Rendition image through image servlet

What is the actual ask?

Meanwhile you can have a look at this Named Transform Image Servlet

-Kautuk

How to use image servelet?

Is there any example codes for this?

Using a Sling Servlet to render an image would be no different than a standard Java Sevlet to render an image.

Create dynamic image using Java | Half Wit

Also - as suggested by Kautuk - look at the ACS-Commons here - Named Transform Image Servlet