TCG Challenge #1 CALCULATING CAMERA SNR Agenda •SNR definition •Calculation Method •Visual Results •Results •Conclusions Definition Traditionally, SNR has been defined as the ratio of the average signal value to the standard deviation of the background. However, when presented with a high-contrast scene, many imaging systems clamp the background to uniform black, forcing to zero, artificially making the SNR infinite. In this case a better definition of SNR is the ratio of the average signal value to the standard deviation of the signal. Method Following the definition we calculate the “average of the signal” defining each pixel along the samples as a signal and using the arithmetic mean. Arithmetic Mean (Mn) = (𝐼1 +𝐼2 +𝐼3 + ..... +𝐼𝑛 )/𝑛 In order to be able to calculate the standard deviation from each signal we then need to calculate the true value of each signal/pixel to conform the “True Image” we determine each pixel of this image using the arithmetic mean, the median and mode as average to determine which one yields better results. Median (Md) = 𝐼𝑛/2 𝑓𝑜𝑟 𝑠𝑜𝑟𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒𝑠 𝑜𝑓 𝐼 Mode (Mo) = the most repeated value Standard Deviation (SDi) = ((𝐼1 −𝐼𝑟 )2 + (𝐼2 −𝐼𝑟 )2 + … (𝐼𝑛 −𝐼𝑟 )2 )/2 Visual Results “True Image” ORIGINAL IMAGE “TRUE IMAGE” BASED ON MEAN Visual Results “True Image” ORIGINAL IMAGE “TRUE IMAGE” BASED ON MEDIAN Visual Results “True Image” ORIGINAL IMAGE “TRUE IMAGE” BASED ON MODE Median vs Mean vs Mode Results 20 log10 𝑆𝑁𝑅 40 35 30 25 20 15 10 5 0 Djalma Jonatas Victor mean median Graziele mode Renato Conclusion

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# TCG Desafio 1 - PUC-Rio