"Lensless-camera technology for easily adjusting focus of video images after image capture"

Text and image from Japan Today, 11/26/16.

Hitachi Ltd has announced the development of a camera technology that can capture video images without using a lens and adjust focus after image capture by using a film imprinted with a concentric-circle pattern instead of a lens.

This camera technology makes it possible to make a camera lighter and thinner since a lens is unnecessary and allow the camera to be more freely mounted in devices such as mobile devices and robots at arbitrary positions without imposing design restraints.

Moreover, since it acquires depth information in addition to planar information, it is possible to reproduce an image at an arbitrary point of focus even after the image has been captured. Focus can be adjusted anytime to objects requiring attention.

Hitachi said it is aiming to utilize this technology in a broad range of applications such as work support, automated driving, and human-behavior analysis with mobile devices, vehicles and robots.

As for cameras mounted in mobile devices represented by smartphones and robots, which require designability, making them thinner and lighter while providing higher performance−without imposing restrictions on where they can be mounted−is being demanded. As a camera technology to meet that demand, there is an increasing anticipation of applying a technology called “computational photography” which is a scheme used in an optical system under the presupposition that image processing will be used after images are captured. As a camera utilizing this technology, a light-field camera, which records position and direction of light beams simultaneously and whose focus can be adjusted after images are captured, is well-known. However, a light-field camera is considerably thick since it needs a special lens. On the other hand, a lensless camera which is thin and light because it has no lens has been developed. Even so, processing of images captured by the camera incurs a heavy computational load.

Aiming to overcome the difficulties described above, Hitachi has developed a camera technology−based on the principle of Moiré fringes (that are generated from superposition of concentric circles) − that combines a function for adjusting focus after images are captured in the same manner as a light-field camera and features of thinness and lightness of a lensless camera which computational load incurred by image processing is reduced to 1/300.

Source: https://www.japantoday.com/category/technology/view/lensless-camera-technology-for-easily-adjusting-focus-of-video-images-after-image-capture