Upload rbga_to_white_bg.py

rbga_to_white_bg.py

@@ -0,0 +1,54 @@
+import torch
+
+class RGBA_White_Background:
+    """
+    Composites an RGBA image over a white background and outputs RGB.
+    Assumes input image in ComfyUI tensor format: float32, 0..1, shape [B,H,W,C].
+    """
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "image": ("IMAGE",),  # Can be RGBA or RGB; if RGB, it passes through
+            }
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    RETURN_NAMES = ("image",)
+    FUNCTION = "composite"
+    CATEGORY = "image"
+
+    def composite(self, image):
+        # image: [B,H,W,C], float32 0..1
+        if not isinstance(image, torch.Tensor):
+            raise TypeError("Expected ComfyUI IMAGE as a torch.Tensor")
+
+        if image.ndim != 4:
+            raise ValueError(f"Expected image shape [B,H,W,C], got {tuple(image.shape)}")
+
+        b, h, w, c = image.shape
+
+        # If already RGB, just ensure it's sane and return.
+        if c == 3:
+            return (image.clamp(0.0, 1.0),)
+
+        if c != 4:
+            raise ValueError(f"Expected 3 (RGB) or 4 (RGBA) channels, got {c}")
+
+        rgb = image[..., :3]
+        a   = image[..., 3:4]  # keep as [B,H,W,1]
+
+        # Composite: out = rgb * a + white * (1-a) ; white=1
+        out = rgb * a + (1.0 - a)
+
+        return (out.clamp(0.0, 1.0),)
+
+
+NODE_CLASS_MAPPINGS = {
+    "RGBA_White_Background": RGBA_White_Background
+}
+
+NODE_DISPLAY_NAME_MAPPINGS = {
+    "RGBA_White_Background": "RGBA to White Background RGB (White Background)"
+}