Camera flash module and method for controlling same
First Claim
1. A method, comprising:
- capturing a first test image without using a flash;
capturing a second test image using the flash with a predetermined intensity;
obtaining a difference image indicative of a difference between the second test image and the first test image, wherein the difference image comprises a plurality of difference image pixels, each difference image pixel having a pixel value;
identifying a reference pixel among the difference image pixels, wherein the first test image comprises a first test pixel corresponding to the reference pixel, and the second test image comprises a second test pixel corresponding to the reference pixel; and
computing illumination amount by the flash for subsequent image capturing based at least partly on pixel value of the first test pixel and pixel value of second test pixel.
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Accused Products
Abstract
An auto-exposure algorithm for controlling a camera flash uses image processing to identify important areas of the image affected by the flash, while disregarding highly reflective/illuminated areas and uses a ND filter to linearize the flash triggering with highly reflective scenes. The camera flash is controlled by the auto-exposure algorithm in two stages:
a pre-flash stage followed by a main-flash stage. In the pre-flash stage, two images are captured under the same camera settings regarding the exposure time, gain, iris and resolution. One image is captured with flash and one without. From the difference between the two images, a reference pixel is used to determine the flash intensity in the main-flash stage.
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Citations
20 Claims
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1. A method, comprising:
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capturing a first test image without using a flash; capturing a second test image using the flash with a predetermined intensity; obtaining a difference image indicative of a difference between the second test image and the first test image, wherein the difference image comprises a plurality of difference image pixels, each difference image pixel having a pixel value; identifying a reference pixel among the difference image pixels, wherein the first test image comprises a first test pixel corresponding to the reference pixel, and the second test image comprises a second test pixel corresponding to the reference pixel; and computing illumination amount by the flash for subsequent image capturing based at least partly on pixel value of the first test pixel and pixel value of second test pixel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 17, 18)
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13. A flash module for use in a camera, the module adapted to control a camera flash, said module comprising:
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a mechanism for triggering the camera flash; and a processor arranged to receive image data from the camera, wherein the processor is adapted to carry out; capturing a first test image without using the camera flash; capturing a second test image using the camera flash with a predetermined intensity; obtaining a difference image indicative of a difference between the second test image and the first test image, wherein the difference image comprises a plurality of difference image pixels, each difference image pixel having a pixel value; identifying a reference pixel among the difference image pixels, wherein the first test image comprises a first test pixel corresponding to the reference pixel, and the second test image comprises a second test pixel corresponding to the reference pixel; and computing illumination amount by the flash for subsequent image capturing based at least partly on pixel value of the first test pixel and pixel value of the second test pixel. - View Dependent Claims (14, 15, 16)
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19. An apparatus, comprising:
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means for capturing a first test image without using a flash and a second test image using the flash with a predetermined intensity; means for obtaining a difference image indicative of a difference between the second test image and the first test image, wherein the difference image comprises a plurality of difference image pixels, each difference image pixel having a pixel value; means for identifying a reference pixel among the difference image pixels, wherein the first test image comprises a first test pixel corresponding to the reference pixel, and the second test image comprises a second test pixel corresponding to the reference pixel; and means computing illumination amount by the flash for subsequent image capturing based at least partly on pixel value of the first test pixel and pixel value of second test pixel, wherein the reference pixel is identified based at least partly on a highest pixel value among the difference image pixels - View Dependent Claims (20)
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Specification