Add support for background components in FrameSliceSegmentationExtrac…

…tor (#378)

* add support for background components in FrameSliceSegmentationExtractor

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* update CHANGELOG.md

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -7,6 +7,7 @@
 ### Fixes
 * Added specific error message for single-frame scanimage data [PR #360](https://github.com/catalystneuro/roiextractors/pull/360)
 * Fixed bug with ScanImage's parse_metadata so that it works properly when hStackManager is disabled [PR #373](https://github.com/catalystneuro/roiextractors/pull/373)
+* Add support for background components in FrameSliceSegmentationExtractor [PR #378](https://github.com/catalystneuro/roiextractors/pull/378)
 
 ### Improvements
 * Removed unnecessary import checks for scipy, h5py, and zarr [PR #364](https://github.com/catalystneuro/roiextractors/pull/364)

src/roiextractors/segmentationextractor.py

@@ -476,6 +476,9 @@ def __init__(
         if hasattr(self._parent_segmentation, "_image_masks"):  # otherwise, do not set attribute at all
             self._image_masks = self._parent_segmentation._image_masks
 
+        if hasattr(self._parent_segmentation, "_background_image_masks"):  # otherwise, do not set attribute at all
+            self._background_image_masks = self._parent_segmentation._background_image_masks
+
         parent_size = self._parent_segmentation.get_num_frames()
         if start_frame is None:
             start_frame = 0
@@ -530,6 +533,9 @@ def get_num_frames(self) -> int:
     def get_num_rois(self) -> int:
         return self._parent_segmentation.get_num_rois()
 
+    def get_num_background_components(self) -> int:
+        return self._parent_segmentation.get_num_background_components()
+
     def get_images_dict(self) -> dict:
         return self._parent_segmentation.get_images_dict()
 
@@ -550,3 +556,6 @@ def get_num_planes(self) -> int:
 
     def get_roi_pixel_masks(self, roi_ids: Optional[ArrayLike] = None) -> List[np.ndarray]:
         return self._parent_segmentation.get_roi_pixel_masks(roi_ids=roi_ids)
+
+    def get_background_pixel_masks(self, background_ids: Optional[ArrayLike] = None) -> List[np.ndarray]:
+        return self._parent_segmentation.get_background_pixel_masks(background_ids=background_ids)