Patch all-zero alpha: fallback to full-foreground instead of raising ValueError

app.py

@@ -227,6 +227,23 @@ def load_triposg():
             _ip_path.write_text(_ip_text2)
             print("[load_triposg] Patched image_process.py: empty contours guard")
 
+        # Patch all-zero alpha guard: instead of raising ValueError("input image too small"),
+        # fall back to full-foreground alpha so the pipeline can continue with the whole image.
+        # Happens when RMBG produces a blank mask (e.g. remove_small_objects wipes everything).
+        _ip_text3 = _ip_path.read_text()
+        if "all_zero_alpha_guard" not in _ip_text3:
+            _ip_text3 = _ip_text3.replace(
+                '    if np.all(alpha==0):\n        raise ValueError(f"input image too small")',
+                "    if np.all(alpha==0):  # all_zero_alpha_guard\n"
+                "        h_full, w_full = alpha.shape[:2]\n"
+                "        alpha = np.full((h_full, w_full), 255, dtype=np.uint8)\n"
+                "        alpha_gpu = torch.ones(1, h_full, w_full, dtype=torch.float32,\n"
+                "                              device=rgb_image_gpu.device)\n"
+                "        x, y, w, h = 0, 0, w_full, h_full",
+            )
+            _ip_path.write_text(_ip_text3)
+            print("[load_triposg] Patched image_process.py: all-zero alpha fallback")
+
     # Safety net: patch inference_utils.py to make diso import optional.
     # Even if diso compiled with submodules, guard against any residual link errors.
     _iu_path = triposg_src / "triposg" / "inference_utils.py"