fix(api): remove black paint detection - just auto-detect pink segments, everything else kept automatically

api/main.py

@@ -335,7 +335,7 @@ def inpaint_multipart(
         log.info("Successfully created black/white mask: %d white pixels (to remove), %d black pixels (to keep)",
                  nonzero, binmask.shape[0] * binmask.shape[1] - nonzero)
     else:
-        mask_rgba = _load_rgba_mask_from_image(m)
+    mask_rgba = _load_rgba_mask_from_image(m)
 
     # When mask_is_painted=true, we create white=remove masks, so invert_mask should be False
     # (white pixels should stay white to indicate removal)
@@ -371,8 +371,10 @@ def remove_pink_segments(
     _: None = Depends(bearer_auth),
 ) -> Dict[str, str]:
     """
-    Simple endpoint: just upload an image with pink/magenta segments you want to remove.
-    The API automatically detects pink areas and removes them, keeping everything else.
+    Simple endpoint: upload an image with pink/magenta segments to remove.
+    - Pink/Magenta segments → automatically removed (white in mask)
+    - Everything else → automatically kept (black in mask)
+    Just paint pink/magenta on areas you want to remove, upload the image, and it works!
     """
     log.info(f"Simple remove-pink: processing image {image.filename}")
     
@@ -380,14 +382,18 @@ def remove_pink_segments(
     img = Image.open(image.file).convert("RGBA")
     img_rgb = cv2.cvtColor(np.array(img), cv2.COLOR_RGBA2RGB)
     
-    # Auto-detect pink/magenta segments
+    # Auto-detect pink/magenta segments to remove
+    # Pink/Magenta → white in mask (remove)
+    # Everything else (natural image colors, including dark areas) → black in mask (keep)
+    
+    # Detect pink/magenta paint (RGB: R>240, G<30, B>240)
     magenta_detected = (
         (img_rgb[:, :, 0] > 240) &  # Red: high
         (img_rgb[:, :, 1] < 30) &   # Green: low
         (img_rgb[:, :, 2] > 240)    # Blue: high
     ).astype(np.uint8) * 255
     
-    # Clean up the mask
+    # Clean up the pink mask
     kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (5, 5))
     binmask = cv2.morphologyEx(magenta_detected, cv2.MORPH_CLOSE, kernel, iterations=2)
     binmask = cv2.morphologyEx(binmask, cv2.MORPH_OPEN, kernel, iterations=1)
@@ -400,7 +406,7 @@ def remove_pink_segments(
         magenta_strict = np.all(img_rgb == [255, 0, 255], axis=2).astype(np.uint8) * 255
         binmask = cv2.morphologyEx(magenta_strict, cv2.MORPH_CLOSE, kernel, iterations=3)
         nonzero = int((binmask > 0).sum())
-        log.info(f"Strict detection: {nonzero} pixels")
+        log.info(f"Strict detection: {nonzero} pink pixels")
     
     if nonzero < 50:
         log.error("No pink segments detected! Returning original image.")
@@ -413,14 +419,17 @@ def remove_pink_segments(
             "error": "No pink/magenta segments detected. Please paint areas to remove with magenta/pink color (RGB 255,0,255)."
         }
     
-    # Create mask: white = pink areas (remove), black = everything else (keep)
+    # Create mask: 
+    # - White = pink areas (remove)
+    # - Black = everything else (keep) - automatically, no black painting needed
     mask_rgba = np.zeros((binmask.shape[0], binmask.shape[1], 4), dtype=np.uint8)
-    mask_rgba[:, :, 0] = binmask  # R
-    mask_rgba[:, :, 1] = binmask  # G
-    mask_rgba[:, :, 2] = binmask  # B
-    mask_rgba[:, :, 3] = 255      # Alpha
+    mask_rgba[:, :, 0] = binmask  # R: white where pink detected
+    mask_rgba[:, :, 1] = binmask  # G: white where pink detected
+    mask_rgba[:, :, 2] = binmask  # B: white where pink detected
+    mask_rgba[:, :, 3] = 255      # Alpha: fully opaque
     
-    log.info(f"Created mask: {nonzero} white pixels (remove), {binmask.shape[0]*binmask.shape[1]-nonzero} black pixels (keep)")
+    total_pixels = binmask.shape[0] * binmask.shape[1]
+    log.info(f"Created mask: {nonzero} white pixels (remove/pink), {total_pixels - nonzero} black pixels (keep - everything else automatically)")
     
     # Process with invert_mask=False because white pixels = remove (standard)
     result = process_inpaint(np.array(img), mask_rgba, invert_mask=False)