iOS PNG uncrushers based on http://www.axelbrz.com.ar/?mod=iphone-png-images-normalizer with a fix for multiple IDAT

ipin.py

#---
# iPIN - iPhone PNG Images Normalizer v1.0
# Copyright (C) 2007
#
# Author:
#  Axel E. Brzostowski
#  http://www.axelbrz.com.ar/
#  [email protected]
# 
# References:
#  http://iphone.fiveforty.net/wiki/index.php/PNG_Images
#  http://www.libpng.org/pub/png/spec/1.2/PNG-Contents.html
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
#---

from struct import *
from zlib import *
import stat
import sys
import os

def getNormalizedPNG(filename):
    pngheader = "\x89PNG\r\n\x1a\n"
    
    file = open(filename, "rb")
    oldPNG = file.read()
    file.close()

    if oldPNG[:8] != pngheader:
        return None
    
    newPNG = oldPNG[:8]
    
    chunkPos = len(newPNG)
    
    idatAcc = ""
    breakLoop = False
    
    # For each chunk in the PNG file    
    while chunkPos < len(oldPNG):
        skip = False
        
        # Reading chunk
        chunkLength = oldPNG[chunkPos:chunkPos+4]
        chunkLength = unpack(">L", chunkLength)[0]
        chunkType = oldPNG[chunkPos+4 : chunkPos+8]
        chunkData = oldPNG[chunkPos+8:chunkPos+8+chunkLength]
        chunkCRC = oldPNG[chunkPos+chunkLength+8:chunkPos+chunkLength+12]
        chunkCRC = unpack(">L", chunkCRC)[0]
        chunkPos += chunkLength + 12

        # Parsing the header chunk
        if chunkType == "IHDR":
            width = unpack(">L", chunkData[0:4])[0]
            height = unpack(">L", chunkData[4:8])[0]

        # Parsing the image chunk
        if chunkType == "IDAT":
            # Store the chunk data for later decompression
            idatAcc += chunkData
            skip = True

        # Removing CgBI chunk        
        if chunkType == "CgBI":
            skip = True

        # Add all accumulated IDATA chunks
        if chunkType == "IEND":
            try:
                # Uncompressing the image chunk
                bufSize = width * height * 4 + height
                chunkData = decompress( idatAcc, -15, bufSize)
                
            except Exception, e:
                # The PNG image is normalized
                print e
                return None

            chunkType = "IDAT"

            # Swapping red & blue bytes for each pixel
            newdata = ""
            for y in xrange(height):
                i = len(newdata)
                newdata += chunkData[i]
                for x in xrange(width):
                    i = len(newdata)
                    newdata += chunkData[i+2]
                    newdata += chunkData[i+1]
                    newdata += chunkData[i+0]
                    newdata += chunkData[i+3]

            # Compressing the image chunk
            chunkData = newdata
            chunkData = compress( chunkData )
            chunkLength = len( chunkData )
            chunkCRC = crc32(chunkType)
            chunkCRC = crc32(chunkData, chunkCRC)
            chunkCRC = (chunkCRC + 0x100000000) % 0x100000000
            breakLoop = True

        if not skip:
            newPNG += pack(">L", chunkLength)
            newPNG += chunkType
            if chunkLength > 0:
                newPNG += chunkData
            newPNG += pack(">L", chunkCRC)
        if breakLoop:
            break
        
    return newPNG

def updatePNG(filename):
    data = getNormalizedPNG(filename)
    if data != None:
        file = open(filename, "wb")
        file.write(data)
        file.close()
        return True
    return data

def getFiles(base):
    global _dirs
    global _pngs
    if base == ".":
        _dirs = []
        _pngs = []
        
    if base in _dirs:
        return

    files = os.listdir(base)
    for file in files:
        filepath = os.path.join(base, file)
        try:
            st = os.lstat(filepath)
        except os.error:
            continue
        
        if stat.S_ISDIR(st.st_mode):
            if not filepath in _dirs:
                getFiles(filepath)
                _dirs.append( filepath )
                
        elif file[-4:].lower() == ".png":
            if not filepath in _pngs:
                _pngs.append( filepath )
            
    if base == ".":
        return _dirs, _pngs

print "-----------------------------------"
print " iPhone PNG Images Normalizer v1.0"
print "-----------------------------------"
print " "
print "[+] Searching PNG files...",
dirs, pngs = getFiles(".")
print "ok"

if len(pngs) == 0:
    print " "
    print "[!] Alert: There are no PNG files found. Move this python file to the folder that contains the PNG files to normalize."
    exit()
    
print " "
print " -  %d PNG files were found at this folder (and subfolders)." % len(pngs)
print " "
while True:
    normalize = raw_input("[?] Do you want to normalize all images (Y/N)? ").lower()
    if len(normalize) > 0 and (normalize[0] == "y" or normalize[0] == "n"):
        break

normalized = 0
if normalize[0] == "y":
    for ipng in xrange(len(pngs)):
        perc = (float(ipng) / len(pngs)) * 100.0
        print "%.2f%% %s" % (perc, pngs[ipng])
        if updatePNG(pngs[ipng]):
            normalized += 1
print " "
print "[+] %d PNG files were normalized." % normalized

Great stuff, the only script on the net I've found to work. Thanks!

亲测可用

Great job,I have used it in my jenkins CI scripts.

Great job!!! Thanks!
非常赞啊！

It works perfectly, thanks!

Thank you very much. I tried this code as last hope and it worked. Thanks..