ABSTRACT
The design of an efficient OIS system is highly dependent on the characteristic of the hand shake. Therefore, we will start this chapter with an example of an experimental hand-shake characterization performed in the context of smartphone cameras. The image blur generated by the photographer’s hand shake during the exposure time of the image is very variable from one person to another, and for the same person, from one picture to another. We present a model of the average hand shake of a smartphone obtained from a statistical analysis of a large number of experimental recordings. In the following section, we analyze the contribution of the hand shake to the image blur and we give an estimation of the consecutive image blur in terms of number of pixels as a function of the exposure time and of the image sensor resolution. We present the intrinsic optical noise limits in the context of smartphone cameras. This theoretical study highlights the minimal picture integration time that is required for different shooting conditions in order to obtain pictures with an acceptable noise level and it points out when OIS is required. In the context of miniature smartphone cameras, this result can be compared to the photographer’s rule of thumb giving the maximal exposure time to obtain sharp pictures with a 24 × 36 mm film format. We describe some OIS technologies for smartphones and a theoretical model simulating the blur reduction efficiency as a function of the OIS optical actuator characteristics and of the picture integration time is given in the last section.
