If you wish to scale and increase the size of any image but do not wish to compromise on the quality then there is a solution for sure.
Usually what happens is that when you scale your image you tend to lose pixels and quality but the solution to this thing is provided by the another type of images called Vector Images. There are two type of images, one that are formed from pixels and second formd from vectors.
While pixel images loses quality when scaled, vector images are effectless. So what you need is either an offline client that can convert your bitmap images to vector images or this website called Vector Magic that can convert your images for you.
Try it for yourself and i am sure you will like it too. Forget about losing quality while scaling images.