The first code 'vijay_ti_1' will extract the SIFT key-points and descriptor vector of each key-point in an image. For this code just one input image is required, and after performing complete SIFT algorithm it will generate the key-points, key-points location and their orientation and descriptor vector.
The second code 'vijay_ti_2' will first generate key points of original image and then ask for user's choice to enter whether they want to increase the image intensity or decrease it or change the value of sigma(scale) or they want to rotate the image. So the transformed image will be taken as second image and it's key points and descriptors are calculated.In final step this code will give number of key points matched between these two images and it's percentage on the command window.