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I'm an electrical engineer trying to come up with a formula to turn a measurement of light level into lux. The photoresistor changes resistance logarithmically. Lux is also logarithmic. So the data I have collected looks like this:

My math is failing me right now; is there a formula for me to convert the raw readings into Lux that would fit this curve? How would I find it? The exponential regression for my two samples does not fit closely enough to be useful.

Raw Lux
0   0
68.5    30
81  40
88  55
91.5    70
95  85
98.5    100
100.5   115
102.5   130
103.5   140
104.5   155
106 170
109 320
110.5   460
113.5   600
114.5   750
115.5   900
116 1000

The exponential regression for my two samples does not fit closely enough to be useful.

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  • $\begingroup$ Wouldn't this be better for Stats.SE? $\endgroup$ – Mark Fantini Aug 25 '15 at 17:21
  • $\begingroup$ I don't know. When I was typing the title of this question there were a lot of similar ones. $\endgroup$ – Bob Baddeley Aug 25 '15 at 17:26

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