Why my code not correctly split every page in a scanned pdf?

Question

Update: Thanks to stardt whose script works! The pdf is a page of another one. I tried the script on the other one, and it also correctly spit each pdf page

Answer 1

Your code assumes that p.mediaBox.lowerLeft is (0,0) but it is actually (0, 497)

This works for the file you provided:

#!/usr/bin/env python
import copy, sys
from pyPdf import PdfFileWriter, PdfFileReader
input = PdfFileReader(sys.stdin)
output = PdfFileWriter()
for i in range(input.getNumPages()):
    p = input.getPage(i)
    q = copy.copy(p)

    bl = p.mediaBox.lowerLeft
    ur = p.mediaBox.upperRight

    print >> sys.stderr, 'splitting page',i
    print >> sys.stderr, '\tlowerLeft:',p.mediaBox.lowerLeft
    print >> sys.stderr, '\tupperRight:',p.mediaBox.upperRight

    p.mediaBox.upperRight = (ur[0], (bl[1]+ur[1])/2)
    p.mediaBox.lowerLeft = bl

    q.mediaBox.upperRight = ur
    q.mediaBox.lowerLeft = (bl[0], (bl[1]+ur[1])/2)
    if i%2==0:
        output.addPage(q)
        output.addPage(p)
    else:
        output.addPage(p)
        output.addPage(q)

output.write(sys.stdout)

Answer 2

@stardt's code was quite useful, but I had problems to split a batch of pdf files with different orientations. Here's a more general function that will work no matter what the page orientation is:

import copy
import math
import pyPdf

def split_pages(src, dst):
    src_f = file(src, 'r+b')
    dst_f = file(dst, 'w+b')

    input = pyPdf.PdfFileReader(src_f)
    output = pyPdf.PdfFileWriter()

    for i in range(input.getNumPages()):
        p = input.getPage(i)
        q = copy.copy(p)
        q.mediaBox = copy.copy(p.mediaBox)

        x1, x2 = p.mediaBox.lowerLeft
        x3, x4 = p.mediaBox.upperRight

        x1, x2 = math.floor(x1), math.floor(x2)
        x3, x4 = math.floor(x3), math.floor(x4)
        x5, x6 = math.floor(x3/2), math.floor(x4/2)

        if x3 > x4:
            # horizontal
            p.mediaBox.upperRight = (x5, x4)
            p.mediaBox.lowerLeft = (x1, x2)

            q.mediaBox.upperRight = (x3, x4)
            q.mediaBox.lowerLeft = (x5, x2)
        else:
            # vertical
            p.mediaBox.upperRight = (x3, x4)
            p.mediaBox.lowerLeft = (x1, x6)

            q.mediaBox.upperRight = (x3, x6)
            q.mediaBox.lowerLeft = (x1, x2)

        output.addPage(p)
        output.addPage(q)

    output.write(dst_f)
    src_f.close()
    dst_f.close()

Answer 3

I'd like to add that you have to pay attention that your mediaBox variables are not shared across the copies p and q. This can easily happen if you read from p.mediaBox before taking the copy.

In that case, writing to e.g. p.mediaBox.upperRight may modify q.mediaBox and vice versa.

@moraes' solution takes care of this by explicitly copying the mediaBox.