The informal inspection, performed by Repair Labs (via TechCrunch), yielded side-by-side images of the mini, the first-generation iPad, iPad 2, third- and fourth-generation iPad with Retina display, all taken from a 150x power microscope.
As seen in the resulting photos, the red, blue and green (RGB) blocks that comprise a single pixel are clearly visible, with pixel densities ranging in size from the original iPad and iPad 2's relatively low-resolution 132-pixels per inch screens, to the 264-pixels per inch panels found in the third- and fourth-generation iPads. Falling between the two pixel densities, but leaning more toward the iPad 2, is the iPad mini's display, which has the same resolution as the original iPad and iPad 2, but boasts a higher 164ppi pixel density due to its smaller 7.9-inch screen.
Source: Repair Labs
Comparing the fourth-gen iPad with the iPad mini, the pixels in the Retina display are only two-thirds the size of those found in the smaller tablet. This is in contrast to the iPad 2, which has pixels double the size of the fourth-gen iPad's.
"This means the difference between the two, is less noticeable," Repair Labs wrote. "In fact, to the naked eye, it?s negligible."
Pixel size of the iPad mini's screen (left) versus that of the fourth-generation iPad (right).
When Apple announced the iPad mini in October, some were concerned that the lack of a Retina display would hinder sales of the device as the company is in the process of moving most of its products to the high-resolution panels. It appears that Apple is positioning the tablet as a completely new sub-market, however, and is using the older screen tech to keep prices down.
Many have speculated that the next iPad mini will feature a Retina display as manufacturing yield rates stabilize to drive down component costs, though at this point the statements are mere rumors with no supporting evidence from supply chain sources.