No problem, open the pic with paint, go to image, scrool down to resize and click. You will see horizonal and vertical at 100%. That is the size of your pic now. clear those numbers and insert 50% in each slot, this will shrink your pic to half high by half wide. If it is still to large , try it again. keep both numbers even to keep the picture's proportions even. then file and rename the photo, this will save the origonal as well as the shrunken copy. Try it and let me know how it went. Any trouble, I will help if I can.
The only real difference between a good tracker and a bad tracker is observation. All the same data is present for both. The rest is understanding what you are seeing.