder)
pdf_datain_file = os.path.join(pdf_folder, "uncompressed_pdf.pdf")
pdf_dataout_file = os.path.join(pdf_folder, "new_images_pdf.pdf")
pypdftk.uncompress('"' + file_to_crunch + '"', pdf_datain_file)
# Now get to work...
# The PDF is comprised of objects, some of which are lablled as images.
# Each image has the line "/Subtype /Image" before the "stream" which is then ended by "endstream" then "endobj".
# In between the stream and endstream is the encoded image data... hopefully I can replace this in the same order that
# the images were taken out.
picture_replace_count = 0
pdf_openfile_in = open(pdf_datain_file, "rb")
pdf_openfile_out = open(pdf_dataout_file, "wb")
pdf_file_lines = pdf_openfile_in.readlines()
looking_for_next_stream = False
found_stream_and_removing = False
updating_xref_stage = 0
skip_a_line = False
for line in pdf_file_lines:
new_line_addition = "" # For adding to byte count, resetting to null here just in case
current_line_val = line.decode("Latin-1").strip()
if (looking_for_next_stream):
# Last image tag has been found but not dealt with, so find the stream then
if (current_line_val[:8] == "/Length "):
# Update the length
skip_a_line = True
new_img_size = str(os.path.getsize(all_image_list[picture_replace_count]))
new_line = r"/Length " + new_img_size + "\n"
pdf_openfile_out.write(new_line.encode("latin-1")) # add new line
if (current_line_val == "stream"):
print("Stream start found... skipping stream information")
looking_for_next_stream = False # it's been found
found_stream_and_removing = True # time to delete
new_line_addition = "stream\n".encode("latin-1")
pdf_openfile_out.write(new_line_addition) # add the line in or it will be skipped
elif (found_stream_and_removing):
if (current_line_val == "endstream"):
print("Stream end found")
found_stream_and_removing = False # Passed through all image data line
# Now, add in the new image data and continue on.
print("Adding new image data...")
#new_image_file = open(all_image_list[picture_replace_count], "rb")
img = Image.open(all_image_list[picture_replace_count], mode='r')
img_byte_arr = io.BytesIO()
img.save(img_byte_arr, format='JPEG')
img_byte_arr = img_byte_arr.getvalue()
pdf_openfile_out.write(img_byte_arr)
new_line_addition = img_byte_arr
"""
for imgline in new_image_file.readlines():
#pdf_openfile_out.write(imgline.encode("Latin-1"))
#pdf_openfile_out.write(imgline)
pass
#pdf_openfile_out.write("[IMAGEADD]".encode("latin-1")) # add new line
"""
#new_image_file.close()
picture_replace_count += 1
print("New image added.")
pdf_openfile_out.write("\n".encode("latin-1")) # add new line
if (picture_replace_count >= len(all_image_list)):
updating_xref_stage = 1 # All images replaced, now edit the xref.
elif (current_line_val == r"/Subtype /Image"):
print("Found an image place, number " + str(picture_replace_count))
print("Looking for stream start...")
looking_for_next_stream = True
# Find next
if not (found_stream_and_removing) and not (skip_a_line) and not (updating_xref_stage == 4):
pdf_openfile_out.write(line)
skip_a_line = False
pdf_openfile_in.close()
pdf_openfile_out.close()
print("Rebuilding xref table (post newfile creation)")
rebuildXrefTable(pdf_dataout_file)
并重建外部参照 table（根据此处的评论）我 运行 以下函数。我确实尝试在之前的函数中执行此操作，但数据最终以不同的大小输出。我还没有想出如何准确地将照片日期推送到 PDF 流中。
def rebuildXrefTable(pdf_file_in, pdf_file_out=None):
# Updating the xref table:
# * Assumes uncompressed PDF file
# To do this I need the number of bytes that precede and object (this is used as a reference).
# So, each line I will need to count the byte number and tally up
# When an object is found, the byte_count will be added to the reference list and then used to create the xref table
# Also need to update the "startxref" at the bottom (similar principle).
if (pdf_file_out == None): pdf_file_out = os.path.join(os.path.dirname(pdf_file_in), "rebuilt_xref_pdf.pdf")
print("Updating xref table of: " + os.path.basename(pdf_file_in))
byte_count = 0
xref_start = 0
object_location_reference = []
updating_xref_stage = 1
pdf_openfile_in = open(pdf_file_in, "rb")
pdf_openfile_out = open(pdf_file_out, "wb")
pdf_file_lines = pdf_openfile_in.readlines()
for line in pdf_file_lines:
current_line_val = line.decode("Latin-1").strip()
if (" obj" in current_line_val):
# Check if the place is an object loc, store byte reference and object index
obj_ref_index = current_line_val.split(" ")[0]
print("Found new object (index, location): (" + str(obj_ref_index) + ", " + str(byte_count) + ")")
object_location_reference.append((int(obj_ref_index), byte_count))
elif ("startxref" in current_line_val):
# This is the last thing to edit (right at the bottom, update the xref start location and then add the file end.
print("Updating the xref start value with new data...")
new_line = "startxref\n" + str(xref_start) + "\n" + r"%%EOF"
pdf_openfile_out.write(new_line.encode("latin-1"))
break
elif ("xref" in current_line_val):
print("Recording the new xref byte location")
preceeding_str = current_line_val.split("xref")[0]
preceeding_count = len(preceeding_str.encode("latin-1"))
xref_start = byte_count + preceeding_count # used at the end
updating_xref_stage = 2
elif (updating_xref_stage == 2 or updating_xref_stage == 3):
# This stage simply skips the first 2 xref data lines (and prints it o the new file as is)
updating_xref_stage += 1
elif (updating_xref_stage == 4):
print("Creating new xref object byte location table...")
object_location_reference.sort() # Sort the collected xref locations by their object index.
# Now add the new xref data information
for xref_loc in object_location_reference:
new_val = str(xref_loc[1]).zfill(10) # Pad the number out
new_val = new_val + " 00000 n \n"
pdf_openfile_out.write(new_val.encode("latin-1"))
updating_xref_stage = 5
elif (updating_xref_stage == 5):
# Stage 5 doesn't record the read in lines into new file
if ("trailer" in current_line_val): updating_xref_stage = 5
# Write to file
if not (updating_xref_stage == 5):
pdf_openfile_out.write(line)
byte_count += len(line)
pdf_openfile_in.close()
pdf_openfile_out.close()
外部参照 table 是准确的并且指向正确的字节位置，我还确保它的顺序正确（使用对象索引号，而不是它在文件中出现的顺序--这与原始 PDF 文档匹配）。
如果我不尝试替换任何东西而只是将数据输出到新的 PDF 文件中，它就可以工作并且我可以打开新文件。但是，当插入替换的JPG数据时，PDF无法打开，因为它已损坏。
我不知道如何将压缩图像中的正确数据推送到 PDF 文件。
我也试过像这样简单地推送JPG数据：
image = open(all_image_list[picture_replace_count], 'rb')
pdf_openfile_out.write(image.read())
image.close()
使用：Python 3.8
感谢这里的评论，我已经解决了这个问题。必须重建外部参照 table，并将 JPG 数据作为一个整体放置。这是工作代码：
def crunchPdfImages(file_to_crunch):
working_folder = os.path.dirname(file_to_crunch)
working_dir = os.path.join(working_folder, "temp_working_dir")
if not (os.path.exists(working_dir)): os.mkdir(working_dir)
# Get all the image...
extractPDFImages(file_to_crunch, working_dir)
# Compress all the images... (no resize, just optimise)
all_image_list = [entry.path for entry in os.scandir(working_dir) if isImage(entry.path)]
if (len(all_image_list) > 0):
for an_image in all_image_list:
img_picture = Image.open(an_image).convert("RGB")
img_picture.save(an_image, "JPEG", optimize=True)
else:
print("No images found in PDF...")
# Uncompress the PDF
pdf_folder = os.path.join(working_dir, "pdf_uncompressed")
if not (os.path.exists(pdf_folder)): os.mkdir(pdf_folder)
pdf_datain_file = os.path.join(pdf_folder, "uncompressed_pdf.pdf")
pdf_dataout_file = os.path.join(pdf_folder, "new_images_pdf.pdf")
print("Uncompressing PDF...")
pypdftk.uncompress('"' + file_to_crunch + '"', '"' + pdf_datain_file + '"')
# Now get to work...
# The PDF is comprised of objects, some of which are lablled as images.
# Each image has the line "/Subtype /Image" before the "stream" which is then ended by "endstream" then "endobj".
# In between the stream and endstream is the encoded image data... hopefully I can replace this in the same order that
# the images were taken out.
picture_replace_count = 0
pdf_openfile_in = open(pdf_datain_file, "rb")
pdf_openfile_out = open(pdf_dataout_file, "wb")
pdf_file_lines = pdf_openfile_in.readlines()
looking_for_next_stream = False
found_stream_and_removing = False
skip_a_line = False
for line in pdf_file_lines:
new_line_addition = "" # For adding to byte count, resetting to null here just in case
current_line_val = line.decode("Latin-1").strip()
if (looking_for_next_stream):
# Last image tag has been found but not dealt with, so find the stream then
if (current_line_val[:8] == "/Length "):
# Update the length
skip_a_line = True
new_img_size = str(os.path.getsize(all_image_list[picture_replace_count]))
new_line = r"/Length " + new_img_size + "\n"
pdf_openfile_out.write(new_line.encode("latin-1")) # add new line
if (current_line_val == "stream"):
print("Stream start found... skipping stream information")
looking_for_next_stream = False # it's been found
found_stream_and_removing = True # time to delete
new_line_addition = "stream\n".encode("latin-1")
pdf_openfile_out.write(new_line_addition) # add the line in or it will be skipped
elif (found_stream_and_removing):
if (current_line_val == "endstream"):
print("Stream end found")
found_stream_and_removing = False # Passed through all image data line
# Now, add in the new image data and continue on.
print("Adding new image data...")
image = open(all_image_list[picture_replace_count], 'rb')
pdf_openfile_out.write(image.read())
image.close()
picture_replace_count += 1
pdf_openfile_out.write("\n".encode("latin-1")) # add new line
elif (current_line_val == r"/Subtype /Image"):
print("Found an image place, number " + str(picture_replace_count))
print("Looking for stream start...")
looking_for_next_stream = True
# Find next
if not (found_stream_and_removing) and not (skip_a_line):
pdf_openfile_out.write(line)
skip_a_line = False
pdf_openfile_in.close()
pdf_openfile_out.close()
print("Rebuilding xref table (post newfile creation)")
rebuildXrefTable(pdf_dataout_file)
def rebuildXrefTable(pdf_file_in, pdf_file_out=None):
# Updating the xref table:
# * Assumes uncompressed PDF file
# To do this I need the number of bytes that precede and object (this is used as a reference).
# So, each line I will need to count the byte number and tally up
# When an object is found, the byte_count will be added to the reference list and then used to create the xref table
# Also need to update the "startxref" at the bottom (similar principle).
if (pdf_file_out == None): pdf_file_out = os.path.join(os.path.dirname(pdf_file_in), "rebuilt_xref_pdf.pdf")
print("Updating xref table of: " + os.path.basename(pdf_file_in))
byte_count = 0
xref_start = 0
object_location_reference = []
updating_xref_stage = 1
pdf_openfile_in = open(pdf_file_in, "rb")
pdf_openfile_out = open(pdf_file_out, "wb")
pdf_file_lines = pdf_openfile_in.readlines()
for line in pdf_file_lines:
current_line_val = line.decode("Latin-1").strip()
if (" obj" in current_line_val):
# Check if the place is an object loc, store byte reference and object index
obj_ref_index = current_line_val.split(" ")[0]
print("Found new object (index, location): (" + str(obj_ref_index) + ", " + str(byte_count) + ")")
object_location_reference.append((int(obj_ref_index), byte_count))
elif ("startxref" in current_line_val):
# This is the last thing to edit (right at the bottom, update the xref start location and then add the file end.
print("Updating the xref start value with new data...")
new_line = "startxref\n" + str(xref_start) + "\n" + r"%%EOF"
pdf_openfile_out.write(new_line.encode("latin-1"))
break
elif ("xref" in current_line_val):
print("Recording the new xref byte location")
preceeding_str = current_line_val.split("xref")[0]
preceeding_count = len(preceeding_str.encode("latin-1"))
xref_start = byte_count + preceeding_count # used at the end
updating_xref_stage = 2
elif (updating_xref_stage == 2 or updating_xref_stage == 3):
# This stage simply skips the first 2 xref data lines (and prints it o the new file as is)
updating_xref_stage += 1
elif (updating_xref_stage == 4):
print("Creating new xref object byte location table...")
object_location_reference.sort() # Sort the collected xref locations by their object index.
# Now add the new xref data information
for xref_loc in object_location_reference:
new_val = str(xref_loc[1]).zfill(10) # Pad the number out
new_val = new_val + " 00000 n \n"
pdf_openfile_out.write(new_val.encode("latin-1"))
updating_xref_stage = 5
elif (updating_xref_stage == 5):
# Stage 5 doesn't record the read in lines into new file, step 6 will.
if ("trailer" in current_line_val): updating_xref_stage = 6
# Write to file
if not (updating_xref_stage == 5):
pdf_openfile_out.write(line)
byte_count += len(line)
pdf_openfile_in.close()
pdf_openfile_out.close()
# To use the PDF compression:
crunchPdfImages(r"C:\Users\Person\Desktop\Test Folder\Pdf File.pdf")
我的目标是拥有一个 Python 脚本，它将获取 PDF，提取其图像，compress/resize 它们，然后将此新数据推送到 PDF，这将产生一个新的，更小的 PDF。
到目前为止，除了用正确的对应物替换图像数据外，我已经完成了所有工作。我找到了图像数据所在的正确位置（在“stream”和“streamend”标签之间）。
这是我的代码（已更新）：
def crunchPdfImages(file_to_crunch, max_width=1200, max_height=628):
page_ratio = max_width / max_height
working_folder = os.path.dirname(file_to_crunch)
working_dir = os.path.join(working_folder, "temp_working_dir")
if not (os.path.exists(working_dir)): os.mkdir(working_dir)
# Get all the image...
extractPDFImages(file_to_crunch, working_dir)
# Compress all the images... (no resize)
all_image_list = [entry.path for entry in os.scandir(working_dir) if isImage(entry.path)]
for an_image in all_image_list:
img_picture = Image.open(an_image).convert("RGB")
img_picture.save(an_image, "JPEG", optimize=True)
# Uncompress the PDF
pdf_folder = os.path.join(working_dir, "pdf_uncompressed")
if not (os.path.exists(pdf_folder)): os.mkdir(pdf_folder)
pdf_datain_file = os.path.join(pdf_folder, "uncompressed_pdf.pdf")
pdf_dataout_file = os.path.join(pdf_folder, "new_images_pdf.pdf")
pypdftk.uncompress('"' + file_to_crunch + '"', pdf_datain_file)
# Now get to work...
# The PDF is comprised of objects, some of which are lablled as images.
# Each image has the line "/Subtype /Image" before the "stream" which is then ended by "endstream" then "endobj".
# In between the stream and endstream is the encoded image data... hopefully I can replace this in the same order that
# the images were taken out.
picture_replace_count = 0
pdf_openfile_in = open(pdf_datain_file, "rb")
pdf_openfile_out = open(pdf_dataout_file, "wb")
pdf_file_lines = pdf_openfile_in.readlines()
looking_for_next_stream = False
found_stream_and_removing = False
updating_xref_stage = 0
skip_a_line = False
for line in pdf_file_lines:
new_line_addition = "" # For adding to byte count, resetting to null here just in case
current_line_val = line.decode("Latin-1").strip()
if (looking_for_next_stream):
# Last image tag has been found but not dealt with, so find the stream then
if (current_line_val[:8] == "/Length "):
# Update the length
skip_a_line = True
new_img_size = str(os.path.getsize(all_image_list[picture_replace_count]))
new_line = r"/Length " + new_img_size + "\n"
pdf_openfile_out.write(new_line.encode("latin-1")) # add new line
if (current_line_val == "stream"):
print("Stream start found... skipping stream information")
looking_for_next_stream = False # it's been found
found_stream_and_removing = True # time to delete
new_line_addition = "stream\n".encode("latin-1")
pdf_openfile_out.write(new_line_addition) # add the line in or it will be skipped
elif (found_stream_and_removing):
if (current_line_val == "endstream"):
print("Stream end found")
found_stream_and_removing = False # Passed through all image data line
# Now, add in the new image data and continue on.
print("Adding new image data...")
#new_image_file = open(all_image_list[picture_replace_count], "rb")
img = Image.open(all_image_list[picture_replace_count], mode='r')
img_byte_arr = io.BytesIO()
img.save(img_byte_arr, format='JPEG')
img_byte_arr = img_byte_arr.getvalue()
pdf_openfile_out.write(img_byte_arr)
new_line_addition = img_byte_arr
"""
for imgline in new_image_file.readlines():
#pdf_openfile_out.write(imgline.encode("Latin-1"))
#pdf_openfile_out.write(imgline)
pass
#pdf_openfile_out.write("[IMAGEADD]".encode("latin-1")) # add new line
"""
#new_image_file.close()
picture_replace_count += 1
print("New image added.")
pdf_openfile_out.write("\n".encode("latin-1")) # add new line
if (picture_replace_count >= len(all_image_list)):
updating_xref_stage = 1 # All images replaced, now edit the xref.
elif (current_line_val == r"/Subtype /Image"):
print("Found an image place, number " + str(picture_replace_count))
print("Looking for stream start...")
looking_for_next_stream = True
# Find next
if not (found_stream_and_removing) and not (skip_a_line) and not (updating_xref_stage == 4):
pdf_openfile_out.write(line)
skip_a_line = False
pdf_openfile_in.close()
pdf_openfile_out.close()
print("Rebuilding xref table (post newfile creation)")
rebuildXrefTable(pdf_dataout_file)
并重建外部参照 table（根据此处的评论）我 运行 以下函数。我确实尝试在之前的函数中执行此操作，但数据最终以不同的大小输出。我还没有想出如何准确地将照片日期推送到 PDF 流中。
def rebuildXrefTable(pdf_file_in, pdf_file_out=None):
# Updating the xref table:
# * Assumes uncompressed PDF file
# To do this I need the number of bytes that precede and object (this is used as a reference).
# So, each line I will need to count the byte number and tally up
# When an object is found, the byte_count will be added to the reference list and then used to create the xref table
# Also need to update the "startxref" at the bottom (similar principle).
if (pdf_file_out == None): pdf_file_out = os.path.join(os.path.dirname(pdf_file_in), "rebuilt_xref_pdf.pdf")
print("Updating xref table of: " + os.path.basename(pdf_file_in))
byte_count = 0
xref_start = 0
object_location_reference = []
updating_xref_stage = 1
pdf_openfile_in = open(pdf_file_in, "rb")
pdf_openfile_out = open(pdf_file_out, "wb")
pdf_file_lines = pdf_openfile_in.readlines()
for line in pdf_file_lines:
current_line_val = line.decode("Latin-1").strip()
if (" obj" in current_line_val):
# Check if the place is an object loc, store byte reference and object index
obj_ref_index = current_line_val.split(" ")[0]
print("Found new object (index, location): (" + str(obj_ref_index) + ", " + str(byte_count) + ")")
object_location_reference.append((int(obj_ref_index), byte_count))
elif ("startxref" in current_line_val):
# This is the last thing to edit (right at the bottom, update the xref start location and then add the file end.
print("Updating the xref start value with new data...")
new_line = "startxref\n" + str(xref_start) + "\n" + r"%%EOF"
pdf_openfile_out.write(new_line.encode("latin-1"))
break
elif ("xref" in current_line_val):
print("Recording the new xref byte location")
preceeding_str = current_line_val.split("xref")[0]
preceeding_count = len(preceeding_str.encode("latin-1"))
xref_start = byte_count + preceeding_count # used at the end
updating_xref_stage = 2
elif (updating_xref_stage == 2 or updating_xref_stage == 3):
# This stage simply skips the first 2 xref data lines (and prints it o the new file as is)
updating_xref_stage += 1
elif (updating_xref_stage == 4):
print("Creating new xref object byte location table...")
object_location_reference.sort() # Sort the collected xref locations by their object index.
# Now add the new xref data information
for xref_loc in object_location_reference:
new_val = str(xref_loc[1]).zfill(10) # Pad the number out
new_val = new_val + " 00000 n \n"
pdf_openfile_out.write(new_val.encode("latin-1"))
updating_xref_stage = 5
elif (updating_xref_stage == 5):
# Stage 5 doesn't record the read in lines into new file
if ("trailer" in current_line_val): updating_xref_stage = 5
# Write to file
if not (updating_xref_stage == 5):
pdf_openfile_out.write(line)
byte_count += len(line)
pdf_openfile_in.close()
pdf_openfile_out.close()
外部参照 table 是准确的并且指向正确的字节位置，我还确保它的顺序正确（使用对象索引号，而不是它在文件中出现的顺序--这与原始 PDF 文档匹配）。
如果我不尝试替换任何东西而只是将数据输出到新的 PDF 文件中，它就可以工作并且我可以打开新文件。但是，当插入替换的JPG数据时，PDF无法打开，因为它已损坏。
我不知道如何将压缩图像中的正确数据推送到 PDF 文件。
我也试过像这样简单地推送JPG数据：
image = open(all_image_list[picture_replace_count], 'rb')
pdf_openfile_out.write(image.read())
image.close()
使用：Python 3.8
感谢这里的评论，我已经解决了这个问题。必须重建外部参照 table，并将 JPG 数据作为一个整体放置。这是工作代码：
def crunchPdfImages(file_to_crunch):
working_folder = os.path.dirname(file_to_crunch)
working_dir = os.path.join(working_folder, "temp_working_dir")
if not (os.path.exists(working_dir)): os.mkdir(working_dir)
# Get all the image...
extractPDFImages(file_to_crunch, working_dir)
# Compress all the images... (no resize, just optimise)
all_image_list = [entry.path for entry in os.scandir(working_dir) if isImage(entry.path)]
if (len(all_image_list) > 0):
for an_image in all_image_list:
img_picture = Image.open(an_image).convert("RGB")
img_picture.save(an_image, "JPEG", optimize=True)
else:
print("No images found in PDF...")
# Uncompress the PDF
pdf_folder = os.path.join(working_dir, "pdf_uncompressed")
if not (os.path.exists(pdf_folder)): os.mkdir(pdf_folder)
pdf_datain_file = os.path.join(pdf_folder, "uncompressed_pdf.pdf")
pdf_dataout_file = os.path.join(pdf_folder, "new_images_pdf.pdf")
print("Uncompressing PDF...")
pypdftk.uncompress('"' + file_to_crunch + '"', '"' + pdf_datain_file + '"')
# Now get to work...
# The PDF is comprised of objects, some of which are lablled as images.
# Each image has the line "/Subtype /Image" before the "stream" which is then ended by "endstream" then "endobj".
# In between the stream and endstream is the encoded image data... hopefully I can replace this in the same order that
# the images were taken out.
picture_replace_count = 0
pdf_openfile_in = open(pdf_datain_file, "rb")
pdf_openfile_out = open(pdf_dataout_file, "wb")
pdf_file_lines = pdf_openfile_in.readlines()
looking_for_next_stream = False
found_stream_and_removing = False
skip_a_line = False
for line in pdf_file_lines:
new_line_addition = "" # For adding to byte count, resetting to null here just in case
current_line_val = line.decode("Latin-1").strip()
if (looking_for_next_stream):
# Last image tag has been found but not dealt with, so find the stream then
if (current_line_val[:8] == "/Length "):
# Update the length
skip_a_line = True
new_img_size = str(os.path.getsize(all_image_list[picture_replace_count]))
new_line = r"/Length " + new_img_size + "\n"
pdf_openfile_out.write(new_line.encode("latin-1")) # add new line
if (current_line_val == "stream"):
print("Stream start found... skipping stream information")
looking_for_next_stream = False # it's been found
found_stream_and_removing = True # time to delete
new_line_addition = "stream\n".encode("latin-1")
pdf_openfile_out.write(new_line_addition) # add the line in or it will be skipped
elif (found_stream_and_removing):
if (current_line_val == "endstream"):
print("Stream end found")
found_stream_and_removing = False # Passed through all image data line
# Now, add in the new image data and continue on.
print("Adding new image data...")
image = open(all_image_list[picture_replace_count], 'rb')
pdf_openfile_out.write(image.read())
image.close()
picture_replace_count += 1
pdf_openfile_out.write("\n".encode("latin-1")) # add new line
elif (current_line_val == r"/Subtype /Image"):
print("Found an image place, number " + str(picture_replace_count))
print("Looking for stream start...")
looking_for_next_stream = True
# Find next
if not (found_stream_and_removing) and not (skip_a_line):
pdf_openfile_out.write(line)
skip_a_line = False
pdf_openfile_in.close()
pdf_openfile_out.close()
print("Rebuilding xref table (post newfile creation)")
rebuildXrefTable(pdf_dataout_file)
def rebuildXrefTable(pdf_file_in, pdf_file_out=None):
# Updating the xref table:
# * Assumes uncompressed PDF file
# To do this I need the number of bytes that precede and object (this is used as a reference).
# So, each line I will need to count the byte number and tally up
# When an object is found, the byte_count will be added to the reference list and then used to create the xref table
# Also need to update the "startxref" at the bottom (similar principle).
if (pdf_file_out == None): pdf_file_out = os.path.join(os.path.dirname(pdf_file_in), "rebuilt_xref_pdf.pdf")
print("Updating xref table of: " + os.path.basename(pdf_file_in))
byte_count = 0
xref_start = 0
object_location_reference = []
updating_xref_stage = 1
pdf_openfile_in = open(pdf_file_in, "rb")
pdf_openfile_out = open(pdf_file_out, "wb")
pdf_file_lines = pdf_openfile_in.readlines()
for line in pdf_file_lines:
current_line_val = line.decode("Latin-1").strip()
if (" obj" in current_line_val):
# Check if the place is an object loc, store byte reference and object index
obj_ref_index = current_line_val.split(" ")[0]
print("Found new object (index, location): (" + str(obj_ref_index) + ", " + str(byte_count) + ")")
object_location_reference.append((int(obj_ref_index), byte_count))
elif ("startxref" in current_line_val):
# This is the last thing to edit (right at the bottom, update the xref start location and then add the file end.
print("Updating the xref start value with new data...")
new_line = "startxref\n" + str(xref_start) + "\n" + r"%%EOF"
pdf_openfile_out.write(new_line.encode("latin-1"))
break
elif ("xref" in current_line_val):
print("Recording the new xref byte location")
preceeding_str = current_line_val.split("xref")[0]
preceeding_count = len(preceeding_str.encode("latin-1"))
xref_start = byte_count + preceeding_count # used at the end
updating_xref_stage = 2
elif (updating_xref_stage == 2 or updating_xref_stage == 3):
# This stage simply skips the first 2 xref data lines (and prints it o the new file as is)
updating_xref_stage += 1
elif (updating_xref_stage == 4):
print("Creating new xref object byte location table...")
object_location_reference.sort() # Sort the collected xref locations by their object index.
# Now add the new xref data information
for xref_loc in object_location_reference:
new_val = str(xref_loc[1]).zfill(10) # Pad the number out
new_val = new_val + " 00000 n \n"
pdf_openfile_out.write(new_val.encode("latin-1"))
updating_xref_stage = 5
elif (updating_xref_stage == 5):
# Stage 5 doesn't record the read in lines into new file, step 6 will.
if ("trailer" in current_line_val): updating_xref_stage = 6
# Write to file
if not (updating_xref_stage == 5):
pdf_openfile_out.write(line)
byte_count += len(line)
pdf_openfile_in.close()
pdf_openfile_out.close()
# To use the PDF compression:
crunchPdfImages(r"C:\Users\Person\Desktop\Test Folder\Pdf File.pdf")