The optimum exposure decision for the enhanced image performance using a digital camera: Focusing on Exposure To The Right (ETTR) method

초록

Raw file records luminance value responding to each pixel of a digital camera sensor. In digital imaging, it has a characteristic that assigns the half of the whole levels for the first highlight stop and the half of the other for the second highlight stop, and etc., so that the darkest shadow stop is assigned the smallest level number of them. Therefore, when we exposure a digital camera, we should obtain the first highlight stop because it has the largest number of levels. In other words, controlling exposure to capture the first highlight stop is important in this kind of linear-distribution of raw file characteristic. Throughout the experiment, we verify the optimized exposure value and ISOs to maintain the first highlight stop which has the largest number of levels. In order to make it, we overexposure a scene with a raw file and convert it to underexposure in a raw file converting software. That is Exposure To The Right (ETTR) which can improve the image quality reproduction. Our research verifies the efficiency of ETTR with controlling the exposure range and ISOs. The result shows that the optimized exposure value is around + 1 2/3 stop over compared to the normal exposure and simultaneously with the high ISOs. Throughout this practical research, we can provide the effective ETTR information to consumers and manufacturers. This method will contribute the optimum image performance to maximize dynamic range and to minimize noise in a digital imaging. © 2010 IEEE.

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