MS-SSIM Tests. Bug in scale weights check.

[denproc]

Multi Scale SSIM uses scaling weights to compute a score for image pair. The test 1 and test 2, which checks weight format, raises assertion error due to different purpose.

To Reproduce Steps to reproduce the behavior:

1. Run pytest tests/test_ms_ssim.py

2. Observe no error

3. Open test/test_ms_ssim.py

4. Move to line 78

5. See that AssetionError is raised due to missing x variable rather than wrong weight format.

6. Move to line 201

7. See that AssetionError is raised due to missing x variable rather than wrong weight format.

Suggestion

• Fix the test
• Add assertion check, which is missing in MS-SSIM function and class