how to display my extracted feature index??

let say I have image I (400x300) size, i have used some method to get a new set of vector from image I (12500x1) size , but this set of date are juz the index number of some pixels in image I , and i now need to display my index number as a new image for me to have a clearer look, either one binary image or othe type of image will do .anyone have idea?