Add channel_wise in RandScaleIntensity (#6793)

Part of #6629 .

### Description
Add `channel_wise` in `RandScaleIntensity` and `RandScaleIntensityd`.


### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] 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 --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

---------

Signed-off-by: KumoLiu <[email protected]>

monai/transforms/intensity/array.py

@@ -493,8 +493,8 @@ def __init__(
             fixed_mean: subtract the mean intensity before scaling with `factor`, then add the same value after scaling
                 to ensure that the output has the same mean as the input.
             channel_wise: if True, scale on each channel separately. `preserve_range` and `fixed_mean` are also applied
-            on each channel separately if `channel_wise` is True. Please ensure that the first dimension represents the
-            channel of the image if True.
+                on each channel separately if `channel_wise` is True. Please ensure that the first dimension represents the
+                channel of the image if True.
             dtype: output data type, if None, same as input image. defaults to float32.
         """
         self.factor = factor
@@ -633,12 +633,20 @@ class RandScaleIntensity(RandomizableTransform):
 
     backend = ScaleIntensity.backend
 
-    def __init__(self, factors: tuple[float, float] | float, prob: float = 0.1, dtype: DtypeLike = np.float32) -> None:
+    def __init__(
+        self,
+        factors: tuple[float, float] | float,
+        prob: float = 0.1,
+        channel_wise: bool = False,
+        dtype: DtypeLike = np.float32,
+    ) -> None:
         """
         Args:
             factors: factor range to randomly scale by ``v = v * (1 + factor)``.
                 if single number, factor value is picked from (-factors, factors).
             prob: probability of scale.
+            channel_wise: if True, scale on each channel separately. Please ensure
+                that the first dimension represents the channel of the image if True.
             dtype: output data type, if None, same as input image. defaults to float32.
 
         """
@@ -650,26 +658,39 @@ def __init__(self, factors: tuple[float, float] | float, prob: float = 0.1, dtyp
         else:
             self.factors = (min(factors), max(factors))
         self.factor = self.factors[0]
+        self.channel_wise = channel_wise
         self.dtype = dtype
 
     def randomize(self, data: Any | None = None) -> None:
         super().randomize(None)
         if not self._do_transform:
             return None
-        self.factor = self.R.uniform(low=self.factors[0], high=self.factors[1])
+        if self.channel_wise:
+            self.factor = [self.R.uniform(low=self.factors[0], high=self.factors[1]) for _ in range(data.shape[0])]  # type: ignore
+        else:
+            self.factor = self.R.uniform(low=self.factors[0], high=self.factors[1])
 
     def __call__(self, img: NdarrayOrTensor, randomize: bool = True) -> NdarrayOrTensor:
         """
         Apply the transform to `img`.
         """
         img = convert_to_tensor(img, track_meta=get_track_meta())
         if randomize:
-            self.randomize()
+            self.randomize(img)
 
         if not self._do_transform:
             return convert_data_type(img, dtype=self.dtype)[0]
 
-        return ScaleIntensity(minv=None, maxv=None, factor=self.factor, dtype=self.dtype)(img)
+        ret: NdarrayOrTensor
+        if self.channel_wise:
+            out = []
+            for i, d in enumerate(img):
+                out_channel = ScaleIntensity(minv=None, maxv=None, factor=self.factor[i], dtype=self.dtype)(d)  # type: ignore
+                out.append(out_channel)
+            ret = torch.stack(out)  # type: ignore
+        else:
+            ret = ScaleIntensity(minv=None, maxv=None, factor=self.factor, dtype=self.dtype)(img)
+        return ret
 
 
 class RandBiasField(RandomizableTransform):

monai/transforms/intensity/dictionary.py

@@ -586,6 +586,7 @@ def __init__(
         keys: KeysCollection,
         factors: tuple[float, float] | float,
         prob: float = 0.1,
+        channel_wise: bool = False,
         dtype: DtypeLike = np.float32,
         allow_missing_keys: bool = False,
     ) -> None:
@@ -597,13 +598,15 @@ def __init__(
                 if single number, factor value is picked from (-factors, factors).
             prob: probability of scale.
                 (Default 0.1, with 10% probability it returns a scaled array.)
+            channel_wise: if True, scale on each channel separately. Please ensure
+                that the first dimension represents the channel of the image if True.
             dtype: output data type, if None, same as input image. defaults to float32.
             allow_missing_keys: don't raise exception if key is missing.
 
         """
         MapTransform.__init__(self, keys, allow_missing_keys)
         RandomizableTransform.__init__(self, prob)
-        self.scaler = RandScaleIntensity(factors=factors, dtype=dtype, prob=1.0)
+        self.scaler = RandScaleIntensity(factors=factors, dtype=dtype, prob=1.0, channel_wise=channel_wise)
 
     def set_random_state(
         self, seed: int | None = None, state: np.random.RandomState | None = None
@@ -620,8 +623,15 @@ def __call__(self, data: Mapping[Hashable, NdarrayOrTensor]) -> dict[Hashable, N
                 d[key] = convert_to_tensor(d[key], track_meta=get_track_meta())
             return d
 
+        # expect all the specified keys have same spatial shape and share same random holes
+        first_key: Hashable = self.first_key(d)
+        if first_key == ():
+            for key in self.key_iterator(d):
+                d[key] = convert_to_tensor(d[key], track_meta=get_track_meta())
+            return d
+
         # all the keys share the same random scale factor
-        self.scaler.randomize(None)
+        self.scaler.randomize(d[first_key])
         for key in self.key_iterator(d):
             d[key] = self.scaler(d[key], randomize=False)
         return d

tests/test_rand_scale_intensity.py

@@ -33,6 +33,22 @@ def test_value(self, p):
         expected = p((self.imt * (1 + np.random.uniform(low=-0.5, high=0.5))).astype(np.float32))
         assert_allclose(result, p(expected), rtol=1e-7, atol=0, type_test="tensor")
 
+    @parameterized.expand([[p] for p in TEST_NDARRAYS])
+    def test_channel_wise(self, p):
+        scaler = RandScaleIntensity(factors=0.5, channel_wise=True, prob=1.0)
+        scaler.set_random_state(seed=0)
+        im = p(self.imt)
+        result = scaler(im)
+        np.random.seed(0)
+        # simulate the randomize() of transform
+        np.random.random()
+        channel_num = self.imt.shape[0]
+        factor = [np.random.uniform(low=-0.5, high=0.5) for _ in range(channel_num)]
+        expected = p(
+            np.stack([np.asarray((self.imt[i]) * (1 + factor[i])) for i in range(channel_num)]).astype(np.float32)
+        )
+        assert_allclose(result, expected, atol=0, rtol=1e-5, type_test=False)
+
 
 if __name__ == "__main__":
     unittest.main()

tests/test_rand_scale_intensityd.py

@@ -32,6 +32,22 @@ def test_value(self):
             expected = (self.imt * (1 + np.random.uniform(low=-0.5, high=0.5))).astype(np.float32)
             assert_allclose(result[key], p(expected), type_test="tensor")
 
+    def test_channel_wise(self):
+        key = "img"
+        for p in TEST_NDARRAYS:
+            scaler = RandScaleIntensityd(keys=[key], factors=0.5, prob=1.0, channel_wise=True)
+            scaler.set_random_state(seed=0)
+            result = scaler({key: p(self.imt)})
+            np.random.seed(0)
+            # simulate the randomize function of transform
+            np.random.random()
+            channel_num = self.imt.shape[0]
+            factor = [np.random.uniform(low=-0.5, high=0.5) for _ in range(channel_num)]
+            expected = p(
+                np.stack([np.asarray((self.imt[i]) * (1 + factor[i])) for i in range(channel_num)]).astype(np.float32)
+            )
+            assert_allclose(result[key], p(expected), type_test="tensor")
+
 
 if __name__ == "__main__":
     unittest.main()