There is an ongoing battle among technical geeks as to how many pixels our smartphones really need to have before it is overkill and beyond the detection of the human eye. Steve Jobs claimed it was 326 pixels-per-inch (PPI) and coined the term Retina Display - although we all know that was not entirely true. Many claim that the Full HD (FHD) display with a resolution of 1920 x 1080 pixels and about 420+ PPI on an average 5-inch display was already overkill. Those cries were brushed aside and now the Quad HD (QHD) display with a resolution of 2560 x 1440 pixels and 570+ PPI is becoming the norm on the latest flagship smartphones - the Samsung Galaxy S6 and LG G4, to name a couple, although HTC's new One M9 and Sony's Xperia Z3+ have stayed with FHD or 1080p.
Like it or not, the new Android M supports the next rung on the ladder of smartphone display resolutions - Ultra HD (UHD) or 4K displays with a resolution of 3840 x 2160 pixels! This means that we could see some 4k displays in 2015, given that Android M is to be released in the third quarter (July, August or September) 2015 and Samsung is readying itself to produce 4K displays. Sharp has just announced a new 5.5-inch 4K display for 2016 with 806 PPI. There have already been rumors that the new Galaxy Note 5 may sport a 4K display. To give you an idea of the pixel density of a 4K display...on a 5.7-inch screen, we are looking at a whopping 773 PPI! What a crazy number of pixels - does a 4K display really make sense?
We have to question if even the manufacturers believe in this increase in resolution - our source claims that on LG's first mainstream phone with QHD, the LG G3, they made a choice to have this over sharpening effect (see picture below) applied to the display. Is it possible they wanted to make sure that users could tell the difference between 1080p and 1440p? Raymond Soneira, president of DisplayMate Technologies claims that the "physiology of the human retina is such that there must be at least 477 pixels per inch in a pixelated display for the pixels to become imperceptible to the human eye at a distance of 12 inches (305 mm)." Others claim that Soneira was technically correct, but was being "picky." CultOfMac claims that most people have better than 20/20 vision and that at 12-inches, you need 900 PPI...they also point out that many people use their phones closer than 12-inches, so more pixels are needed.
The debate will go on and so will the pixel race - we will see 4K displays in the later part of 2015 or in early 2016 - whether we get to handle them or not. Compromises with a hand-held device that gets its power from a battery must be a consideration, as the higher the pixel density, the more power it uses. We must ask ourselves if we want a device with a 2K display that gives us a full 18 hours of service or a 4K display that lasts only 15 hours.