I think I inappropriately used the
word 'hide'.
What I assume I can send one image at a time using a servlet/action.
I want one character associated with the image to store somewhere,
so that I can hold all characters all together in a sequence to use it later for decision making.
I expect a response from user which is based on images.
Then I cross check the response with my stored characters.
The images is like puzzle and characters are like solution.
Action class creates threads for each request from different users.
I store character sequence in session & fetch the one for the user to update it.
I call five requests for five img tags for each user.
The images are stored in WEB-INF sub directory.
Because I can't allow users to see the image path.(Application's need)
In servlet/action I set
response.setHeader("Cache-Control", "no-cache");
JavaScript stores image one by one in img.src using action.do.