python读取和写入EXIF信息

gaofeng0210

什么是EXIF信息呢？

百度百科：Exif是一种图象文件格式，它的数据存储与JPEG格式是完全相同的。实际上Exif格式就是在JPEG格式头部插入了数码照片的信息，包括拍摄时的光圈、快门、白平衡、ISO、焦距、日期时间等各种和拍摄条件以及相机品牌、型号、色彩编码、拍摄时录制的声音以及全球定位系统（GPS）、缩略图等。所有的JPEG文件以字符串“0xFFD8”开头，并以字符串“0xFFD9”结束。文件头中有一系列“0xFF??”格式的字符串，称为“标识”，用来标记JPEG文件的信息段。“0xFFD8”表示图像信息开始，“0xFFD9”表示图像信息结束，这两个标识后面没有信息，而其它标识紧跟一些信息字符。0xFFE0
— 0xFFEF之间的标识符称为“应用标记”，没有被常规JPEG文件利用，Exif正是利用这些信息串记录拍摄信息的。

逛摄影论坛时经常会看到，照片的底部包含很多其他信息，如：曝光度，光圈，焦距，快门，机身等等，这些信息就是EXIF信息，摄影爱好者可以参考这些信息提高自己的摄影技术。本文主要涉及的是如何把信息隐藏到图片中，比如一个电影地址。

首先实现一个最简单的方式，把信息直接添加到图片的头部或者尾部，直接添加到头部由于破坏了图片的数据，所以头部会出现一块黑色的区域比较明显，所以别人一下子就看出来了，效果最差。添加到尾部只是简单的增加了图片的大小，图片的数据区域并没有改变，所以如果信息量不是很大，基本是看不出来的，缺点是传到其他网站时容易被裁剪掉。下面的代码实现了把种子隐藏到图片尾部的1024字节区域。

import sys  
def add_info(origin_file, data_file, output_file):  
container = open(origin_file, "rb").read()  
data = open(data_file, "rb").read()  
f = open(output_file, "wb")  
f.write(container)  
if len(data) <= 1024:  
data = '%s%s' %(data,' '*(1024 - len(data)))  
else:  
raise Exception("flag data too long")  
f.write(data)  
f.close()  
def read_info(filename):  
container = open(filename,"r").read()  
print container[len(container) - 1024:len(container)].rstrip()  
if "__main__" == __name__:  
try:  
if len(sys.argv) == 4:  
add_info(sys.argv[1], sys.argv[2], sys.argv[3])  
read_info(sys.argv[3])  
else :   
print "arguments error"
except Exception,err :  
print err
2. 接下来这种方式是把信息写到exif信息中，操作起来比较麻烦，也存在被裁剪的风险。但比上面风险要小很多，一般的网站不会清除图片的exif信息。网上有很多读取EXIF信息的demo，但是写入EXIF信息的比较少，很多人推荐使用pyexif2，但是这个源码安装和配置相当麻烦，直接pass。我需要的是一个文件就能搞定读和写的库，找了半天终于发现了pexif，操作起来十分方便。废话少说，直接贴代码。我添加了set_copyright和read_copyright函数，把电影地址信息添加到Copyright这个标识上，并尝试读取出来。这样就可以非常方便的实现在后台上传图片的时候把电影信息添加到图片里了。#coding=utf-8  
"""
pexif is a module which allows you to view and modify meta-data in
JPEG/JFIF/EXIF files.
The main way to use this is to create an instance of the JpegFile class.
This should be done using one of the static factory methods fromFile,
fromString or fromFd.
After manipulating the object you can then write it out using one of the
writeFile, writeString or writeFd methods.
The get_exif() method on JpegFile returns the ExifSegment if one exists.
Example:
jpeg = pexif.JpegFile.fromFile("foo.jpg")
exif = jpeg.get_exif()
....
jpeg.writeFile("new.jpg")
For photos that don't currently have an exef segment you can specify
an argument which will create the exef segment if it doesn't exist.
Example:
jpeg = pexif.JpegFile.fromFile("foo.jpg")
exif = jpeg.get_exif(create=True)
....
jpeg.writeFile("new.jpg")
The JpegFile class handles file that are formatted in something
approach the JPEG specification (ISO/IEC 10918-1) Annex B 'Compressed
Data Formats', and JFIF and EXIF standard.
a JPEG file is made of a series of segments followed by the image
data. In particular it should look something like:
[ SOI | <arbitrary segments> | SOS | image data | EOI ]
So, the library expects a Start-of-Image marker, followed
by an arbitrary number of segment (assuming that a segment
has the format:
[ <0xFF> <segment-id> <size-byte0> <size-byte1> <data> ]
and that there are no gaps between segments.
The last segment must be the Start-of-Scan header, and the library
assumes that following Start-of-Scan comes the image data, finally
followed by the End-of-Image marker.
This is probably not sufficient to handle arbitrary files conforming
to the JPEG specs, but it should handle files that conform to
JFIF or EXIF, as well as files that conform to neither but
have both JFIF and EXIF application segment (which is the majority
of files in existence!).  
When writing out files all segment will be written out in the order
in which they were read. Any 'unknown' segment will be written out
as is. Note: This may or may not corrupt the data. If the segment
format relies on absolute references then this library may still
corrupt that segment!
Can have a JpegFile in two modes: Read Only and Read Write.
Read Only mode: trying to access missing elements will result in
an AttributeError.
Read Write mode: trying to access missing elements will automatically
create them.
E.g:  
img.exif.primary.<tagname>
.geo
.interop
.exif.<tagname>
.exif.makernote.<tagname>
.thumbnail
img.flashpix.<...>
img.jfif.<tagname>
img.xmp
E.g:  
try:
print img.exif.tiff.exif.FocalLength
except AttributeError:
print "No Focal Length data"
"""
import StringIO  
import sys  
from struct import unpack, pack  
MAX_HEADER_SIZE = 64 * 1024
DELIM = 0xff
EOI = 0xd9
SOI_MARKER = chr(DELIM) + '\xd8'
EOI_MARKER = chr(DELIM) + '\xd9'
EXIF_OFFSET = 0x8769
GPSIFD = 0x8825
TIFF_OFFSET = 6
TIFF_TAG = 0x2a
DEBUG = 0
def debug(*debug_string):  
"""Used for print style debugging. Enable by setting the global
DEBUG to 1."""
if DEBUG:  
for each in debug_string:  
print each,  
print
class DefaultSegment:  
"""DefaultSegment represents a particluar segment of a JPEG file.
This class is instantiated by JpegFile when parsing Jpeg files
and is not intended to be used directly by the programmer. This
base class is used as a default which doesn't know about the internal
structure of the segment. Other classes subclass this to provide
extra information about a particular segment.
"""
def __init__(self, marker, fd, data, mode):  
"""The constructor for DefaultSegment takes the marker which
identifies the segments, a file object which is currently positioned
at the end of the segment. This allows any subclasses to potentially
extract extra data from the stream. Data contains the contents of the
segment."""
self.marker = marker  
self.data = data  
self.mode = mode  
self.fd = fd  
assert mode in ["rw", "ro"]  
if not self.data is None:  
self.parse_data(data)  
class InvalidSegment(Exception):  
"""This exception may be raised by sub-classes in cases when they
can't correctly identify the segment."""
pass
def write(self, fd):  
"""This method is called by JpegFile when writing out the file. It
must write out any data in the segment. This shouldn't in general be
overloaded by subclasses, they should instead override the get_data()
method."""
fd.write('\xff')  
fd.write(pack('B', self.marker))  
data = self.get_data()  
fd.write(pack('>H', len(data) + 2))  
fd.write(data)  
def get_data(self):  
"""This method is called by write to generate the data for this segment.
It should be overloaded by subclasses."""
return self.data  
def parse_data(self, data):  
"""This method is called be init to parse any data for the segment. It
should be overloaded by subclasses rather than overloading __init__"""
pass
def dump(self, fd):  
"""This is called by JpegFile.dump() to output a human readable
representation of the segment. Subclasses should overload this to provide
extra information."""
print >> fd, " Section: [%5s] Size: %6d" % \  
(jpeg_markers[self.marker][0], len(self.data))  
class StartOfScanSegment(DefaultSegment):  
"""The StartOfScan segment needs to be treated specially as the actual
image data directly follows this segment, and that data is not included
in the size as reported in the segment header. This instances of this class
are created by JpegFile and it should not be subclassed.
"""
def __init__(self, marker, fd, data, mode):  
DefaultSegment.__init__(self, marker, fd, data, mode)  
# For SOS we also pull out the actual data  
img_data = fd.read()  
# -2 accounts for the EOI marker at the end of the file  
self.img_data = img_data[:-2]  
fd.seek(-2, 1)  
def write(self, fd):  
"""Write segment data to a given file object"""
DefaultSegment.write(self, fd)  
fd.write(self.img_data)  
def dump(self, fd):  
"""Dump as ascii readable data to a given file object"""
print >> fd, " Section: [  SOS] Size: %6d Image data size: %6d" % \  
(len(self.data), len(self.img_data))  
class ExifType:  
"""The ExifType class encapsulates the data types used
in the Exif spec. These should really be called TIFF types
probably. This could be replaced by named tuples in python 2.6."""
lookup = {}  
def __init__(self, type_id, name, size):  
"""Create an ExifType with a given name, size and type_id"""
self.id = type_id  
self.name = name  
self.size = size  
ExifType.lookup[type_id] = self
BYTE = ExifType(1, "byte", 1).id
ASCII = ExifType(2, "ascii", 1).id
SHORT = ExifType(3, "short", 2).id
LONG = ExifType(4, "long", 4).id
RATIONAL = ExifType(5, "rational", 8).id
UNDEFINED = ExifType(7, "undefined", 1).id
SLONG = ExifType(9, "slong", 4).id
SRATIONAL = ExifType(10, "srational", 8).id
def exif_type_size(exif_type):  
"""Return the size of a type"""
return ExifType.lookup.get(exif_type).size  
class Rational:  
"""A simple fraction class. Python 2.6 could use the inbuilt Fraction class."""
def __init__(self, num, den):  
"""Create a number fraction num/den."""
self.num = num  
self.den = den  
def __repr__(self):  
"""Return a string representation of the fraction."""
return "%s / %s" % (self.num, self.den)  
def as_tuple(self):  
"""Return the fraction a numerator, denominator tuple."""
return (self.num, self.den)  
class IfdData:  
"""Base class for IFD"""
name = "Generic Ifd"
tags = {}  
embedded_tags = {}  
def special_handler(self, tag, data):  
"""special_handler method can be over-ridden by subclasses
to specially handle the conversion of tags from raw format
into Python data types."""
pass
def ifd_handler(self, data):  
"""ifd_handler method can be over-ridden by subclasses to
specially handle conversion of the Ifd as a whole into a
suitable python representation."""
pass
def extra_ifd_data(self, offset):  
"""extra_ifd_data method can be over-ridden by subclasses
to specially handle conversion of the Python Ifd representation
back into a byte stream."""
return ""  
def has_key(self, key):  
return self[key] != None
def __setattr__(self, name, value):  
for key, entry in self.tags.items():  
if entry[1] == name:  
self[key] = value  
self.__dict__[name] = value  
def __delattr__(self, name):  
for key, entry in self.tags.items():  
if entry[1] == name:  
del self[key]  
del self.__dict__[name]  
def __getattr__(self, name):  
for key, entry in self.tags.items():  
if entry[1] == name:  
x = self[key]  
if x is None:  
raise AttributeError  
return x  
for key, entry in self.embedded_tags.items():  
if entry[0] == name:  
if self.has_key(key):  
return self[key]  
else:  
if self.mode == "rw":  
new = entry[1](self.e, 0, "rw", self.exif_file)  
self[key] = new  
return new  
else:  
raise AttributeError  
raise AttributeError, "%s not found.. %s" % (name, self.embedded_tags)  
def __getitem__(self, key):  
if type(key) == type(""):  
try:  
return self.__getattr__(key)  
except AttributeError:  
return None
for entry in self.entries:  
if key == entry[0]:  
if entry[1] == ASCII and not entry[2] is None:  
return entry[2].strip('\0')  
else:  
return entry[2]  
return None
def __delitem__(self, key):  
if type(key) == type(""):  
try:  
return self.__delattr__(key)  
except AttributeError:  
return None
for entry in self.entries:  
if key == entry[0]:  
self.entries.remove(entry)  
def __setitem__(self, key, value):  
if type(key) == type(""):  
return self.__setattr__(key, value)  
found = 0
if len(self.tags[key]) < 3:  
raise "Error: Tags aren't set up correctly, should have tag type."
if self.tags[key][2] == ASCII:  
if not value is None and not value.endswith('\0'):  
value = value + '\0'
for i in range(len(self.entries)):  
if key == self.entries[0]:  
found = 1
entry = list(self.entries)  
if value is None:  
del self.entries  
else:  
entry[2] = value  
self.entries = tuple(entry)  
break
if not found:  
# Find type...  
# Not quite enough yet...  
self.entries.append((key, self.tags[key][2], value))  
return
def __init__(self, e, offset, exif_file, mode, data = None):  
self.exif_file = exif_file  
self.mode = mode  
self.e = e  
self.entries = []  
if data is None:  
return
num_entries = unpack(e + 'H', data[offset:offset+2])[0]  
next = unpack(e + "I", data[offset+2+12*num_entries:  
offset+2+12*num_entries+4])[0]  
debug("OFFSET %s - %s" % (offset, next))  
for i in range(num_entries):  
start = (i * 12) + 2 + offset  
debug("START: ", start)  
entry = unpack(e + "HHII", data[start:start+12])  
tag, exif_type, components, the_data = entry  
debug("%s %s %s %s %s" % (hex(tag), exif_type,  
exif_type_size(exif_type), components,  
the_data))  
byte_size = exif_type_size(exif_type) * components  
if tag in self.embedded_tags:  
actual_data = self.embedded_tags[tag][1](e, the_data,  
exif_file, self.mode, data)  
else:  
if byte_size > 4:  
debug(" ...offset %s" % the_data)  
the_data = data[the_data:the_data+byte_size]  
else:  
the_data = data[start+8:start+8+byte_size]  
if exif_type == BYTE or exif_type == UNDEFINED:  
actual_data = list(the_data)  
elif exif_type == ASCII:  
if the_data[-1] != '\0':  
actual_data = the_data + '\0'
#raise JpegFile.InvalidFile("ASCII tag '%s' not   
# NULL-terminated: %s [%s]" % (self.tags.get(tag,   
# (hex(tag), 0))[0], the_data, map(ord, the_data)))  
#print "ASCII tag '%s' not NULL-terminated:   
# %s [%s]" % (self.tags.get(tag, (hex(tag), 0))[0],   
# the_data, map(ord, the_data))  
actual_data = the_data  
elif exif_type == SHORT:  
actual_data = list(unpack(e + ("H" * components), the_data))  
elif exif_type == LONG:  
actual_data = list(unpack(e + ("I" * components), the_data))  
elif exif_type == SLONG:  
actual_data = list(unpack(e + ("i" * components), the_data))  
elif exif_type == RATIONAL or exif_type == SRATIONAL:  
if exif_type == RATIONAL: t = "II"
else: t = "ii"
actual_data = []  
for i in range(components):  
actual_data.append(Rational(*unpack(e + t,  
the_data[i*8:  
i*8+8])))  
else:  
raise "Can't handle this"
if (byte_size > 4):  
debug("%s" % actual_data)  
self.special_handler(tag, actual_data)  
entry = (tag, exif_type, actual_data)  
self.entries.append(entry)  
debug("%-40s %-10s %6d %s" % (self.tags.get(tag, (hex(tag), 0))[0],  
ExifType.lookup[exif_type],  
components, actual_data))  
self.ifd_handler(data)  
def isifd(self, other):  
"""Return true if other is an IFD"""
return issubclass(other.__class__, IfdData)  
def getdata(self, e, offset, last = 0):  
data_offset = offset+2+len(self.entries)*12+4
output_data = ""  
out_entries = []  
# Add any specifc data for the particular type  
extra_data = self.extra_ifd_data(data_offset)  
data_offset += len(extra_data)  
output_data += extra_data  
for tag, exif_type, the_data in self.entries:  
magic_type = exif_type  
if (self.isifd(the_data)):  
debug("-> Magic..")  
sub_data, next_offset = the_data.getdata(e, data_offset, 1)  
the_data = [data_offset]  
debug("<- Magic", next_offset, data_offset, len(sub_data),  
data_offset + len(sub_data))  
data_offset += len(sub_data)  
assert(next_offset == data_offset)  
output_data += sub_data  
magic_type = exif_type  
if exif_type != 4:  
magic_components = len(sub_data)  
else:  
magic_components = 1
exif_type = 4 # LONG  
byte_size = 4
components = 1
else:  
magic_components = components = len(the_data)  
byte_size = exif_type_size(exif_type) * components  
if exif_type == BYTE or exif_type == UNDEFINED:  
actual_data = "".join(the_data)  
elif exif_type == ASCII:  
actual_data = the_data   
elif exif_type == SHORT:  
actual_data = pack(e + ("H" * components), *the_data)  
elif exif_type == LONG:  
actual_data = pack(e + ("I" * components), *the_data)  
elif exif_type == SLONG:  
actual_data = pack(e + ("i" * components), *the_data)  
elif exif_type == RATIONAL or exif_type == SRATIONAL:  
if exif_type == RATIONAL: t = "II"
else: t = "ii"
actual_data = ""  
for i in range(components):  
actual_data += pack(e + t, *the_data.as_tuple())  
else:  
raise "Can't handle this", exif_type  
if (byte_size) > 4:  
output_data += actual_data  
actual_data = pack(e + "I", data_offset)   
data_offset += byte_size  
else:  
actual_data = actual_data + '\0' * (4 - len(actual_data))  
out_entries.append((tag, magic_type,  
magic_components, actual_data))  
data = pack(e + 'H', len(self.entries))  
for entry in out_entries:  
data += pack(self.e + "HHI", *entry[:3])  
data += entry[3]  
next_offset = data_offset  
if last:  
data += pack(self.e + "I", 0)  
else:  
data += pack(self.e + "I", next_offset)  
data += output_data  
assert (next_offset == offset+len(data))  
return data, next_offset  
def dump(self, f, indent = ""):  
"""Dump the IFD file"""
print >> f, indent + "<--- %s start --->" % self.name  
for entry in self.entries:  
tag, exif_type, data = entry  
if exif_type == ASCII:  
data = data.strip('\0')  
if (self.isifd(data)):  
data.dump(f, indent + "    ")  
else:  
if data and len(data) == 1:  
data = data[0]  
print >> f, indent + "  %-40s %s" % \  
(self.tags.get(tag, (hex(tag), 0))[0], data)  
print >> f, indent + "<--- %s end --->" % self.name  
class IfdInterop(IfdData):  
name = "Interop"
tags = {  
# Interop stuff  
0x0001: ("Interoperability index", "InteroperabilityIndex"),  
0x0002: ("Interoperability version", "InteroperabilityVersion"),  
0x1000: ("Related image file format", "RelatedImageFileFormat"),  
0x1001: ("Related image file width", "RelatedImageFileWidth"),  
0x1002: ("Related image file length", "RelatedImageFileLength"),  
}  
class CanonIFD(IfdData):  
tags = {  
0x0006: ("Image Type", "ImageType"),  
0x0007: ("Firmware Revision", "FirmwareRevision"),  
0x0008: ("Image Number", "ImageNumber"),  
0x0009: ("Owner Name", "OwnerName"),  
0x000c: ("Camera serial number", "SerialNumber"),  
0x000f: ("Customer functions", "CustomerFunctions")  
}  
name = "Canon"
class FujiIFD(IfdData):  
tags = {  
0x0000: ("Note version", "NoteVersion"),  
0x1000: ("Quality", "Quality"),  
0x1001: ("Sharpness", "Sharpness"),  
0x1002: ("White balance", "WhiteBalance"),  
0x1003: ("Color", "Color"),  
0x1004: ("Tone", "Tone"),  
0x1010: ("Flash mode", "FlashMode"),  
0x1011: ("Flash strength", "FlashStrength"),  
0x1020: ("Macro", "Macro"),  
0x1021: ("Focus mode", "FocusMode"),  
0x1030: ("Slow sync", "SlowSync"),  
0x1031: ("Picture mode", "PictureMode"),  
0x1100: ("Motor or bracket", "MotorOrBracket"),  
0x1101: ("Sequence number", "SequenceNumber"),  
0x1210: ("FinePix Color", "FinePixColor"),  
0x1300: ("Blur warning", "BlurWarning"),  
0x1301: ("Focus warning", "FocusWarning"),  
0x1302: ("AE warning", "AEWarning")  
}  
name = "FujiFilm"
def getdata(self, e, offset, last = 0):  
pre_data = "FUJIFILM"
pre_data += pack("<I", 12)  
data, next_offset = IfdData.getdata(self, e, 12, last)  
return pre_data + data, next_offset + offset  
def ifd_maker_note(e, offset, exif_file, mode, data):  
"""Factory function for creating MakeNote entries"""
if exif_file.make == "Canon":  
# Canon maker note appears to always be in Little-Endian  
return CanonIFD('<', offset, exif_file, mode, data)  
elif exif_file.make == "FUJIFILM":  
# The FujiFILM maker note is special.  
# See http://www.ozhiker.com/electronics/pjmt/jpeg_info/fujifilm_mn.html  
# First it has an extra header  
header = data[offset:offset+8]  
# Which should be FUJIFILM  
if header != "FUJIFILM":  
raise JpegFile.InvalidFile("This is FujiFilm JPEG. " \  
"Expecting a makernote header "\  
"<FUJIFILM>. Got <%s>." % header)  
# The it has its own offset  
ifd_offset = unpack("<I", data[offset+8:offset+12])[0]  
# and it is always litte-endian  
e = "<"
# and the data is referenced from the start the Ifd data, not the  
# TIFF file.  
ifd_data = data[offset:]  
return FujiIFD(e, ifd_offset, exif_file, mode, ifd_data)  
else:  
raise JpegFile.InvalidFile("Unknown maker: %s. Can't "\  
"currently handle this." % exif_file.make)  
class IfdGPS(IfdData):  
name = "GPS"
tags = {  
0x0: ("GPS tag version", "GPSVersionID", BYTE, 4),  
0x1: ("North or South Latitude", "GPSLatitudeRef", ASCII, 2),  
0x2: ("Latitude", "GPSLatitude", RATIONAL, 3),  
0x3: ("East or West Longitude", "GPSLongitudeRef", ASCII, 2),  
0x4: ("Longitude", "GPSLongitude", RATIONAL, 3),  
0x5: ("Altitude reference", "GPSAltitudeRef", BYTE, 1),  
0x6: ("Altitude", "GPSAltitude", RATIONAL, 1)  
}  
def __init__(self, e, offset, exif_file, mode, data = None):  
IfdData.__init__(self, e, offset, exif_file, mode, data)  
if data is None:  
self.GPSVersionID = ['\x02', '\x02', '\x00', '\x00']  
class IfdExtendedEXIF(IfdData):  
tags = {  
# Exif IFD Attributes  
# A. Tags relating to version  
0x9000: ("Exif Version", "ExifVersion"),  
0xA000: ("Supported Flashpix version", "FlashpixVersion"),  
# B. Tag relating to Image Data Characteristics  
0xA001: ("Color Space Information", "ColorSpace"),  
# C. Tags relating to Image Configuration  
0x9101: ("Meaning of each component", "ComponentConfiguration"),  
0x9102: ("Image compression mode", "CompressedBitsPerPixel"),  
0xA002: ("Valid image width", "PixelXDimension"),  
0xA003: ("Valid image height", "PixelYDimension"),  
# D. Tags relatin to User informatio  
0x927c: ("Manufacturer notes", "MakerNote"),  
0x9286: ("User comments", "UserComment"),  
# E. Tag relating to related file information  
0xA004: ("Related audio file", "RelatedSoundFile"),  
# F. Tags relating to date and time  
0x9003: ("Date of original data generation", "DateTimeOriginal", ASCII),  
0x9004: ("Date of digital data generation", "DateTimeDigitized", ASCII),  
0x9290: ("DateTime subseconds", "SubSecTime"),  
0x9291: ("DateTime original subseconds", "SubSecTimeOriginal"),  
0x9292: ("DateTime digitized subseconds", "SubSecTimeDigitized"),  
# G. Tags relating to Picture taking conditions  
0x829a: ("Exposure Time", "ExposureTime"),  
0x829d: ("F Number", "FNumber"),  
0x8822: ("Exposure Program", "ExposureProgram"),      
0x8824: ("Spectral Sensitivity", "SpectralSensitivity"),  
0x8827: ("ISO Speed Rating", "ISOSpeedRatings"),  
0x8829: ("Optoelectric conversion factor", "OECF"),  
0x9201: ("Shutter speed", "ShutterSpeedValue"),  
0x9202: ("Aperture", "ApertureValue"),  
0x9203: ("Brightness", "BrightnessValue"),  
0x9204: ("Exposure bias", "ExposureBiasValue"),  
0x9205: ("Maximum lens apeture", "MaxApertureValue"),  
0x9206: ("Subject Distance", "SubjectDistance"),  
0x9207: ("Metering mode", "MeteringMode"),  
0x9208: ("Light mode", "LightSource"),  
0x9209: ("Flash", "Flash"),  
0x920a: ("Lens focal length", "FocalLength"),  
0x9214: ("Subject area", "Subject area"),  
0xa20b: ("Flash energy", "FlashEnergy"),  
0xa20c: ("Spatial frequency results", "SpatialFrquencyResponse"),  
0xa20e: ("Focal plane X resolution", "FocalPlaneXResolution"),  
0xa20f: ("Focal plane Y resolution", "FocalPlaneYResolution"),  
0xa210: ("Focal plane resolution unit", "FocalPlaneResolutionUnit"),  
0xa214: ("Subject location", "SubjectLocation"),  
0xa215: ("Exposure index", "ExposureIndex"),  
0xa217: ("Sensing method", "SensingMethod"),  
0xa300: ("File source", "FileSource"),  
0xa301: ("Scene type", "SceneType"),  
0xa302: ("CFA pattern", "CFAPattern"),  
0xa401: ("Customer image processing", "CustomerRendered"),  
0xa402: ("Exposure mode", "ExposureMode"),  
0xa403: ("White balance", "WhiteBalance"),  
0xa404: ("Digital zoom ratio", "DigitalZoomRation"),  
0xa405: ("Focal length in 35mm film", "FocalLengthIn35mmFilm"),  
0xa406: ("Scene capture type", "SceneCaptureType"),  
0xa407: ("Gain control", "GainControl"),  
0xa40a: ("Sharpness", "Sharpness"),  
0xa40c: ("Subject distance range", "SubjectDistanceRange"),  
# H. Other tags  
0xa420: ("Unique image ID", "ImageUniqueID"),  
}  
embedded_tags = {  
0x927c: ("MakerNote", ifd_maker_note),  
}  
name = "Extended EXIF"
class IfdTIFF(IfdData):  
"""
"""
tags = {  
# Private Tags  
0x8769: ("Exif IFD Pointer", "ExifOffset", LONG),   
0xA005: ("Interoparability IFD Pointer", "InteroparabilityIFD", LONG),  
0x8825: ("GPS Info IFD Pointer", "GPSIFD", LONG),  
# TIFF stuff used by EXIF  
# A. Tags relating to image data structure  
0x100: ("Image width", "ImageWidth", LONG),  
0x101: ("Image height", "ImageHeight", LONG),  
0x102: ("Number of bits per component", "BitsPerSample", SHORT),  
0x103: ("Compression Scheme", "Compression", SHORT),  
0x106: ("Pixel Composition", "PhotometricInterpretion", SHORT),  
0x112: ("Orientation of image", "Orientation", SHORT),  
0x115: ("Number of components", "SamplesPerPixel", SHORT),  
0x11c: ("Image data arrangement", "PlanarConfiguration", SHORT),  
0x212: ("Subsampling ration of Y to C", "YCbCrSubsampling", SHORT),  
0x213: ("Y and C positioning", "YCbCrCoefficients", SHORT),  
0x11a: ("X Resolution", "XResolution", RATIONAL),  
0x11b: ("Y Resolution", "YResolution", RATIONAL),  
0x128: ("Unit of X and Y resolution", "ResolutionUnit", SHORT),  
# B. Tags relating to recording offset  
0x111: ("Image data location", "StripOffsets", LONG),  
0x116: ("Number of rows per strip", "RowsPerStrip", LONG),  
0x117: ("Bytes per compressed strip", "StripByteCounts", LONG),  
0x201: ("Offset to JPEG SOI", "JPEGInterchangeFormat", LONG),  
0x202: ("Bytes of JPEG data", "JPEGInterchangeFormatLength", LONG),  
# C. Tags relating to image data characteristics  
# D. Other tags  
0x132: ("File change data and time", "DateTime", ASCII),  
0x10e: ("Image title", "ImageDescription", ASCII),  
0x10f: ("Camera Make", "Make", ASCII),  
0x110: ("Camera Model", "Model", ASCII),  
0x131: ("Camera Software", "Software", ASCII),  
0x13B: ("Artist", "Artist", ASCII),  
0x8298: ("Copyright holder", "Copyright", ASCII),  
}  
embedded_tags = {  
0xA005: ("Interoperability", IfdInterop),   
EXIF_OFFSET: ("ExtendedEXIF", IfdExtendedEXIF),  
0x8825: ("GPS", IfdGPS),  
}  
name = "TIFF Ifd"
def special_handler(self, tag, data):  
if self.tags[tag][1] == "Make":  
self.exif_file.make = data.strip('\0')  
def new_gps(self):  
if self.has_key(GPSIFD):  
raise ValueError, "Already have a GPS Ifd"  
assert self.mode == "rw"
gps = IfdGPS(self.e, 0, self.mode, self.exif_file)  
self[GPSIFD] = gps  
return gps  
class IfdThumbnail(IfdTIFF):  
name = "Thumbnail"
def ifd_handler(self, data):  
size = None
offset = None
for (tag, exif_type, val) in self.entries:  
if (tag == 0x201):  
offset = val[0]  
if (tag == 0x202):  
size = val[0]  
if size is None or offset is None:  
raise JpegFile.InvalidFile("Thumbnail doesn't have an offset "\  
"and/or size")  
self.jpeg_data = data[offset:offset+size]  
if len(self.jpeg_data) != size:  
raise JpegFile.InvalidFile("Not enough data for JPEG thumbnail."\  
"Wanted: %d got %d" %
(size, len(self.jpeg_data)))  
def extra_ifd_data(self, offset):  
for i in range(len(self.entries)):  
entry = self.entries  
if entry[0] == 0x201:  
# Print found field and updating  
new_entry = (entry[0], entry[1], [offset])  
self.entries = new_entry  
return self.jpeg_data  
class ExifSegment(DefaultSegment):  
"""ExifSegment encapsulates the Exif data stored in a JpegFile. An
ExifSegment contains two Image File Directories (IFDs). One is attribute
information and the other is a thumbnail. This module doesn't provide
any useful functions for manipulating the thumbnail, but does provide
a get_attributes returns an AttributeIfd instances which allows you to
manipulate the attributes in a Jpeg file."""
def __init__(self, marker, fd, data, mode):  
self.ifds = []  
self.e = '<'
self.tiff_endian = 'II'
DefaultSegment.__init__(self, marker, fd, data, mode)  
def parse_data(self, data):  
"""Overloads the DefaultSegment method to parse the data of
this segment. Can raise InvalidFile if we don't get what we expect."""
exif = unpack("6s", data[:6])[0]  
exif = exif.strip('\0')  
if (exif != "Exif"):  
raise self.InvalidSegment("Bad Exif Marker. Got <%s>, "\  
"expecting <Exif>" % exif)  
tiff_data = data[TIFF_OFFSET:]  
data = None # Don't need or want data for now on..  
self.tiff_endian = tiff_data[:2]  
if self.tiff_endian == "II":  
self.e = "<"
elif self.tiff_endian == "MM":  
self.e = ">"
else:  
raise JpegFile.InvalidFile("Bad TIFF endian header. Got <%s>, "
"expecting <II> or <MM>" %  
self.tiff_endian)  
tiff_tag, tiff_offset = unpack(self.e + 'HI', tiff_data[2:8])  
if (tiff_tag != TIFF_TAG):  
raise JpegFile.InvalidFile("Bad TIFF tag. Got <%x>, expecting "\  
"<%x>" % (tiff_tag, TIFF_TAG))  
# Ok, the header parse out OK. Now we parse the IFDs contained in  
# the APP1 header.  
# We use this loop, even though we can really only expect and support  
# two IFDs, the Attribute data and the Thumbnail data  
offset = tiff_offset  
count = 0
while offset:  
count += 1
num_entries = unpack(self.e + 'H', tiff_data[offset:offset+2])[0]  
start = 2 + offset + (num_entries*12)  
if (count == 1):  
ifd = IfdTIFF(self.e, offset, self, self.mode, tiff_data)  
elif (count == 2):  
ifd = IfdThumbnail(self.e, offset, self, self.mode, tiff_data)  
else:  
raise JpegFile.InvalidFile()  
self.ifds.append(ifd)  
# Get next offset  
offset = unpack(self.e + "I", tiff_data[start:start+4])[0]  
def dump(self, fd):  
print >> fd, " Section: [ EXIF] Size: %6d" % \  
(len(self.data))  
for ifd in self.ifds:  
ifd.dump(fd)  
def get_data(self):  
ifds_data = ""  
next_offset = 8
for ifd in self.ifds:  
debug("OUT IFD")  
new_data, next_offset = ifd.getdata(self.e, next_offset,  
ifd == self.ifds[-1])  
ifds_data += new_data  
data = ""  
data += "Exif\0\0"
data += self.tiff_endian  
data += pack(self.e + "HI", 42, 8)  
data += ifds_data  
return data  
def get_primary(self, create=False):  
"""Return the attributes image file descriptor. If it doesn't
exit return None, unless create is True in which case a new
descriptor is created."""
if len(self.ifds) > 0:  
return self.ifds[0]  
else:  
if create:  
assert self.mode == "rw"
new_ifd = IfdTIFF(self.e, None, self, "rw")  
self.ifds.insert(0, new_ifd)  
return new_ifd  
else:  
return None
def _get_property(self):  
if self.mode == "rw":  
return self.get_primary(True)  
else:  
primary = self.get_primary()  
if primary is None:  
raise AttributeError  
return primary  
primary = property(_get_property)  
jpeg_markers = {  
0xc0: ("SOF0", []),  
0xc2: ("SOF2", []),  
0xc4: ("DHT", []),  
0xda: ("SOS", [StartOfScanSegment]),  
0xdb: ("DQT", []),  
0xdd: ("DRI", []),  
0xe0: ("APP0", []),  
0xe1: ("APP1", [ExifSegment]),  
0xe2: ("APP2", []),  
0xe3: ("APP3", []),  
0xe4: ("APP4", []),  
0xe5: ("APP5", []),  
0xe6: ("APP6", []),  
0xe7: ("APP7", []),  
0xe8: ("APP8", []),  
0xe9: ("APP9", []),  
0xea: ("APP10", []),  
0xeb: ("APP11", []),  
0xec: ("APP12", []),  
0xed: ("APP13", []),  
0xee: ("APP14", []),  
0xef: ("APP15", []),  
0xfe: ("COM", []),  
}  
APP1 = 0xe1
class JpegFile:  
"""JpegFile object. You should create this using one of the static methods
fromFile, fromString or fromFd. The JpegFile object allows you to examine and
modify the contents of the file. To write out the data use one of the methods
writeFile, writeString or writeFd. To get an ASCII dump of the data in a file
use the dump method."""
def fromFile(filename, mode="rw"):  
"""Return a new JpegFile object from a given filename."""
return JpegFile(open(filename, "rb"), filename=filename, mode=mode)  
fromFile = staticmethod(fromFile)  
def fromString(str, mode="rw"):  
"""Return a new JpegFile object taking data from a string."""
return JpegFile(StringIO.StringIO(str), "from buffer", mode=mode)  
fromString = staticmethod(fromString)  
def fromFd(fd, mode="rw"):  
"""Return a new JpegFile object taking data from a file object."""
return JpegFile(fd, None, mode=mode)  
fromFd = staticmethod(fromFd)  
class InvalidFile(Exception):  
"""This exception is raised if a given file is not able to be parsed."""
pass
class NoSection(Exception):  
"""This exception is raised if a section is unable to be found."""
pass
def __init__(self, input, filename=None, mode="rw"):  
"""JpegFile Constructor. input is a file object, and filename
is a string used to name the file. (filename is used only for
display functions).  You shouldn't use this function directly,
but rather call one of the static methods fromFile, fromString
or fromFd."""
self.filename = filename  
self.mode = mode  
# input is the file descriptor  
soi_marker = input.read(len(SOI_MARKER))  
# The very first thing should be a start of image marker  
if (soi_marker != SOI_MARKER):  
raise self.InvalidFile("Error reading soi_marker. Got <%s> "\  
"should be <%s>" % (soi_marker, SOI_MARKER))  
# Now go through and find all the blocks of data  
segments = []  
while 1:  
head = input.read(2)  
delim, mark  =  unpack(">BB", head)  
if (delim != DELIM):  
raise self.InvalidFile("Error, expecting delmiter. "\  
"Got <%s> should be <%s>" %
(delim, DELIM))  
if mark == EOI:  
# Hit end of image marker, game-over!  
break
head2 = input.read(2)  
size = unpack(">H", head2)[0]  
data = input.read(size-2)  
possible_segment_classes = jpeg_markers[mark][1] + [DefaultSegment]  
# Try and find a valid segment class to handle  
# this data  
for segment_class in possible_segment_classes:  
try:  
# Note: Segment class may modify the input file   
# descriptor. This is expected.  
attempt = segment_class(mark, input, data, self.mode)  
segments.append(attempt)  
break
except DefaultSegment.InvalidSegment:  
# It wasn't this one so we try the next type.  
# DefaultSegment will always work.  
continue
self._segments = segments  
def writeString(self):  
"""Write the JpegFile out to a string. Returns a string."""
f = StringIO.StringIO()  
self.writeFd(f)  
return f.getvalue()  
def writeFile(self, filename):  
"""Write the JpegFile out to a file named filename."""
output = open(filename, "wb")  
self.writeFd(output)  
def writeFd(self, output):  
"""Write the JpegFile out on the file object output."""
output.write(SOI_MARKER)  
for segment in self._segments:  
segment.write(output)  
output.write(EOI_MARKER)  
def dump(self, f = sys.stdout):  
"""Write out ASCII representation of the file on a given file
object. Output default to stdout."""
print >> f, "<Dump of JPEG %s>" % self.filename  
for segment in self._segments:  
segment.dump(f)  
def get_exif(self, create=False):  
"""get_exif returns a ExifSegment if one exists for this file.
If the file does not have an exif segment and the create is
false, then return None. If create is true, a new exif segment is
added to the file and returned."""
for segment in self._segments:  
if segment.__class__ == ExifSegment:  
return segment  
if create:  
return self.add_exif()  
else:  
return None
def add_exif(self):  
"""add_exif adds a new ExifSegment to a file, and returns
it. When adding an EXIF segment is will add it at the start of
the list of segments."""
assert self.mode == "rw"
new_segment = ExifSegment(APP1, None, None, "rw")  
self._segments.insert(0, new_segment)  
return new_segment  
def _get_exif(self):  
"""Exif Attribute property"""
if self.mode == "rw":  
return self.get_exif(True)  
else:  
exif = self.get_exif(False)  
if exif is None:  
raise AttributeError  
return exif  
exif = property(_get_exif)  
def get_geo(self):  
"""Return a tuple of (latitude, longitude)."""
def convert(x):  
(deg, min, sec) = x  
return (float(deg.num) / deg.den) +  \  
(1/60.0 * float(min.num) / min.den) + \  
(1/3600.0 * float(sec.num) / sec.den)  
if not self.exif.primary.has_key(GPSIFD):  
raise self.NoSection, "File %s doesn't have a GPS section." % \  
self.filename  
gps = self.exif.primary.GPS  
lat = convert(gps.GPSLatitude)  
lng = convert(gps.GPSLongitude)  
if gps.GPSLatitudeRef == "S":  
lat = -lat  
if gps.GPSLongitudeRef == "W":  
lng = -lng  
return lat, lng  
SEC_DEN = 50000000
def _parse(val):  
sign = 1
if val < 0:  
val  = -val  
sign = -1
deg = int(val)  
other = (val - deg) * 60
minutes = int(other)  
secs = (other - minutes) * 60
secs = long(secs * JpegFile.SEC_DEN)  
return (sign, deg, minutes, secs)  
_parse = staticmethod(_parse)  
def set_geo(self, lat, lng):  
"""Set the GeoLocation to a given lat and lng"""
if self.mode != "rw":  
raise RWError  
gps = self.exif.primary.GPS  
sign, deg, min, sec = JpegFile._parse(lat)  
ref = "N"
if sign < 0:  
ref = "S"
gps.GPSLatitudeRef = ref  
gps.GPSLatitude = [Rational(deg, 1), Rational(min, 1),  
Rational(sec, JpegFile.SEC_DEN)]  
sign, deg, min, sec = JpegFile._parse(lng)  
ref = "E"
if sign < 0:  
ref = "W"
gps.GPSLongitudeRef = ref  
gps.GPSLongitude = [Rational(deg, 1), Rational(min, 1),  
Rational(sec, JpegFile.SEC_DEN)]  
def set_copyright(self, copyright):  
"""Set the copyright to a given copyright string"""
if self.mode != "rw":  
raise RWError  
self.exif.primary.Copyright = copyright  
def read_copyright(imgFile):  
jpeg = JpegFile.fromFd(imgFile)  
exif = jpeg.get_exif()  
print exif.get_primary().Copyright.decode("gbk")  
if __name__ == "__main__":  
import StringIO  
import sys  
reload(sys)  
sys.setdefaultencoding('utf-8')  
f = open("test.jpg")  
read_copyright(f)  
f.seek(0)  
jpeg = JpegFile.fromFd(f)  
copyright = u"qvod://fuck小日本".encode("gbk")  
jpeg.set_copyright(copyright)  
buf = StringIO.StringIO()  
jpeg.writeFd(buf)  
buf.seek(0)  
read_copyright(buf)  
f.close()



转载请注明来自：Alex
Zhou，本文链接：http://codingnow.cn/python/612.html