improve the readme.

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

README.md

@@ -1,4 +1,4 @@
-# Image Captioning with BLIP
+# Image Captioning with ClipCap
 
 *author: David Wang*
 
@@ -9,7 +9,7 @@
 
 ## Description
 
-This operator generates the caption with [BLIP](https://arxiv.org/abs/2201.12086) which describes the content of the given image. This is an adaptation from [salesforce/BLIP](https://github.com/salesforce/BLIP).
+This operator generates the caption with [ClipCap](https://arxiv.org/abs/2111.09734) which describes the content of the given image. ClipCap uses CLIP encoding as a prefix to the caption, by employing a simple mapping network, and then fine-tunes a language model to generate the image captions. This is an adaptation from [rmokady/CLIP_prefix_caption](https://github.com/rmokady/CLIP_prefix_caption).
 
 
 <br />
@@ -17,17 +17,16 @@ This operator generates the caption with [BLIP](https://arxiv.org/abs/2201.12086
 
 ## Code Example
 
-Load an image from path './animals.jpg' to generate the caption. 
+Load an image from path './hulk.jpg' to generate the caption. 
 
  *Write the pipeline in simplified style*:
 
 ```python
 import towhee
 
-towhee.glob('./animals.jpg') \
+towhee.glob('./hulk.jpg') \
       .image_decode() \
-      .image_captioning.blip(model_name='blip_base') \
-      .select() \
+      .image_captioning.clipcap(model_name='clipcap_coco') \
       .show()
 ```
 <img src="./cap.png" alt="result1" style="height:20px;"/>
@@ -37,9 +36,9 @@ towhee.glob('./animals.jpg') \
 ```python
 import towhee
 
-towhee.glob['path']('./animals.jpg') \
+towhee.glob['path']('./hulk.jpg') \
       .image_decode['path', 'img']() \
-      .image_captioning.blip['img', 'text'](model_name='blip_base') \
+      .image_captioning.clipcap['img', 'text'](model_name='clipcap_coco') \
       .select['img', 'text']() \
       .show()
 ```
@@ -54,14 +53,15 @@ towhee.glob['path']('./animals.jpg') \
 
 Create the operator via the following factory method
 
-***blip(model_name)***
+***clipcap(model_name)***
 
 **Parameters:**
 
 ​   ***model_name:*** *str*
 
-​   The model name of BLIP. Supported model names: 
-- blip_base     
+​   The model name of ClipCap. Supported model names: 
+- clipcap_coco    
+- clipcap_conceptual     
 
 <br />
 
@@ -74,7 +74,7 @@ An image-text embedding operator takes a [towhee image](link/to/towhee/image/api
 
 **Parameters:**
 
-​	***data:*** *towhee.types.Image (a sub-class of numpy.ndarray)*  or *str*
+​	***data:*** *towhee.types.Image (a sub-class of numpy.ndarray)* 
 
 ​  The image to generate embedding.