feat(runtime/colormatch): add CUDA support for histogram matching

- Added cupy and cucim to requirements.txt for CUDA operations.
- Updated Runtime44ColorMatch class to handle CUDA devices.
- Included conditional import for match_histograms from cucim.
- Converted tensors to cupy arrays when CUDA is available.
- Removed unnecessary imports and optimized memory usage.

requirements.txt

@@ -4,3 +4,5 @@ Pillow
 numpy
 scikit-image
 opencv-python
+cupy
+cucim

targets/colormatch.py

@@ -1,6 +1,4 @@
 import torch
-import numpy as np
-from skimage.exposure import match_histograms
 
 
 class Runtime44ColorMatch:
@@ -18,7 +16,28 @@ class Runtime44ColorMatch:
     CATEGORY = "image"
 
     def match(self, source: torch.Tensor, target: torch.Tensor):
+        """
+
+        Match the color of the `target` image with the `source` image
+        using the **histogram matching** technique
+
+        Using CuPy (for CUDA) and NumPy (for CPU/Non-CUDA device)
+
+        """
+        is_cuda = torch.cuda.is_available()
+
         target = target.numpy()
         source = source.numpy()
-        matched = match_histograms(target, source, channel_axis=None)
+        if is_cuda:
+            from cucim.skimage.exposure import match_histograms
+            import cupy
+
+            target = cupy.asarray(target)
+            source = cupy.asarray(source)
+        else:
+            from skimage.exposure import match_histograms
+        matched = match_histograms(target, source, channel_axis=-1)
+        matched = cupy.asnumpy(matched) if is_cuda else matched
+        del source
+        del target
         return (torch.from_numpy(matched),)