how to link post images to original image and not to thumbnail generated by WP

hello..

i want to link post images to the original image that i have uploaded and not to the thumbnails generated by the wordpress..

currently when i click on any image on my post i get smaller thumb (that is it is linked to smaller thumbnail) and when again click on that then i’m getting the original image i had uploaded…instead i just want to link to original image…

thanks in advance…