2679 Add IntensityStats transform to record intensity statistics into meta data

[Nic-Ma]

Fixes #2679 .

Description

This PR added IntensityStats transform to record intensity statistics into meta data for other following transforms to dynamically adjust parameters for every image.

Status

Ready

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.

[Nic-Ma]

I enhanced RandShiftIntensityd transform to leverage the intensity stats at runtime, we can also enhance other intensity transforms later.

Thanks.

[wyli]

Thanks, I put some comments inline

[Nic-Ma]

Hi @wyli ,

Thanks for your review.
I updated the PR according to your comments.
Could you please help review it again?

Thanks in advance.

[wyli]

thanks, would be great to have the pickle example as a unit test, but I think it's beyond this PR.

[Nic-Ma]

Hi @wyli ,

I found an easy way to test the pickle issue, already added the logic in the unit test in the latest commit.
If we have self.test = lambda x: x in the __init__() of transform, it will raise the pickle error.

Thanks.

[Nic-Ma]

/black