@abhishek: If you are using a 1×1 pixel image, you could just convert it into a data URI. Then you don’t have a HTTP request to worry about. It’ll look similar to this:
The only problem is there is no way to cache it (I think) and you will have to repeat this format every time you need the same image.
I got the above img tag example from wikipedia but you can use an online converter to make your own URI string. Please note that larger images make for much larger URI strings!
Edit: Now that I think about it, a better method for you would be to use one of the other images that you are already using on the page and just clip it. That is if that image has a transparent area. So assuming the top left corner of your image is transparent, your code would look something like this:
clip:rect(0 1px 1px 0);
Here is a post that Chris made about it with more detail.