Smartphone imaging technology and its applications

Abstract

Thanks to their portability, connectivity, and their image performance – which is constantly improving – smartphone cameras (SPCs) have been people’s loyal companions for quite a while now. In the past few years, multicamera systems have become well and truly established, alongside 3D acquisition systems such as time-of-flight (ToF) sensors. This article looks at the evolution and status of SPC imaging technology. After a brief assessment of the SPC market and supply chain, the camera system and optical image formation is described in more detail. Subsequently, the basic requirements and physical limitations of smartphone imaging are examined, and the optical design of state-of-the-art multicameras is reviewed alongside their optical technology and manufacturing process. The evolution of complementary metal oxide semiconductor (CMOS) image sensors and basic image processing is then briefly summarized. Advanced functions such as a zoom, shallow depth-of-field portrait mode, high dynamic range (HDR), and fast focusing are enabled by computational imaging. Optical image stabilization has greatly improved image performance, enabled as it is by built-in sensors such as a gyroscope and accelerometer. Finally, SPCs’ connection interface with telescopes, microscopes, and other auxiliary optical systems is reviewed.

A Simple Way to Reduce 3D Model Deformation in Smartphone Photogrammetry

“…The smartphone casing, often less than 10 mm thick, creates a small space to place the lens and matrix. In smartphones, matrices with a resolution of 12 Mpix prevail, with a frame with a 4:3 aspect ratio [ 21 ]. In DSLRs, as well as in their mirrorless counterparts, the resolution of the matrices is often 20 Mpix or slightly more.…”

Why optics needs thickness

“…We compare these limits on d with specific designs for imagers and spaceplates in supplementary text S5, showing that these limits are both obeyed and approached in existing optimized designs. A 12-megapixel smartphone camera ( 26 ) would require >~1.7-mm thickness if designed with typical ( 26 ) (<45°) maximum ray angles, even with no thickness in the lenses themselves (i.e., within about a factor of 3 of actual ~5-mm smartphone camera thicknesses). The multilayer spaceplate design in ( 5 ) has a designed thickness of 44.6 wavelengths, which is quite close to the predicted limit of 30 wavelengths.…”

Realizing low-distortion in wide-angle lens with freeform optics technique

“…The parameters of the design case are given in Table 1. For the miniature camera lens, the relative flatness factor (r) of the optical system is given by [9]:…”