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What I am trying to do is convert the color values 0-255 into a decimal form between 0-1 for example 127.5 = 0.50 or 191.25 = 0.75. I know this is simple math but the problem is that with the program I am writing a 0 represents ON and a 1 represents OFF so with a color code of 255 it should actually be equal to 0.0 and with a color code value of 0 it should equal 1.0. Can someone please tell me how to solve this math has never been a strong point of mine.

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closed as off topic by Jim, Micah, Asaf Karagila, Alexander Gruber, Chris Eagle Feb 24 '13 at 22:08

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Shouldn't this be on StackOverflow, not Mathematics? –  AJMansfield Feb 24 '13 at 20:26
    
I posed this on StackOverflow and actually got the same answer as below but for some reason I guess I was not doing the equation right and kept coming up with the wrong answer. –  Yamaha32088 Feb 24 '13 at 20:27
    
So you both posted in the wrong place, AND double posted. –  AJMansfield Feb 24 '13 at 20:29
    
That would be correct –  Yamaha32088 Feb 24 '13 at 20:31

2 Answers 2

up vote 6 down vote accepted

How about you use the function $f(x)=1-x/255$?

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this works for 127.5 but for 191.25 you would get 0.25. the subtraction from 1 is not necessary. –  franklin Feb 24 '13 at 20:21
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the 0.25 for 191.25 is what I actually want in this case it seems strange and backwards I know –  Yamaha32088 Feb 24 '13 at 20:24
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@franklin That is the OP's intent behavior, so the subtraction from 1 is in fact necessary to perform the OP's task. –  AJMansfield Feb 24 '13 at 20:24
    
ah. thanks @AJMansfield. actually then this would be the correct answer. –  franklin Feb 24 '13 at 20:24
    
thanks a lot I will accept answer when time allows –  Yamaha32088 Feb 24 '13 at 20:29

All you need really is $f(x) = x/255$ for example if you put the input color as $x$ your output should be $f(x)$ as in, $x = 127.5$, $f(x) = 0.5$. It's a proportion of your input value to the entire spectrum, 255.

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