I made a nice channel banner today, and I worked hard on it with the little skill I have. I made a vector of myself, and then put the vector on a new banner. It look pretty okay to me, and it was a high resolution as well. HD. But then when I uploaded it to YouTube, the quality went waaay down. I also did not edit it in Photoshop, I used Gimp. Gimp has given me HD banners many many times, and when I view the image on my computer, it's HD as well. How can I fix this?