使用pyexiv2将EXIF信息从一张图片复制到另一张图片

Question

我正在尝试使用pyexiv2将一张图片的EXIF信息复制到它的缩略图上。在寻找解决方案时，我在Stack Overflow上发现了一篇帖子。看起来帖子中使用的API已经过时，最新版本中找不到了。根据最新的文档，我创建了一个这样的函数：

def get_exif(file):
    """
    Retrieves EXIF information from a image
    """
    ret = {}
    metadata = pyexiv2.ImageMetadata(str(file))
    metadata.read()
    info = metadata.exif_keys
    for key in info:
        data = metadata[key]
        ret[key] = data.raw_value
    return ret

def write_exif(originFile, destinationFile, **kwargs):
    """
    This function would write an exif information of an image file to another image file
    """

    exifInformation = get_exif(originFile)
    metadata = pyexiv2.ImageMetadata(str(destinationFile))
    for key, value in exifInformation.iteritems():
        metadata[key] = value

    copyrightName = kwargs.get('copyright', None)
    if copyrightName != None:
        metadata['Exif.Image.Copyright'] = copyrightName

    try:
        metadata.write()
    except:
        return False
    else:
        return True

但是这段代码出现了错误：

Python的参数类型在 _ExifTag._setParentImage(_ExifTag, NoneType)与C++的签名不匹配： _setParentImage(exiv2wrapper::ExifTag {lvalue}, exiv2wrapper::Image {lvalue})

我现在完全不知道哪里出了问题。有人能帮我一下吗？谢谢！

编辑

根据@unutbu的建议，我把get_exif()方法中的data.raw_value改成了data.value，但仍然遇到同样的问题。我在这里贴出更多关于这个错误的信息：

Python argument types in
    _ExifTag._setParentImage(_ExifTag, NoneType)
did not match C++ signature:
    _setParentImage(exiv2wrapper::ExifTag {lvalue}, exiv2wrapper::Image {lvalue})
Request Method: POST
Request URL:    http://localhost:8000/accounts/photography/
Django Version: 1.3.1
Exception Type: ArgumentError
Exception Value:    
Python argument types in
    _ExifTag._setParentImage(_ExifTag, NoneType)
did not match C++ signature:
    _setParentImage(exiv2wrapper::ExifTag {lvalue}, exiv2wrapper::Image {lvalue})
Exception Location: /usr/lib64/python2.7/site-packages/pyexiv2/exif.py in _set_owner, line 107

**Traceback**

/usr/local/lib/python2.7/site-packages/django/core/handlers/base.py in get_response
                        response = callback(request, *callback_args, **callback_kwargs) ...

/usr/local/lib/python2.7/site-packages/django/contrib/auth/decorators.py in _wrapped_view
                return view_func(request, *args, **kwargs) ...

/home/swaroop/public_html/xyz/xyz/apps/photography/views.py in accountsPhotoList
            write_exif(originFile=filePath, destinationFile=output) ...

/home/swaroop/public_html/xyz/xyz/library/imageManipulation.py in write_exif
        metadata[key] = value ...

/usr/lib64/python2.7/site-packages/pyexiv2/metadata.py in __setitem__
            return getattr(self, '_set_%s_tag' % family)(key, tag_or_value) ...

/usr/lib64/python2.7/site-packages/pyexiv2/metadata.py in _set_exif_tag
        tag._set_owner(self) ...

/usr/lib64/python2.7/site-packages/pyexiv2/exif.py in _set_owner
        self._tag._setParentImage(metadata._image) ...

Python Executable:  /usr/bin/python2.7
Python Version: 2.7.2

Answer 1

不要用 metadata['Exif.Image.Copyright'] = copyrightName 这种写法

你应该使用下面的语法：

metadata['Exif.Image.Copyright']  = pyexiv2.ExifTag('Exif.Image.Copyright', copyrightName)

注意：对于 "Exif.Image.Copyright"，copyrightName 的值应该是字符串类型

完整示例：

import pyexiv2
metadata = pyexiv2.ImageMetadata(image_name)
metadata.read() 
metadata.modified = True
metadata.writable = os.access(image_name ,os.W_OK)
metadata['Exif.Image.Copyright']  = pyexiv2.ExifTag('Exif.Image.Copyright', 'copyright@youtext') 
metadata.write()

希望这能对你有所帮助

Answer 2

在pyexiv2的0.3版本中，@user2431382提供的解决方案不能把EXIF标签写入到目标文件和源文件不一样的文件中。下面这个版本对我有效：

m1 = pyexiv2.ImageMetadata( source_filename )
m1.read()
# modify tags ...
# m1['Exif.Image.Key'] = pyexiv2.ExifTag('Exif.Image.Key', 'value')
m1.modified = True # not sure what this is good for
m2 = pyexiv2.metadata.ImageMetadata( destination_filename )
m2.read() # yes, we need to read the old stuff before we can overwrite it
m1.copy( m2 )
m2.write()