New 21.5-inch Retina 4K models expected.
Retina iPad Mini's Display Criticized Over Poor Color Gamut and Accuracy
In an extensive review of the Retina iPad mini, AnandTech came away extremely impressed with the device but cited that color gamut issue as a significant disappointment.
Although display resolution is no longer a concern on the mini, color gamut hasn’t changed between the old and new minis. [...]DisplayMate's Ray Soneira has also taken a look at the Retina iPad mini's display in a "shoot-out" with the Kindle Fire HDX 7 and Google Nexus 7, with the Retina iPad mini's display registering a "distant 3rd place finish". The poor showing is due in large part to the iPad mini's narrow color gamut, which naturally leads to poor color accuracy.
The iPad mini with Retina Display has the same color gamut as the standard iPad mini, which is narrower than the iPad Air and less than the sRGB coverage we normally look for. The biggest issue here is that there are other smaller tablets in this price range that do offer sRGB coverage (e.g. Nexus 7, Kindle Fire HDX 8.9).
[T]he iPad mini with Retina Display unfortunately comes in with a distant 3rd place finish behind the innovative displays on the Kindle Fire HDX 7 and new Nexus 7 because it still has the same small 63 percent Color Gamut as the original iPad mini and even older iPad 2. That is inexcusable for a current generation premium Tablet. The big differences in Color Gamut between the Kindle Fire HDX 7 and Nexus 7 and the much smaller 63 percent Gamut in the iPad mini Retina Display were quite obvious and easy to see in the side-by-side Viewing Tests. [...] This all appears to be due to incredibly poor planning. Instead of moving up to the higher performance (and cost) Low Temperature Poly Silicon LCDs, Apple chose to continue gambling on IGZO, which has resulted in both production shortages and inferior products.
Soneira notes that the strong performance by Google/ASUS with the LTPS display in the Nexus 7 and Amazon with its Quantum Dots technology in the Kindle Fire HDX 7 "should be a wakeup call" for Apple, as the company is clearly no longer leading the industry in display quality.
One complicating factor in comparing the 7.9-inch 4:3 Retina iPad mini to the 7-inch 16:10 tablets from Google and Amazon is the fact that the 35% larger display area for the iPad mini would result in substantially higher costs if Apple were to shift to a different display technology such as LTPS. Still, to consumers comparing display quality of various tablets, the iPad mini appears to be a clear notch below its competitors.