My user need to screen shot their error message throw my website. They should directly paste from clipboard in my website instead convert the jpeg. Preferable browser is Firefox. I try to use ZeroClipBoard but it works for words not images. Appreciated if anyone could advice and share any links for references.
Simple answer: you can't. There is no web-standards way to read binary data from the clipboard, I also do not believe that Flash or Silverlight does this either (Flash can expose bitmap data from the clipboard, but only under AIR, i.e. not in a browser context).
You could write a small desktop utility program that your users download and run, which will take a screenshot and upload it for them, but without that your users will have to paste the image into Paint, save to disk, and upload with an <input type="file">.