The tiff image is a very common image format. It is the preferred format for high resolution printing and is also the most common format for Aerial and Satellite imagery. Upon Googling the tiff standard, I was surprised by how complicated it really was. Apparently, in 1987, all that complication seemed like a good idea. Whatever...
Anyways, here is a Python class that provides a few pieces of information about a given tiff image. It can easily be exended to provide more.
One note about this code: it utilizes Python class descriptors as a way to __set__ the tiff file before making any attempt to parse through the bytes and read a few attributes. In addition, the code utilizes the VERY useful struct module in Python. If you're ever required to parse some bytes, stuct is invaluable.
#PYTHON TiffInfo v1.3
#
#Copyright 2009, PSE Entertainment Corp, All Rights Reserved
#This python class will compute 4 pieces of information from a tiff image
#---ImageWidth, ImageLength, SamplesPerPixel, and ColorProfile---
#
#Usage: instantiate the TiffInfo class, set the tiff file
#then access the properties - something like...
#
# mytiff = TiffInfo()
# mytiff.tiff = 'path/to/some/image.tif'
# mytiff.ColorProfile
# mytiff.ImageLength
# mytiff.ImageWidth
# mytiff.ColorsPerSample
#
#
#ColorProfile will return one of the follow ICC profiles:
# None
# Adobe RGB (1998)
# sRGB IEC61966-2-1
# Kodak ProPhoto RGB
# eciRGB v2
# eciRGB v4
# Other
#
#Any error condition returns -1 as the image attributes.
import binascii, struct
class GetTiffInfo(object):
def __set__(self,inst,tiff):
#This is the method that gets called anytime a tiff
#image is set. It uses the __set__ class descriptor
#and all internal references are based on the instance - inst.
inst.__dict__['tiff'] = tiff
try:
image = open(tiff,'rb')
except:
inst.ColorProfile,inst.ColorsPerSample,inst.ImageLength\
,inst.ImageWidth = self.error()
return
#read the first 2 bytes to know "endian"
start = image.read(2)
endian = binascii.hexlify(start).upper()
if endian == "4949":
symbol = "<"
elif endian == "4D4D":
symbol = ">"
else:
inst.ColorProfile,inst.ColorsPerSample,inst.ImageLength\
,inst.ImageWidth = self.error()
return
#if the_answer isn't 42 then the file not a tiff image!
#BTW - this IS a Douglas Adams reference.
the_answer = image.read(2)
the_answer = struct.unpack(symbol+'H',the_answer)[0]
#the_answer = int(binascii.hexlify(the_answer)[0:2],16)
if the_answer != 42:
inst.ColorProfile,inst.ColorsPerSample,inst.ImageLength\
,inst.ImageWidth = self.error()
return
#Figure out where the Image File Directory is. It can be
#anywhere in the file believe it or not.
dir_loc = image.read(4)
dir_loc = struct.unpack(symbol+'L',dir_loc)[0]
#goto that section of the file
image.seek(dir_loc)
#figure out how many tags there are
directory_data = image.read(2)
num_entries = struct.unpack(symbol+'H',directory_data)[0]
#loop through the Image File Directory and look for the tags we care about
#Width, Height, SamplesPerPixel, and ColorProfile
for i in range(num_entries):
a_tag = image.read(12)
tag = struct.unpack(symbol+'HHLL',a_tag)
#catch in case the type is SHORT
if tag[1] == 3:
tag = struct.unpack(symbol+'HHLHH',a_tag)
#set the class attributes if the tag is one we care about
if tag[0] == 256:
inst.ImageWidth = tag[3]
if tag[0] == 257:
inst.ImageLength = tag[3]
if tag[0] == 258:
inst.ColorsPerSample = tag[2]
if tag[0] == 34675:
inst.ColorProfile = True
if inst.ColorProfile == True:
icc_loc = tag[3]
icc_length = tag[2]
image.seek(icc_loc)
icc_data = image.read(icc_length)
struct_format = '%s%s%s' % (symbol,icc_length,'s')
icc_string = struct.unpack(struct_format,icc_data)[0]
if "Adobe RGB (1998)" in icc_string:
inst.ColorProfile = "Adobe RGB (1998)"
elif "sRGB IEC61966-2-1" in icc_string:
inst.ColorProfile = "sRGB IEC61966-2-1"
elif "ProPhoto RGB" in icc_string:
inst.ColorProfile = "Kodak ProPhoto RGB"
elif "eciRGB" in icc_string:
inst.ColorProfile = "eciRGB v2"
elif "e\0c\0i\0R\0G\0B\0" in icc_string:
inst.ColorProfile = "eciRGB v4"
else:
inst.ColorProfile = "Other"
else:
inst.ColorProfile = "None"
def error(self):
#This error function just resets all the tiff values
ColorProfile = "None"
ColorsPerSample = -1
ImageLength = -1
ImageWidth = -1
return(ColorProfile,ColorsPerSample,ImageLength,ImageWidth)
class TiffInfo(object):
#This is the interface class. When called
#it instantiates the GetTiffInfo() class which actually
#does all the work.
def __init__(self):
self.ColorProfile = "None"
self.ColorsPerSample = -1
self.ImageLength = -1
self.ImageWidth = -1
tiff = GetTiffInfo()
