diff --git a/cocomltools/coco_ops.py b/cocomltools/coco_ops.py
index d18556a..1bcdb60 100644
--- a/cocomltools/coco_ops.py
+++ b/cocomltools/coco_ops.py
@@ -5,6 +5,11 @@
 from collections import defaultdict
 from PIL import Image
 from pathlib import Path
+import numpy as np
+from tqdm import tqdm
+from concurrent.futures import ThreadPoolExecutor, as_completed
+import asyncio
+import time
 
 
 class CocoOps:
@@ -83,24 +88,47 @@ def _crop_and_save_one_ann(
 
         x1, y1, w, h = ann.bbox
         x2, y2 = x1 + w, y1 + h
-        category_name = self.cat_ids_to_names[ann.category_id]
+        category_name = self.coco.cat_ids_to_names[ann.category_id]
         category_dir = Path(output_dir) / category_name
         category_dir.mkdir(exist_ok=True, parents=True)
         crop_out_file = category_dir / f"{ann.id}.jpg"
         crop = image.crop((x1, y1, x2, y2))
         crop.save(crop_out_file)
 
+    def _crop_one_image(self, elem: Image, images_dir: Path, output_dir: Path):
+        file_image = Path(images_dir) / elem.file_name
+        annotations = self.coco.get_annotation_by_image_id(elem.id)
+        if len(annotations) == 0:  # if no annotations, skip
+            return
+        image = Image.open(file_image).convert("RGB")
+        for ann in annotations:
+            self._crop_and_save_one_ann(image, ann, output_dir)
+
     def crop(
         self,
-        images_dir: str,
-        output_dir: str,
+        images_dir: Path,
+        output_dir: Path,
+        max_workers: int = 1,
     ):
+        if isinstance(images_dir, str):
+            images_dir = Path(images_dir)
+
+        if isinstance(output_dir, str):
+            output_dir = Path(output_dir)
+
+        output_dir.mkdir(parents=True, exist_ok=True)
+
+        start_time = time.time()
+        with ThreadPoolExecutor(max_workers=max_workers) as executor:
 
-        for elem in self.images:
-            file_image = Path(images_dir) / elem.file_name
-            annotations = self.coco.get_annotation_by_image_id(elem.id)
-            if len(annotations) == 0:  # if no annotations, skip
-                continue
-            image = Image.open(file_image).convert("RGB")
-            for ann in annotations:
-                self._crop_and_save_one_ann(image, ann, output_dir)
+            futures = [
+                executor.submit(self._crop_one_image, elem, images_dir, output_dir)
+                for elem in self.coco.images
+            ]
+            for future in as_completed(futures):
+                try:
+                    future.result()
+                except Exception as e:
+                    print(f"Error processing annotation: {e}")
+        elapsed_time = time.time() - start_time
+        print(f"Completed cropping dataset in {elapsed_time:.2f} seconds")
diff --git a/cocomltools/models/base.py b/cocomltools/models/base.py
index 78e630d..9d4c8c3 100644
--- a/cocomltools/models/base.py
+++ b/cocomltools/models/base.py
@@ -16,7 +16,7 @@ class Annotation(BaseModel):
     score: float = Field(default=1.0)
     bbox: List[float]
     segmentation: List[float] | List[List[float]] = Field(default=[])
-    area: int
+    area: float
     iscrowd: int = Field(default=0)
 
 
diff --git a/main_cli.py b/main_cli.py
index 6276d8c..17841a7 100644
--- a/main_cli.py
+++ b/main_cli.py
@@ -54,7 +54,7 @@ def crop_cmd(args):
         Path(args.output_dir) if args.output_dir else images_dir.parent / "cropped"
     )
     output_dir.mkdir(exist_ok=True, parents=True)
-    coco_ops.crop(images_dir, output_dir)
+    coco_ops.crop(images_dir, output_dir, max_workers=args.num_workers)
 
 
 def parse_args():
@@ -96,6 +96,13 @@ def parse_args():
         "--images-dir", required=True, help="Path to coco image files"
     )
     parser_crop.add_argument("--output-dir", required=False, help="Path to output dir")
+    parser_crop.add_argument(
+        "--num-workers",
+        required=False,
+        default=1,
+        type=int,
+        help="number of workers to crop the dataset",
+    )
     args = parser.parse_args()
     return args