Refactor PreProcessor and fix Visualizer denormalization issue.

[samet-akcay]

Description

• Fix Visualizer denormalization issue.

• Refactor PreProcessor to improve the flexibility of getting the transforms without relying on a PreProcessor object.

• Refactor read_image to add flexibility of resizing the image while reading.

• Fixes Allow custom Data Normalization and consider it in Post-processing #512

Changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which refactors the code base)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

• My code follows the pre-commit style and check guidelines of this project.
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes

[ashwinvaidya17]

Thanks I don't have anything to add here

[ashwinvaidya17]

Should we also move this function to data/utils?

[samet-akcay]

i think this is still one of the most important components of pre-processing sub-package. If we move it to data/utils, then pre_processing would become quite a weak package that we could consider removing in the future

[djdameln]

In that case we could ask ourselves if we really need the pre-processing module

[samet-akcay]

yes, that's the question, I think

[samet-akcay]

I'm merging this one, we could discuss this later on

[djdameln]

As discussed in the meeting, we could probably deprecate the PreProcessor class now that it's reduced to a wrapper around the get_transforms function. It would require some changes to the datamodule, so let's address this once the datamodule refactor has been merged.