Patent ID: 9674416
Date: 2017-06-06
CPC Classifications: H04N

Claim:
1. A method for controlling flash timing of an extension flash module cooperating with a mobile device to provide supplemental light when the mobile device having an image retrieval device is taking a photo, the image retrieval device including pixels arranged in rows, the method comprising: detecting a specific event before a flashable time period, wherein the flashable time period is a period from the time at which a last row in a specific frame begins exposure to the time at which a first row in the specific frame ends exposure, wherein the time period from when the specific event occurs to a flashable time in the flashable time period has a fixed length of time; and informing the extension flash module the occurrence of the specific event, so that the extension flash module triggers a flash instruction after a delay time from when the specific event occurs, such that the flash timing of the extension flash module is in the flashable time period; wherein the delay time is determined by steps including: (A) exposing a frame according to a given delay time; (B) checking the exposed frame and comparing brightnesses of the pixels with a reference threshold, to determine whether a pixel has a brightness lower than the reference threshold; (C1) when none of the pixels has a brightness lower than the reference threshold, setting the given delay time as a default delay time; (C2) when one or more of the pixels have a brightness lower than the reference threshold, and the pixel having brightness lower than the reference threshold is exposed earlier than half of the other pixels, shortening the delay time; and (C3) when one or more of the pixels have a brightness lower than the reference threshold, and the pixel having brightness lower than the reference threshold is exposed later than half of the other pixels, prolonging the delay time.