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Diffstat (limited to 'env/lib/python3.10/site-packages/jp2.py')
-rw-r--r-- | env/lib/python3.10/site-packages/jp2.py | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/env/lib/python3.10/site-packages/jp2.py b/env/lib/python3.10/site-packages/jp2.py new file mode 100644 index 0000000..ae54746 --- /dev/null +++ b/env/lib/python3.10/site-packages/jp2.py @@ -0,0 +1,124 @@ +#!/usr/bin/env python +# +# Copyright (C) 2013 Johannes Schauer Marin Rodrigues <j.schauer at email.de> +# +# this module is heavily based upon jpylyzer which is +# KB / National Library of the Netherlands, Open Planets Foundation +# and released under the same license conditions +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU Lesser General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# 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 Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + +import struct + + +def getBox(data, byteStart, noBytes): + boxLengthValue = struct.unpack(">I", data[byteStart : byteStart + 4])[0] + boxType = data[byteStart + 4 : byteStart + 8] + contentsStartOffset = 8 + if boxLengthValue == 1: + boxLengthValue = struct.unpack(">Q", data[byteStart + 8 : byteStart + 16])[0] + contentsStartOffset = 16 + if boxLengthValue == 0: + boxLengthValue = noBytes - byteStart + byteEnd = byteStart + boxLengthValue + boxContents = data[byteStart + contentsStartOffset : byteEnd] + return (boxLengthValue, boxType, byteEnd, boxContents) + + +def parse_ihdr(data): + height = struct.unpack(">I", data[0:4])[0] + width = struct.unpack(">I", data[4:8])[0] + return width, height + + +def parse_colr(data): + meth = struct.unpack(">B", data[0:1])[0] + if meth != 1: + raise Exception("only enumerated color method supported") + enumCS = struct.unpack(">I", data[3:])[0] + if enumCS == 16: + return "RGB" + elif enumCS == 17: + return "L" + else: + raise Exception( + "only sRGB and greyscale color space is supported, " "got %d" % enumCS + ) + + +def parse_resc(data): + hnum, hden, vnum, vden, hexp, vexp = struct.unpack(">HHHHBB", data) + hdpi = ((hnum / hden) * (10 ** hexp) * 100) / 2.54 + vdpi = ((vnum / vden) * (10 ** vexp) * 100) / 2.54 + return hdpi, vdpi + + +def parse_res(data): + hdpi, vdpi = None, None + noBytes = len(data) + byteStart = 0 + boxLengthValue = 1 # dummy value for while loop condition + while byteStart < noBytes and boxLengthValue != 0: + boxLengthValue, boxType, byteEnd, boxContents = getBox(data, byteStart, noBytes) + if boxType == b"resc": + hdpi, vdpi = parse_resc(boxContents) + break + return hdpi, vdpi + + +def parse_jp2h(data): + width, height, colorspace, hdpi, vdpi = None, None, None, None, None + noBytes = len(data) + byteStart = 0 + boxLengthValue = 1 # dummy value for while loop condition + while byteStart < noBytes and boxLengthValue != 0: + boxLengthValue, boxType, byteEnd, boxContents = getBox(data, byteStart, noBytes) + if boxType == b"ihdr": + width, height = parse_ihdr(boxContents) + elif boxType == b"colr": + colorspace = parse_colr(boxContents) + elif boxType == b"res ": + hdpi, vdpi = parse_res(boxContents) + byteStart = byteEnd + return (width, height, colorspace, hdpi, vdpi) + + +def parsejp2(data): + noBytes = len(data) + byteStart = 0 + boxLengthValue = 1 # dummy value for while loop condition + width, height, colorspace, hdpi, vdpi = None, None, None, None, None + while byteStart < noBytes and boxLengthValue != 0: + boxLengthValue, boxType, byteEnd, boxContents = getBox(data, byteStart, noBytes) + if boxType == b"jp2h": + width, height, colorspace, hdpi, vdpi = parse_jp2h(boxContents) + break + byteStart = byteEnd + if not width: + raise Exception("no width in jp2 header") + if not height: + raise Exception("no height in jp2 header") + if not colorspace: + raise Exception("no colorspace in jp2 header") + # retrieving the dpi is optional so we do not error out if not present + return (width, height, colorspace, hdpi, vdpi) + + +if __name__ == "__main__": + import sys + + width, height, colorspace = parsejp2(open(sys.argv[1]).read()) + sys.stdout.write("width = %d" % width) + sys.stdout.write("height = %d" % height) + sys.stdout.write("colorspace = %s" % colorspace) |