Adding a border around an image can improve readability. It is easy to do with article text images.
Adding a border around an image
On the article creation page click the 
Insert/Edit Image icon
Insert an image into the text of the article.
Click on the image to select it.
Go to Format>>Formats>>Bordered Image
How to wrap text around an image
Adding a border around a table
Create a 
table and insert an image.
Double click the table to select it
Go to Format>>Formats>>Bordered Table
How to wrap text around a table
Adding a border around a table cell
Create a table and insert an image.
highlight the cell content to select it
Go to Format>>Formats>>Bordered Cell
The table in the article will display like this
How to add a caption to an article text image
How to add a caption to an article text image
