Add missing channel_wise parameter to RandScaleIntensityFixedMean by engmohamedsalah · Pull Request #8741 · Project-MONAI/MONAI

engmohamedsalah · 2026-02-14T20:28:48Z

Summary

Adds the channel_wise parameter to RandScaleIntensityFixedMean and RandScaleIntensityFixedMeand, which was documented in docstrings but never implemented.
When channel_wise=True, a separate random scale factor is generated per channel, and preserve_range/fixed_mean are applied per channel — following the existing pattern from RandScaleIntensity.
Fixes docstring indentation for channel_wise in both array and dictionary transforms.

Fixes #8363

Changes

`monai/transforms/intensity/array.py`

Added channel_wise parameter to RandScaleIntensityFixedMean.__init__
Updated randomize() to generate per-channel factors when channel_wise=True
Updated __call__ to apply per-channel scaling with individual random factors

`monai/transforms/intensity/dictionary.py`

Added channel_wise parameter to RandScaleIntensityFixedMeand.__init__
Updated __call__ to pass image data to randomize() (needed for channel count), following the pattern from RandScaleIntensityd

Tests

Added test_channel_wise and test_channel_wise_preserve_range to test_rand_scale_intensity_fixed_mean.py
Added test_channel_wise to test_rand_scale_intensity_fixed_meand.py

Test plan

All existing tests pass (no regressions)
New channel_wise tests pass for both array and dictionary transforms
Verified per-channel mean preservation with fixed_mean=True
Verified preserve_range clipping works per channel

coderabbitai · 2026-02-14T20:29:05Z

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📥 Commits

Reviewing files that changed from the base of the PR and between ae90682 and 3d83082.

📒 Files selected for processing (1)

monai/transforms/intensity/array.py

🚧 Files skipped from review as they are similar to previous changes (1)

monai/transforms/intensity/array.py

📝 Walkthrough

Walkthrough

Adds channel-wise support to RandScaleIntensityFixedMean (array) and its dictionary wrapper. The array transform gains a new channel_wise: bool parameter, stores it, forwards it to the internal scaler, samples per-channel factors when enabled, and applies per-channel scaling by iterating channels and concatenating results while preserving dtype, fixed_mean, and preserve_range semantics. The dictionary transform propagates channel_wise into its internal scaler, changes randomization to self.scaler.randomize(d[first_key]) when keys share the same factor, and adds an early-return path that converts all values to tensors when first_key == (). Tests were added to validate per-channel scaling and preserve_range behavior.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 27.27% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title directly describes the main change: adding a previously missing channel_wise parameter to RandScaleIntensityFixedMean.
Description check	✅ Passed	Description covers all required sections: summary, changes, tests, and test plan. Fixes issue reference included.
Linked Issues check	✅ Passed	PR implements all objectives from `#8363`: adds channel_wise parameter [`#8363`], generates per-channel factors [`#8363`], applies per-channel scaling [`#8363`], ensures fixed_mean and preserve_range work per-channel [`#8363`], follows RandScaleIntensity pattern [`#8363`].
Out of Scope Changes check	✅ Passed	All changes align with `#8363` scope: parameter implementation, per-channel logic, docstring corrections, and corresponding tests.

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…oject-MONAI#8363) The channel_wise parameter was documented in the docstring but not actually accepted by RandScaleIntensityFixedMean or its dictionary variant. This adds the parameter with per-channel random factor generation and scaling, matching the existing pattern in RandScaleIntensity. Also fixes docstring indentation. Signed-off-by: Mohamed Salah <eng.mohamed.tawab@gmail.com>

…ean-8363

ericspod

Hi @engmohamedsalah I made a few comments below but it otherwise looks good to me with a few changes. Thanks!

monai/transforms/intensity/array.py

monai/transforms/intensity/dictionary.py

… simplify loop - Move channel_wise parameter to end of argument list in both array and dictionary variants to preserve positional argument compatibility - Use R.uniform(size=) instead of list comprehension for per-channel factors - Simplify channel-wise __call__ using float() cast, torch.cat, and removing redundant [0] index - Reorder docstrings to match new argument order Signed-off-by: Mohamed Salah <eng.mohamed.tawab@gmail.com>

…ean-8363

…nd cat - Add type: ignore[index] for self.factor[i] since mypy can't narrow the type in the channel_wise branch - Add type: ignore[arg-type] for scale_trans output appended to list - Type out list as list[torch.Tensor] to satisfy torch.cat signature - Follows same pattern as existing RandScaleIntensity (line 738-740) Signed-off-by: Mohamed Salah <eng.mohamed.tawab@gmail.com>

…ean-8363

engmohamedsalah · 2026-03-03T23:39:04Z

@ericspod please check again after apply all your comments

engmohamedsalah requested review from KumoLiu, Nic-Ma and ericspod as code owners February 14, 2026 20:28

engmohamedsalah force-pushed the fix/add-channel-wise-randscaleintensityfixedmean-8363 branch from 738a3f9 to da88dbe Compare February 23, 2026 14:22

engmohamedsalah force-pushed the fix/add-channel-wise-randscaleintensityfixedmean-8363 branch from da88dbe to f996a93 Compare February 23, 2026 15:43

engmohamedsalah added 2 commits February 25, 2026 14:32

Merge branch 'dev' into fix/add-channel-wise-randscaleintensityfixedm…

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…ean-8363

Merge branch 'dev' into fix/add-channel-wise-randscaleintensityfixedm…

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…ean-8363

ericspod requested changes Mar 1, 2026

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engmohamedsalah added 6 commits March 3, 2026 13:51

Merge branch 'dev' into fix/add-channel-wise-randscaleintensityfixedm…

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Merge branch 'dev' into fix/add-channel-wise-randscaleintensityfixedm…

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Merge branch 'dev' into fix/add-channel-wise-randscaleintensityfixedm…

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Merge branch 'dev' into fix/add-channel-wise-randscaleintensityfixedm…

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Add missing channel_wise parameter to RandScaleIntensityFixedMean#8741

Add missing channel_wise parameter to RandScaleIntensityFixedMean#8741
engmohamedsalah wants to merge 9 commits intoProject-MONAI:devfrom
engmohamedsalah:fix/add-channel-wise-randscaleintensityfixedmean-8363

engmohamedsalah commented Feb 14, 2026

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coderabbitai bot commented Feb 14, 2026 •

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engmohamedsalah commented Mar 3, 2026

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engmohamedsalah commented Feb 14, 2026

Summary

Changes

monai/transforms/intensity/array.py

monai/transforms/intensity/dictionary.py

Tests

Test plan

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engmohamedsalah commented Mar 3, 2026

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`monai/transforms/intensity/array.py`

`monai/transforms/intensity/dictionary.py`

coderabbitai bot commented Feb 14, 2026 •

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