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retrieve / find out an image's dimensions

P: n/a
hey guys

Is there a builtin/standard install method in python for retrieving or
finding out an image's dimensions?

A quick google found me this:
http://www.pythonware.com/library/pi...troduction.htm

but it looks like it is something I will need to install - I'd like to
be able to pass my script around to people without them needing any
additional modules

Any help would be fantastic!

Cheers

Adam
python 2.3.5
osx 10.4.9

Jun 16 '07 #1
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2 Replies


P: n/a
http://www.pycode.com/modules/?id=32

On 6 16 , 6 27 , Adam Teale <a...@lumanation.comwrote:
hey guys

Is there a builtin/standard install method in python for retrieving or
finding out an image's dimensions?

A quick google found me this:http://www.pythonware.com/library/pi...troduction.htm

but it looks like it is something I will need to install - I'd like to
be able to pass my script around to people without them needing any
additional modules

Any help would be fantastic!

Cheers

Adam
python 2.3.5
osx 10.4.9

Jun 16 '07 #2

P: n/a
On 6 16 , 6 27 , Adam Teale <a...@lumanation.comwrote:
hey guys

Is there a builtin/standard install method in python for retrieving or
finding out an image's dimensions?
Sorry, after i review these code in http://www.pycode.com/modules/?id=32,
i found some(not just a few) *BUGS* in it.
I must apologize to you for this.
I have rewrite the moudle.
please have a try.
"""Recognize image file formats and size based on their first few
bytes."""
# Perl Image::Size module clone
# see more http://search.cpan.org/author/RJRAY/.../Image/Size.pm
# rewrited by jigloo(ph**@live.com)
# GPL-2 license

__all__ = ["what", "imgsz", "size"]

import os # for os.path os.error sys.stderr
import StringIO # for StringIO.StringIO
import struct # for unpack
import re # for regex

# jpegsize: gets the width and height (in pixels) of a jpeg file
#
def jpegsize(stream):
(x, y, error) = (None, None, "could not determine JPEG size")

# Dummy read to skip header ID
stream.read(2)
while True:
# Extract the segment header.
(marker, code, length) = struct.unpack("!BBH", stream.read(4))

# Verify that it's a valid segment.
if marker != 0xFF:
# Was it there?
error = "JPEG marker not found"
break
elif code >= 0xC0 and code <= 0xC3:
# Segments that contain size info
(y, x) = struct.unpack("!xHH", stream.read(5))
error = "no error"
break
else:
# Dummy read to skip over data
stream.read(length - 2)

return ("JPEG", x, y, error)
# bmpsize: size a Windows-ish BitMaP image
#
def bmpsize(stream):
(x, y, error) = (None, None, "Unable to determine size of BMP data")

# Dummy read to skip header data
stream.read(18)
(x, y) = struct.unpack("<LL", stream.read(8))
if x 0 and y 0:
error = "no error"

return ("BMP", x, y, error)
# pngsize : gets the width & height (in pixels) of a png file
# cor this program is on the cutting edge of technology! (pity it's
blunt!)
#
def pngsize(stream):
(x, y, error) = (None, None, "could not determine PNG size")

# Dummy read to skip header data
stream.read(12)
if stream.read(4) == "IHDR":
(x, y) = struct.unpack("!LL", stream.read(8))
error = "no error"

return ("PNG", x, y, error)

# gifsize : Subroutine gets the size of the specified GIF
#
# Default behavior for GIFs is to return the "screen" size
GIF_BEHAVIOR = 0
#
def gifsize(stream):

if GIF_BEHAVIOR 2:
return ("GIF", 0, 0, "Out-of-range value for GIF_BEHAVIOR: %d" %
GIF_BEHAVIOR)

# Skip over the identifying string, since we already know this is a
GIF
type = stream.read(6)
buf = stream.read(5)
if len(buf) != 5:
return ("GIF", 0, 0, "Invalid/Corrupted GIF (bad header)")
(sw, sh, x) = struct.unpack("<HHB", buf)
if GIF_BEHAVIOR == 0:
return ("GIF", sw, sh, "no error")

return ("GIF", None, None, "Invalid/Corrupted GIF (missing image
header?)")

# ppmsize : gets data on the PPM/PGM/PBM family.
#
def ppmsize(stream):
(mime, x, y, error) = ("PPM", None, None, "Unable to determine size
of PPM/PGM/PBM data")

header = stream.read(1024)
# PPM file of some sort
re.sub(r"^\#.*", "", header, re.M)
m = re.match(r"^(P[1-6])\s+(\d+)\s+(\d+)", header, re.S)
if m:
(n, x, y) = m.group(1, 2, 3)
mime = {"P1":"PBM", "P2":"PGM", "P3":"PPM", "P4":"BPM", "P5":"PGM",
"P6":"PPM"}[n]
if n == "P7":
mime = "XV"
m = re.match(r"IMGINFO:(\d+)x(\d+)", header, re.S)
if m:
(x, y) = m.group(1, 2)
error = "no error"
return (mime, int(x), int(y), error)
else:
return (mime, x, y, error)

# xbmsize :
#
def xbmsize(stream):
(x, y, error) = (None, None, "could not determine XBM size")

header = stream.read(1024)

m = re.match(r"^\#define\s*\S*\s*(\d+)\s*\n\#define\s* \S*\s*(\d+)",
header, re.S|re.I)
if m:
(x, y) = m.group(1, 2)
error = "no error"
return ("XBM", int(x), int(y), error)
else:
return ("XBM", x, y, error)
# Size an XPM file by looking for the "X Y N W" line, where X and Y
are
# dimensions, N is the total number of colors defined, and W is the
width of
# a color in the ASCII representation, in characters. We only care
about X & Y.
def xpmsize(stream):
(x, y, error) = (None, None, "could not determine XPM size")

while True:
line = stream.readline()
if line == "":
break
m = re.compile(r"\s*(\d+)\s+(\d+)(\s+\d+\s+\d+){1,2}\s *",
re.M).match(line, 1)
if m:
(x, y) = map(lambda x: int(x), m.group(1, 2))
error = "no error"
break

return ("XPM", x, y, error)
# tiffsize : size a TIFF image
#
def tiffsize(stream):
(x, y, error) = (None, None, "Unable to determine size of TIFF data")

be = "!" # Default to big-endian; I like it better
if stream.read(4) == "II\x2a\x00": # little-endian
be = "<"

# Set up an association between data types and their corresponding
# pack/unpack specification. Don't take any special pains to deal
with
# signed numbers; treat them as unsigned because none of the image
# dimensions should ever be negative. (I hope.)
packspec = [ None, # nothing (shouldn't happen)
"Bxxx", # BYTE (8-bit unsigned integer)
None, # ASCII
be+"Hxx", # SHORT (16-bit unsigned integer)
be+"L", # LONG (32-bit unsigned integer)
None, # RATIONAL
"bxxx", # SBYTE (8-bit signed integer)
None, # UNDEFINED
be+"Hxx", # SSHORT (16-bit unsigned integer)
be+"L" # SLONG (32-bit unsigned integer)
]

offset = struct.unpack(be+"L", stream.read(4))[0] # Get offset to IFD

ifd = stream.read(2) # Get number of directory entries
num_dirent = struct.unpack(be+"H", ifd)[0] # Make it useful
num_dirent = offset + (num_dirent * 12) # Calc. maximum offset of IFD

# Do all the work
ifd = ''
tag = 0
type = 0
while x is None or y is None:
ifd = stream.read(12) # Get first directory entry
if ifd == "" or stream.tell() num_dirent:
break
tag = struct.unpack(be+"H", ifd[:2])[0] # ...and decode its tag
type = struct.unpack(be+"H", ifd[2:2+2])[0] # ...and the data type
# Check the type for sanity.
if type len(packspec) or packspec[type] is None:
continue
if tag == 0x0100: # ImageWidth (x)
# Decode the value
x = struct.unpack(packspec[type], ifd[8:4+8])[0]
elif tag == 0x0101: # ImageLength (y)
# Decode the value
y = struct.unpack(packspec[type], ifd[8:4+8])[0]

# Decide if we were successful or not
if x and y:
error = "no error"
else:
error = ""
if x is None:
error = "ImageWidth "
if y is None:
if error != "":
error = error + "and "
error = error + "ImageWidth "
error = error + "tag(s) could not be found"

return ("TIFF", x, y, error)

# psdsize : determine the size of a PhotoShop save-file (*.PSD)
#
def psdsize(stream):
(x, y, error) = (None, None, "could not determine PSD size")

stream.read(14)
(y, x) = struct.unpack("!LL", stream.read(8))
if x 0 and y 0:
error = "no error"
return ("PSD", x, y, error)

# pcdsize :
# Kodak photo-CDs are weird. Don't ask me why, you really don't want
details.
PCD_MAP = { "base/16" : [ 192, 128 ],
"base/4" : [ 384, 256 ],
"base" : [ 768, 512 ],
"base4" : [ 1536, 1024 ],
"base16" : [ 3072, 2048 ],
"base64" : [ 6144, 4096 ]}
# Default scale for PCD images
PCD_SCALE = "base";
#
def pcdsize(stream):
(x, y, error) = (None, None, "Unable to determine size of PCD data")

buff = strean.read(0xf00)
if buff[0x800:3+0x800] != "PCD":
error = "Invalid/Corrupted PCD (bad header)"
return ("PCD", x, y, error)

orient = ord(buff[0x0e02:1+0x0e02]) & 1 # Clear down to one bit
if orient:
(x, y) = PCD_MAP[PCD_SCALE]
else:
(y, x) = PCD_MAP[PCD_SCALE]
error = "no error"
return ("PCD", x, y, error)
# swfsize :
#
def swfsize(stream):
(x, y, error) = (None, None, "not implemented. --I hate swf :(")

return ("SWF", x, y, error)

# swfmxsize :
#
def swfmxsize(stream):
(x, y, error) = (None, None, "not implemented. --I hate swf :(")

return ("SWF", x, y, error)

# mngsize : gets the width and height (in pixels) of an MNG file.
#
# Basically a copy of pngsize.
def mngsize(stream):
(x, y, error) = (None, None, "could not determine MNG size")

stream.read(12)
if stream.read(4) == "MHDR":
# MHDR = Image Header
(x, y) = struct.unpack("!LL", stream.read(8))
error = "MNG"
else:
error = "Invalid/Corrupted MNG (bad header)"

return ("MNG", x, y, error)

# type_map used in function type_map_match
type_map = { re.compile(r"^\xFF\xD8") : ["JPEG", jpegsize],
re.compile(r"^BM") : ["BMP", bmpsize],
re.compile(r"^\x89PNG\x0d\x0a\x1a\x0a") : ["PNG", pngsize],
re.compile(r"^P[1-7]") : ["PPM", ppmsize], # also XVpics
re.compile(r"\#define\s+\S+\s+\d+") : ["XBM", xbmsize],
re.compile(r"\/\* XPM \*\/") : ["XPM", xpmsize],
re.compile(r"^MM\x00\x2a") : ["TIFF", tiffsize],
re.compile(r"^II\x2a\x00") : ["TIFF", tiffsize],
re.compile(r"^8BPS") : ["PSD", psdsize],
re.compile(r"^PCD_OPA") : ["PCD", pcdsize],
re.compile(r"^FWS") : ["SWF", swfsize],
re.compile(r"^CWS") : ["SWF", swfmxsize],
re.compile(r"^\x8aMNG\x0d\x0a\x1a\x0a") : ["MNG", mngsize],
re.compile(r"^GIF8[7,9]a") : ["GIF", gifsize]}
# type_map_match to get MIME-TYPE and callback function
def type_map_match(buffer):
for rx in type_map.keys():
if rx.match(buffer):
return type_map[rx]
else:
return None

# Recognize image headers
#
def what(filename):
try:
f = open(filename, "rb")
h = f.read(512)
except IOError:
print "IOError %s\n" % os.error
finally:
if f: f.close()
m = type_map_match(h)
if m:
return m[0]
return None
# size: size a image from buffer
#
def size(buffer):
m = type_map_match(buffer)
if m:
return (m[1])(StringIO.StringIO(buffer))
else:
return (None, None, None, "Unable to Recognize image file format")

# imgsz: size a image by file name
#
def imgsz(path):
(type, x, y, error) = (None, None, None, "Unable to Recognize image
file format")
f = None
try:
f = open(path, "rb")
header = f.read(256)
f.seek(0)
m = type_map_match(header)
if m:
(type, x, y, error) = (m[1])(f)
except:
print "IOError %s\n" % os.error
return None
finally:
if f: f.close()

return (type, x, y, error)

if __name__ == "__main__":
for filename in [f for f in os.listdir(".") if os.path.isfile(f)]:
print filename, imgsz(filename)
>
A quick google found me this:http://www.pythonware.com/library/pi...troduction.htm

but it looks like it is something I will need to install - I'd like to
be able to pass my script around to people without them needing any
additional modules

Any help would be fantastic!

Cheers

Adam
python 2.3.5
osx 10.4.9

Jun 16 '07 #3

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