update readme.

Signed-off-by: wxywb <xy.wang@zilliz.com>

README.md

@@ -8,7 +8,7 @@
 
 
 
-## Desription
+## Description
 
 An image crop operator implementation with OpenCV.
 
@@ -20,34 +20,22 @@ An image crop operator implementation with OpenCV.
 
 ## Code Example
 
-Load a image from path './dog.jpg'. 
-
- *Write the pipeline in simplified style:*
+Crop the face from 'einstein.jpg'.
 
 ```python
-import towhee
 
-towhee.glob('./dog.jpg') \
-  .image_decode.cv2() \
-  .show()
-```
-
-*Write a same pipeline with explicit inputs/outputs name specifications:*
-
-```python
 import towhee
 
-towhee.glob['path']('./dog.jpg') \
-  .image_decode.cv2['path', 'img']() \
-  .select['img']() \
+bboxes = towhee.glob['path']('einstein.jpg') \
+  .image_decode['path', 'img']() \
+  .face_detection.retinaface['img', ('box','score')]()\
+  .image_crop[('img', 'box'), 'crop'](clamp = True)\
+  .select['img','crop']()\
   .show()
 ```
 
 
-
-<img src="./show_result.jpg" height="150px"/>
-
-
+<img src="./result.png" height="150px"/>
 
 <br />
 
@@ -57,9 +45,14 @@ towhee.glob['path']('./dog.jpg') \
 
 Create the operator via the following factory method
 
-***image_decode.cv2()***
+***image_crop(clamp = True)***
 
 
+**Parameters:**
+
+**clamp:** *bool*
+
+​ If set True, coordinates of bounding boxes would be clamped into image size.
 
 <br />
 
@@ -67,21 +60,22 @@ Create the operator via the following factory method
 
 ## Interface
 
-An image decode operator takes an image path as input. It decodes the image back to ndarray.
-
+An image crop operator takes an image and bounding boxes as input. It cropes the image into ROIs(region of interest).
 
 
 **Parameters:**
 
-**img**: *str*
+**img:** *towhee.types.Image (a sub-class of numpy.ndarray)* 
 
-​	Image file path.
+​	The image need to be cropped.
 
+**bboxes:** *numpy.ndarray* 
 
+​	The nx4 numpy tensor for n bounding boxes need to crop, each row is formatted as (x1, y1, x2, y2).
 
 **Returns**: *towhee.types.Image (a sub-class of numpy.ndarray)* 
 
-​	The decoded image data as numpy.ndarray.
+​	The cropped image data as numpy.ndarray.