Update png and Update README

Signed-off-by: shiyu22 <shiyu.chen@zilliz.com>

README.md

@@ -10,17 +10,17 @@ This Operator generates feature vectors from the pytorch pretrained **Resnet50**
 
 ## Interface
 
-`Class Resnet50ImageEmbedding(Operator)` [source](./resnet50_image_embedding.py)
+`Class Resnet50ImageEmbedding(Operator)` [\[source\]](./resnet50_image_embedding.py)
 
 `__init__(self, model_name: str)`
 
-**param:**
+**params:**
 
 - model_name(str): the model name for embedding, like 'resnet50'.
 
 `__call__(self, img_tensor: torch.Tensor)`
 
-**param:**
+**params:**
 
 - img_tensor(torch.Tensor): the normalized image tensor.
 
@@ -41,11 +41,11 @@ You can get the required python package by [requirements.txt](./requirements.txt
 
 ### How it works
 
-The towhee/resnet50_image_embedding Operator implements the function of image embedding, which can add to the pipeline, for example, it's the key Operator within [image_embedding_resnet50](https://hub.towhee.io/towhee/image-embedding-resnet50) pipeline, and it is the red box in the picture below.
+The `towhee/resnet50-image-embedding` Operator implements the function of image embedding, which can add to the pipeline, for example, it's the key Operator named embedding_model within [image_embedding_resnet50](https://hub.towhee.io/towhee/image-embedding-resnet50) pipeline, and it is the red box in the picture below.
 
 ![img](./pic/operator.png)
 
-When using this Operator to write Pipline's Yaml file, you need to declare the following content according to the interface of resnet50_image_embedding class:
+When using this Operator to write Pipline's Yaml file, you need to declare the following content according to the interface of Resnet50ImageEmbedding class:
 
 ```yaml
 operators:
@@ -100,7 +100,7 @@ Here is the main file structure of the `resnet50-image-embedding` Operator. If y
 │   ├── requirements.txt  #The python dependency package for the pytorch model.
 │   └── model.py          #The code of the pytorch model, including the initialization model and prediction.
 ├── test_data/   #The directory of test data, including test.jpg
-└── test_resnet50_image_embedding.py  #The unittest file of the Operator.
+└── test_resnet50_image_embedding.py  #The unittest file of this Operator.
 ```
 
 ## Reference