I have just revisited this and while I have managed to find a compromise it doesn’t look very elegant. The canvas size of the image is 3200x600 but the area available for institution logo/artwork is only 994x600 and this has to be in the centre of the canvas. Of this 200px at the bottom is reserved for the tag area.
https://deimos.apple.com/WebObjects/Core.woa/Browsev2/lse.ac.uk-dz
Our banner design uses a plain white background so I end up with tons of empty white space and a rather small logo/design in the middle. It looks especially bad on the desktop version of iTunes with a widescreen monitor. I could make the design larger so it looks better on desktop iTunes but if I do that the image is cropped on iPhone/iPad which is even worse. Whatever I do the design is compromised.
I understand the logic of trying to hit all devices with a single banner image but ultimately I think it would be much easier if we could upload a different image for desktop iTunes, iPad and iPhone. That would afford us the option to customise our banner design to fit the available screen real estate of each device.
We could completely re-design our banner, of course, so that it works better with the new banner spec but that’s a heck of a lot of work for no discernable benefit. Besides Apple may decide to change the spec again in the future and then we’d be back to square one.
btw – Syd, I think you have the same problem that I ran into. Your banner looks fine on desktop but it’s cropped on iPad (in portrait) and iPhone. To avoid this the design needs to go in the centre of the 3200x600 canvas and can be no larger than 994x600 of which 200px at the bottom is reserved for the tag area.