Metar
Metar is a library and command line program for reading image metadata.
You can read metadata from JPEG, DNG and TIFF images. Metar understands the standard image metadata formats: XMP, IPTC, Exif, and Tiff tags.
How to Run Metar
You can run metar from the command line to display image metadata. Running metar without any parameters shows how to use it. For example:
metar Show metadata information for the given image(s). Usage: metar [-j] [-v] file [file...] -j --json Output JSON data. -v --version Show the version number. -h --help Show this help. file Image filename to analyze.
You pass an image filename and metar outputs metadata to the screen, for example:
metar testfiles/image.dng ========== ifd1 ========== offset = 8 next = 0 NewSubfileType(254) = [1] ImageWidth(256) = [256] ImageHeight(257) = [171] BitsPerSample(258) = [8, 8, 8] Compression(259) = [1] PhotometricInterpretation(262) = [2] Make(271) = ["Canon"] Model(272) = ["Canon EOS 20D"] ...
Only the first few lines are shown in the example above to save space. For this image there are 291 lines:
metar testfiles/image.dng | wc -l 291
How Use Metar in Python Programs
You can use the metar python module to read image file metadata in your python programs. It contains four public methods: read_metadata_json, read_metadata, key_name, and get_version.
In a python interactive session you can see the methods:
>>> import metar >>> dir(metar) ['__doc__', '__file__', '__name__', '__package__', 'get_version', 'key_name', 'read_metadata', 'read_metadata_json']
The metar module has help documentation in doc strings.
>>> help(metar)
You can determine the metar version number with the get_version function:
>>> metar.get_version() '0.0.4'
You can read the metadata from jpeg and tiff image files using the read_metadata and read_metadata_json functions.
The read_metadata_json function returns the metadata as a JSON string. You can load that into a python dictionary with the json loads function.
>>> filename = "testfiles/IMG_6093.JPG" >>> string = metar.read_metadata_json(filename) >>> import json >>> metadata = json.loads(string)
Then you can extract the metadata you are interested in from the dictionary.
>>> image = metadata['image']
>>> print('width = %s' % image['width'])
width = 3329
>>> print('height = %s' % image['height'])
height = 2219
The read_metadata function returns a more human readable string.
>>> string = metar.read_metadata(filename) >>> print(string) ========== APP0 ========== id = "JFIF" major = 1 minor = 2 units = 1 x = 240 y = 240 ...
More Pages
You can learn how to build, test and install on the development page.
- development -- how to build, test and install
You can learn how metar deals with special images with unknown sections or corrupt files and other details on the details page.
- details -- metadata processing details
You can view the documentation for all the modules and procedures on the index page. This documentation is created from embedded doc comments in the source.
- index -- index to source documentation
Here is the metar module dependencies graph:
