It is rumored that the iPhone 5s’ current pixel count of 0.73 million pixels will bump up to a massive 1.5 million. In addition to this, the site suggests a smaller bezel will be introduced but it is not clear how this would be done.
Apple has all ready shook things up last year by altering their resolution to a taller design (much to the dismay of app developers) so it seems unlikely they would do the same thing this year.
On the other hand, Apple might feel pressured to further compete with Samsung’s Galaxy S4 pixel count of over 2 million.
The new iPhone is scheduled to start production in June, ready for a release in September. Given this, it is likely more details will be released as more people leak the specs of the parts.