Tests for the quality of loaded images are not performed

It would be interesting to perform tests for the quality of loaded images. One possibility is the following:

1. An operator verifies that the images being loaded are OK
2. An histogram of target test images are stored in a file
3. When the tests run, the histogram of the new image is compared with the stored histogram, if they match, the test passes.

This could be done for a reduced number of images per database/dataset to save space.