feat: Add Mask from ID Node

invokeai/app/invocations/image.py

@@ -967,3 +967,56 @@ class CanvasPasteBackInvocation(BaseInvocation, WithMetadata, WithBoard):
 
         image_dto = context.images.save(image=source_image)
         return ImageOutput.build(image_dto)
+
+
+@invocation(
+    "mask_from_id",
+    title="Mask from ID",
+    tags=["image", "mask", "id"],
+    category="image",
+    version="1.0.0",
+)
+class MaskFromIDInvocation(BaseInvocation, WithMetadata, WithBoard):
+    """Generate a mask for a particular color in an ID Map"""
+
+    image: ImageField = InputField(description="The image to create the mask from")
+    color: ColorField = InputField(description="ID color to mask")
+    threshold: int = InputField(default=100, description="Threshold for color detection")
+    invert: bool = InputField(default=False, description="Whether or not to invert the mask")
+
+    def rgba_to_hex(self, rgba_color: tuple[int, int, int, int]):
+        r, g, b, a = rgba_color
+        hex_code = "#{:02X}{:02X}{:02X}{:02X}".format(r, g, b, int(a * 255))
+        return hex_code
+
+    def id_to_mask(self, id_mask: Image.Image, color: tuple[int, int, int, int], threshold: int = 100):
+        if id_mask.mode != "RGB":
+            id_mask = id_mask.convert("RGB")
+
+        # Can directly just use the tuple but I'll leave this rgba_to_hex here
+        # incase anyone prefers using hex codes directly instead of the color picker
+        hex_color_str = self.rgba_to_hex(color)
+        rgb_color = numpy.array([int(hex_color_str[i : i + 2], 16) for i in (1, 3, 5)])
+
+        # Maybe there's a faster way to calculate this distance but I can't think of any right now.
+        color_distance = numpy.linalg.norm(id_mask - rgb_color, axis=-1)
+
+        # Create a mask based on the threshold and the distance calculated above
+        binary_mask = (color_distance < threshold).astype(numpy.uint8) * 255
+
+        # Convert the mask back to PIL
+        binary_mask_pil = Image.fromarray(binary_mask)
+
+        return binary_mask_pil
+
+    def invoke(self, context: InvocationContext) -> ImageOutput:
+        image = context.images.get_pil(self.image.image_name)
+
+        mask = self.id_to_mask(image, self.color.tuple(), self.threshold)
+
+        if self.invert:
+            mask = ImageOps.invert(mask)
+
+        image_dto = context.images.save(image=mask, image_category=ImageCategory.MASK)
+
+        return ImageOutput.build(image_dto)