Import Upstream version 0.3.3

1 files changed, 125 insertions, 0 deletions

diff --git a/src/jp2.py b/src/jp2.py
new file mode 100644
index 0000000..30edb7e
--- /dev/null
+++ b/src/jp2.py
@@ -0,0 +1,125 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2013 Johannes 'josch' Schauer <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)