Library of Congress (LoC) image retrieval script.
The retriever.py script retrieves a single volume of map images from the
Library of Congress. The script relies on retriever_config.yml to provide
configuration values that "point" the script to the target image collection. The script is run from
the terminal and accepts a number of command line arguments:
-
Required: A
< key >(str) value that matches a map key in the companion< retriever_config.yml >file. The< 'key' >arg is used to filter the relevant map data contained in the loaded YAML file. -
Optional: A
< format >(str) value that sets the image extension. Options: 'jpg', 'gif', 'jp2', 'tif'. Default: 'jpg'. -
Optional: A
< size >(int) value that sets the width and height of the image scaled tonpercent of the width and height of the extracted region ('pct:n'). The aspect ratio of the returned image is the same as that of the extracted region. Default value =25. -
Optional: A
< rotation >(int) value that sets the image rotation by degrees (0-360). Default value =0. -
Optional: A
< quality >(str) value that sets the image quality. Options: 'color', 'grey', 'bitonal', 'default'. Default value ='default'. -
Optional: A
< output >(str) value corresponding to the filepath for local storage of the retrieved images. Default value ='./output'.
Once configured, the script retrieves the target images, renames the downloaded files,
stores them locally in the < output > location, and logs the process both via the terminal and
a log file.
{scheme}://{server}{/id_prefix}/{identifier}/{region}/{size}/{rotation}/{quality}.{format}
.jpg (pct:25)
.gif
.jp2
.tif (master)
For addtional information review the LoC's IIIF image retrieval API.
An example LoC Jupyter notebook is available that illustrates image retrieval techniques.
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