Added histogram widget

negstation/widgets/monochrome_widget.py

@@ -0,0 +1,31 @@
+import dearpygui.dearpygui as dpg
+import numpy as np
+
+from .pipeline_stage_widget import PipelineStageWidget
+
+
+class MonochromeStage(PipelineStageWidget):
+    name = "Monochrome"
+    register = True
+    has_pipeline_in = True
+    has_pipeline_out = True
+
+    def __init__(self, manager, logger):
+        super().__init__(manager, logger, default_stage_out="monochrome")
+
+    def create_pipeline_stage_content(self):
+        dpg.add_text("Converting to grayscale...")
+
+    def on_pipeline_data(self, img):
+        if img is None:
+            return
+        gray = img.copy()
+        rgb = gray[..., :3]
+        alpha = gray[..., 3:] if gray.shape[2] == 4 else np.ones_like(
+            rgb[..., :1])
+
+        luminance = np.dot(rgb, [0.2126, 0.7152, 0.0722])[..., np.newaxis]
+        gray_rgba = np.concatenate(
+            [luminance, luminance, luminance, alpha], axis=-1)
+
+        self.publish_stage(gray_rgba.astype(np.float32))