Arbitrarily Focused Video Using High-speed Liquid Lens

Summary

Focusing and blurring are essential techniques employed by photographers to emphasize a given photographic subject. Recent developments on synthetic digital photography permit the manipulation of focus and depth of field after the picture has been taken off-line.

In this work, we proposed a focus-scanning technique and present a simple algorithm to synthesize arbitrarily refocused images using a set of differently focused images or a 'focal depth image set'. However, conventional optical systems have slow response of focusing. This does not permit us to capture a focal depth image set of a dynamic scene, since the capturing process take considerable period and the difference of capturing timing of each image prevents time consistent synthesis of arbitrarily refocused images.

To solve this problem, we used a high-speed liquid lens called Dynamorph Lens(DML). DML has a liquid-liquid interface that can be arbitrarily reshaped to modify the focal length in a few milliseconds. Our setup consists of the DML and a highspeed camera. It is capable of achieving practical imaging performances, it can capture 100 focal depth image sets in a second. Such high frame rate enables us to even compute arbitrarily focused video, by stacking synthesized images in chronological order.

Figure 1 shows the synthesized image by the proposed method. The left image is single image of a captured focal depth image set. The middle and right images are synthesized image with different depth of field given by an operator from the captured focal depth image set.

Figure 1. Synthesized Image

References

1. Hiroki Deguchi, Hiromasa Oku, Masatoshi Ishikawa : Arbitrarily Focused Video Using High-speed Liquid Lens (Posters), 5th ACM SIGGRAPH Conference and Exhibition on Computer Graphics and Interactive Techniques in Asia (SIGGRAPH ASIA 2012) (Singapore, 2012.11.29-30)