108-resize

[madil90]

Fixes #108 .

Description

Resize an image (Spatial Scale). Tests coming soon.

Status

Work in progress

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or new feature that would cause existing functionality to change)
• New tests added to cover the changes
• Docstrings/Documentation updated

[madil90]

@wyli Tests will be added to PR soon.

[madil90]

@wyli @ericspod By default, skimage.transform.rotate sets preserve_range to False. What happens is

img = np.arange(48).reshape(3, 4, 4)
res = rotate(img, 180, preserve_range=False)

outputs

[[[4.82469967e-18 4.93311988e-18 5.04154010e-18 5.14996032e-18]
[4.39101880e-18 4.49943902e-18 4.60785923e-18 4.71627945e-18]
[3.95733793e-18 4.06575815e-18 4.17417836e-18 4.28259858e-18]
[3.52365706e-18 3.63207728e-18 3.74049750e-18 3.84891771e-18]]

[[3.08997619e-18 3.19839641e-18 3.30681663e-18 3.41523684e-18]
[2.65629532e-18 2.76471554e-18 2.87313576e-18 2.98155597e-18]
[2.22261445e-18 2.33103467e-18 2.43945489e-18 2.54787511e-18]
[1.78893358e-18 1.89735380e-18 2.00577402e-18 2.11419424e-18]]

[[1.35525272e-18 1.46367293e-18 1.57209315e-18 1.68051337e-18]
[9.21571847e-19 1.02999206e-18 1.13841228e-18 1.24683250e-18]
[4.87890978e-19 5.96311195e-19 7.04731412e-19 8.13151629e-19]
[5.42101086e-20 1.62630326e-19 2.71050543e-19 3.79470760e-19]]]

I think this is misleading behavior. By default preserve_range should be True so

img = np.arange(48).reshape(3, 4, 4)
res = rotate(img, 180, preserve_range=True)

outputs

[[[44. 45. 46. 47.]
[40. 41. 42. 43.]
[36. 37. 38. 39.]
[32. 33. 34. 35.]]

[[28. 29. 30. 31.]
[24. 25. 26. 27.]
[20. 21. 22. 23.]
[16. 17. 18. 19.]]

[[12. 13. 14. 15.]
[ 8. 9. 10. 11.]
[ 4. 5. 6. 7.]
[ 0. 1. 2. 3.]]]

[ericspod]

I think preserve_range should be by default True, that seems like expected behaviour.

[Nic-Ma]

Added comments inline.
Thanks.

[Nic-Ma]

Added comments inline.

[Nic-Ma]

Looks good to me.