embed the meta info into PNG image file.

png_info.py

# -*- mode: python; coding: utf-8-unix -*-
#
#
# @ref: https://pillow.readthedocs.io/en/3.1.x/PIL.html?highlight=PngInfo#PIL.PngImagePlugin.PngInfo
#
import os
from datetime import datetime
from optparse import OptionParser
from PIL.PngImagePlugin import PngImageFile, PngInfo

# PNG SIGNATURE(8)
# IHDR(25)
# 00000000: 8950 4e47 0d0a 1a0a 0000 000d 4948 4452  .PNG........IHDR
# 00000010: 0000 0227 0000 019d 0802 0000 0046 8b44  ...'.........F.D
# 00000020: 0400 0000 0970 4859 7300 000b 1300 000b  .....pHYs.......
# 00000030: 1301 009a 9c18 0000 0a4f 6943 4350 5068  .........OiCCPPh
#   ... 
# 00012fd0: 5863 8d35 d658 638d 35d6 5863 8d4d 61ff  Xc.5.Xc.5.Xc.Ma.
# IEND(12)
# 00012fe0: ff01 003f bd27 8a31 632f 0900 0000 0049  ...?.'.1c/.....I
# 00012ff0: 454e 44ae 4260 82                        END.B'.


#
#
#
def inspect_img( img ):
    targetImage = PngImageFile(img)
    print(targetImage.text)
    return (targetImage.text)

#
#
#
# @ref: iTXt chunk: add_itxt(key, value, lang='', tkey='', zip=False)
# @ref: tEXt chunk: add_text(key, value, zip=0)
#
def embeded_text_img( img, img_save, metas, debug=False ):
    wellknown_keys = [
        'Title', 'Author', 'Description', 'Copyright', 'Creation Time',
        'Software', 'Disclaimer', 'Warning', 'Source', 'Comment' ]
    targetImage = PngImageFile(img)

    if ((not metas is None) and (len(metas.keys()) > 0)):
        metadata = PngInfo()

        for ky in metas.keys():
            metadata.add_text(ky, metas[ky])

        targetImage.save(img_save, pnginfo=metadata)

    if debug:
        inspect_img( img_save )
    return

#
#
#
if __name__ == "__main__":
    parser = OptionParser()
    parser.add_option("-q", "--quiet",
                      action="store_false", dest="verbose", default=True,
                      help="don't print status messages to stdout")

    (options, args) = parser.parse_args()
    sample = { "TestMark" : "Hi There" }
    for tp in args:
        base = os.path.splitext(os.path.basename(tp))[0]
        now = datetime.now()
        timestamp = now.strftime("%Y/%m/%d_%H:%M:%S")
        sample[ 'Creation Time' ] = timestamp
        sample[ 'Software' ] = "png_info.py"
        sample[ 'Source' ] = tp
        embeded_text_img(tp, base + "_save.png", sample, True)