fix #290

[paquiteau]

Refs: #290

[paquiteau]

So test are passing with current test value if we set data_range=2.0. However, I proposed that we usedata_range=1.0 (see here) , following the documentation of skimage ¹, and that we update the test values

Footnotes

1. https://scikit-image.org/docs/stable/api/skimage.metrics.html#skimage.metrics.structural_similarity ↩