Reports suggest that the screen resolution of the second-generation iPad could be 2,048x1,536 - a massive improvement on the 1,024x768 resolution of the original.

Graphics in Apple's iBooks app and spotted by Twitter members @stroughtonsmith and @xuzz show four different bookmark icons - one for iPad, one for iPad x2, one for iPhone and one for iPhone x2. The graphic can be seen on the Mac Rumours website.

According to Mac Rumours, Apple has now removed this graphic from the iBooks app. But it is suggested that it is evidence that the next-generation iPad will have a much higher resolution than the current model.

The iPhone's 'retina' display of 640x960, up from 320x480 on previous iPhones, effectively quadrupled the number of pixels on the device's screen with a dpi (dots per inch) density of over 300.

Though boosting the iPad's screen resolution from 1,024x768 to 2,048x1,536 would only give a dpi of around 260, this would still likely make a big difference to the human eye. However, it would also probably require a great deal more processing power than offered by the original iPad.

Whether or not the reports have any truth in them, it could be a long time before UK customers will be able to see how good the screens are for themselves, with suggestions that the iPad 2 might not launch in the UK until July.