Mobile retina banners

Éva Szántai

Director, Product & Technology

Many times the people responsible for mobile adverts look strange, when they see the specifications 600x500px or 640x100px for mobile banners. Then comes the usual question: such a huge size for such a small display? Is it going to cover the whole screen? The banner is not going to cover the whole screen, naturally. Not even half of it. Let’s see why:

The world of mobile develops extremely fast and the developments are going towards phones that are bigger with better resolutions. When we look at the specifications of the newest mobiles, we see HD, fullHD and even QHD displays. This means that our smartphones’ displays have the same quality as our laptops and PCs, in a much smaller device. Of course these phones do not display all those pixels, e.g. the iPhone 4 has 640 pixels written in their specifications but they only display 320 pixels, which is called double pixel density, aka retina display.
Not only mobile website developers have to prep for big smartphone displays but also people creating the banners and the adservers have to be ready. Here is what you should know about mobile retina banners.
Banners have retina/HD resolution when we upload bigger pictures. Let’s look at an example: an iPhone 4. The phone – as I already mentioned – can display 640 pixels. If we’d like to serve a 320×50 pixels photo, the advert would be blurred, since only every second pixel of the phone gets a banner pixel.
Therefore, if we happen to upload a 640 pixels wide – i.e. 640×100 – picture, then every pixel gets a point to be displayed, and we get a sharp photo.

This would not work if there would not be any smart adservers in the world that can serve them. I think we all have seen mobile advertisements, where only half of the picture was visible because the other half was cut or messed up the whole mobile site due to its size. In this case the good new is that they’ve thought about large resolutions, but something went wrong in the adserver. These systems serving advertisements should get ready for the changed size of banners, instead of the 320×50 IAB standards they’ll have to serve 640×100 pictures without any errors.

If you think about it, even these banners are blurry on fullHD and QHD displays, but our eyes are not able to comprehend, since these resolutions are so large. But who knows where the constant growth of smartphone displays is going to lead us?

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