add briaai/RMBG-2.0

https://github.com/Sanster/IOPaint/issues/598

iopaint/plugins/briarmbg2.py

@@ -0,0 +1,39 @@
+import numpy as np
+
+
+def create_briarmbg2_session():
+    from transformers import AutoModelForImageSegmentation
+
+    birefnet = AutoModelForImageSegmentation.from_pretrained(
+        "briaai/RMBG-2.0", trust_remote_code=True
+    )
+    return birefnet
+
+
+def briarmbg2_process(bgr_np_image, session, only_mask=False):
+    from torchvision import transforms
+    from PIL import Image
+
+    transform_image = transforms.Compose(
+        [
+            transforms.Resize((1024, 1024)),
+            transforms.ToTensor(),
+            transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225]),
+        ]
+    )
+
+    image = Image.fromarray(bgr_np_image)
+    image_size = image.size
+    input_images = transform_image(image).unsqueeze(0)
+
+    # Prediction
+    preds = session(input_images)[-1].sigmoid().cpu()
+    pred = preds[0].squeeze()
+    pred_pil = transforms.ToPILImage()(pred)
+    mask = pred_pil.resize(image_size)
+
+    if only_mask:
+        return np.array(mask)
+
+    image.putalpha(mask)
+    return np.array(image)