Method for focusing by using a pre-flash
US7493035B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 28, 2005 |
| Grant date | Feb 17, 2009 |
| Priority date | — |
| Expiry date | Feb 23, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B2215/05
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for focusing by using a pre-flash is provided. The method includes the following steps. First, the image sensor captures a first image of the object, wherein the average brightness of the first image is calculated to be Y0. Next, the image sensor captures a second image of the object with the aid of a first pre-flash having a first energy, wherein the average brightness of the second image is calculated to be Y1. Afterwards, the image sensor captures a third image of the object with the aid of a second pre-flash having a second energy, wherein the average brightness of the third image is calculated to be Y2. Then, the distance D to the object is calculated according to the brightness Y0 and the difference ΔY between Y1 and Y2. Finally, the image sensor adjusts the focus according to the distance D.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.