diff --git a/doc/imgs/cnn-ckim2014.JPG b/doc/imgs/cnn-ckim2014.JPG
deleted file mode 100644
index a1a8f1ec29adc75652ac79f1a71e0a3db11456e8..0000000000000000000000000000000000000000
Binary files a/doc/imgs/cnn-ckim2014.JPG and /dev/null differ
diff --git a/doc/imgs/cnn-ckim2014.png b/doc/imgs/cnn-ckim2014.png
new file mode 100644
index 0000000000000000000000000000000000000000..f1ad7558e4917c38d1dafc49f7bccac10219adee
--- /dev/null
+++ b/doc/imgs/cnn-ckim2014.png
@@ -0,0 +1 @@
+‰PNG
diff --git a/doc/imgs/tagspace.JPG b/doc/imgs/tagspace.JPG
deleted file mode 100644
index 3889db2d98c35cd494a77b710e6734fb4139d440..0000000000000000000000000000000000000000
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diff --git a/doc/imgs/tagspace.png b/doc/imgs/tagspace.png
new file mode 100644
index 0000000000000000000000000000000000000000..f1ad7558e4917c38d1dafc49f7bccac10219adee
--- /dev/null
+++ b/doc/imgs/tagspace.png
@@ -0,0 +1 @@
+‰PNG
diff --git a/models/contentunderstanding/readme.md b/models/contentunderstanding/readme.md
index 2d4482bd9bdd612bf1b28c79a4c951c4a4143598..fbe985a4dc8af1ebe716fad6ace0f1c6ede9a37c 100644
--- a/models/contentunderstanding/readme.md
+++ b/models/contentunderstanding/readme.md
@@ -27,12 +27,12 @@
 
 TagSpace模型
 <p align="center">
-<img align="center" src="../../doc/imgs/tagspace.JPG">
+<img align="center" src="../../doc/imgs/tagspace.png">
 <p>
 
 文本分类CNN模型
 <p align="center">
-<img align="center" src="../../doc/imgs/cnn-ckim2014.JPG">
+<img align="center" src="../../doc/imgs/cnn-ckim2014.png">
 <p>
 
 ## 使用教程