Crop PDF pages along the spine direction

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Sometimes we need to split or crop double-arranged PDF’s pages along the spine direction (i.e., the middle line) into two new pages, for example, two A4 book pages scanned into a A3 paper, or two A5  book pages arranged in a A4 paper, and so on. Well, there exist some cutting tools to fill the need of cutting double-up pages. However, this cutting/cropping procedure is not automatic, and the repeated cropping-operation is somewhat tedious.

How to get the repeated cropping-manipulations done automatically? Writing a python program is most likely a good choice for such assignment. The following coding is one of such right examples for working well towards cropping double-arranged PDF’s pages, no matter what the page format is.

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1. #coding=utf-8
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2. from PyPDF2 import PdfFileWriter, PdfFileReader
   
3. from copy import copy
   
4. from os import listdir
   
5. import math
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6. 
   
7. def op(pdfInputFileName):
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8.    
   
9.     pdfFileObj = open(pdfInputFileName, 'rb')  
   
10.     pdfReader = PdfFileReader(pdfFileObj)
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11.     pdfWriter = PdfFileWriter()
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12. 
    
13.     for page in [pdfReader.getPage(i) for i in range(pdfReader.getNumPages())]:
    
14.         p = page
    
15.         q = copy(p)
    
16.         q.mediaBox = copy(p.mediaBox)
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17. 
    
18.         x_1, x_2 = p.mediaBox.lowerLeft
    
19.         x_3, x_4 = p.mediaBox.upperRight
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20. 
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21.         x_1, x_2 = math.floor(x_1), math.floor(x_2)
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22.         x_3, x_4 = math.floor(x_3), math.floor(x_4)
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23.         x_5, x_6 = math.floor(x_3/2), math.floor(x_4/2)
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24. 
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25.         if x_3 < x_4: # If your scanned page is normally presented in Adobe Acrobat this "if" statement can be deleted.
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26.             p = p.rotateClockwise(90)
    
27.             q = q.rotateClockwise(90)
    
28.             
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29. 
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30.          if x_3 > x_4: # For editable page
    
31.                             # vertical cropping along Y-axis(x_5 direction, i.e., cutting X-axis)
    
32. 
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33.              p.mediaBox.lowerLeft = (x_1, x_2) # Left part of two-page-rectangle
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34.              p.mediaBox.upperRight = (x_5* 105/100, x_4)
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35. 
    
36.              q.mediaBox.lowerLeft = (x_5* 95/100, x_2)
    
37.              q.mediaBox.upperRight = (x_3, x_4) # Right part of two-page-rectangle
    
38.             
    
39.          else: # For image page
    
40.                # vertical cropping along X-axis(x_6 direction, i.e., cutting Y-axis)
    
41.             
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42.              p.mediaBox.lowerLeft = (x_1, x_2)
    
43.              p.mediaBox.upperRight = (x_3, x_6* 105/100) # Left part of two-page-rectangle
    
44. 
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45.              q.mediaBox.lowerLeft = (x_1, x_6* 95/100)
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46.              q.mediaBox.upperRight = (x_3, x_4) # Right part of two-page-rectangle
    
47. 
    
48.         pdfWriter.addPage(p)
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49.         pdfWriter.addPage(q)
    
50. 
    
51.     pdfOutputFileName = pdfInputFileName[:-4]+'-cut_myself_revised.pdf'
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52.     pdfOutputFile = open(pdfOutputFileName, 'wb')  
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53.     pdfWriter.write(pdfOutputFile)
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54.     pdfFileObj.close()
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55.     pdfOutputFile.close()
    
56.    
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57. # Accomplish the whole execution of a series of PDF-cropping (both editable pages and image pages) automatically in current directory.
    
58. for pdfInputFileName in listdir('.'):
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59.     if pdfInputFileName[-4:]=='.pdf' or pdfInputFileName[-4:]=='.PDF':
    
60.          op(pdfInputFileName)
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61. 
    
62. 
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greatABC005

Thanks for your great work.