added invert filter

README.md

@@ -159,6 +159,7 @@ The following filters are currently supported:
 | `bilateral` | Applies a [bilateral filter](https://en.wikipedia.org/wiki/Bilateral_filter), using `d`, `sigma_color` and `sigma_space` parameters. |
 | `motion_blur` | Adds a motion blur to the image or channel. That could be used to make an alpha mask move more slowly |
 | `pixelate` | Pixelates the input. |
+| `invert` | Inverts the input. e.g. `black` to `white` |
 
 Every *filter* may have additional properties. Please refer to the [examples](https://github.com/de-code/layered-vision/tree/develop/example-config) (or come back in the future) for more detailed information.
 

example-config/display-video-bodypix-replace-background-template.yml

@@ -26,6 +26,10 @@ layers:
         internal_resolution: 0.5
         threshold: 0.5
         cache_model_result_secs: 0
+      - id: invert
+        filter: invert
+        channel: alpha
+        enabled: false
       - id: erode
         filter: erode
         channel: alpha
@@ -51,6 +55,10 @@ layers:
         channel: alpha
         frame_count: 3
         decay: 0
+      - id: pixelate
+        filter: pixelate
+        value: 0.1
+        enabled: false
   - id: fg
     enabled: false
     no_source: false

layered_vision/filters/invert.py

@@ -0,0 +1,18 @@
+import logging
+
+import cv2
+
+from layered_vision.utils.image import ImageArray
+from layered_vision.filters.api import AbstractOptionalChannelFilter
+
+
+LOGGER = logging.getLogger(__name__)
+
+
+class InvertFilter(AbstractOptionalChannelFilter):
+    def do_channel_filter(self, image_array: ImageArray) -> ImageArray:
+        LOGGER.debug('invert, image_array dtype: %s', image_array.dtype)
+        return cv2.bitwise_not(image_array)
+
+
+FILTER_CLASS = InvertFilter