About the EXQUIRES Test Suite

License:BSD 2-Clause License
Authors:Adam Turcotte and Nicolas Robidoux


The EXQUIRES test suite (hereby referred to as EXQUIRES) is an open source framework for assessing the accuracy of image upsampling methods. EXQUIRES can also be used to compare image difference metrics, or to measure the impact of various factors, including test image selection and properties, downsampler choice, resizing ratio, etc.

An upsampler’s performance is based on its ability to reconstruct test images from various reduced versions. The downsampler used to reduce the images has an influence on the re-enlargements, so any number of downsampling methods can be used. The difference between the re-enlargements and the orginal images is determined by using image comparison metrics. When viewing the comparison data, it is possible to aggregate across any combination of test images, downsamplers, and resampling ratios.

EXQUIRES is fully extensible: External applications can be used alongside its own to compute downsampled and upsampled images as well as image difference metrics. The following components of EXQUIRES are configurable:

  • Test Images
  • Resampling Ratios
  • Downsampling Methods
  • Upsampling Methods
  • Difference Metrics

Technical Notes

EXQUIRES is written in Python (requiring version 2.7 or higher) and makes use of several modules, including the following:

  • argparse – command-line argument parsing
  • configobj – reading and writing .ini files
  • curses – displaying progress information
  • fnmatch – handling wildcard characters
  • inspect – listing a class’ methods
  • numpy – applying operations to lists of numbers
  • re – handling arguments with hypenated ranges
  • sqlite3 – database for storing image comparison data
  • subprocess – calling external applications
  • vipsCC – Python interface for VIPS

The following image processing applications are also used:

  • ImageMagick – resampling images
  • VIPS – computing image difference metrics

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