At 05:23 PM 3/10/2006 +0000, james wrote:
>Wayne S wrote:
>> At 03:01 PM 3/10/2006 +0000, you wrote:
>>
>>>The second way to get 256 combinations from 8 grains is if you *assume*
>>>each grain is twice the size of the next one. i.e. grains are not all
>>>the same size
>>
>> So you would get: 0,1,3,7,15,31,63,127,255 as values, not all 256 values.
>> ...
>
>not if *some* grains are on and some are not then you can fill in the
>missing numbers just like 8 bits in a computer byte give 256 combinations...
Yes, but you can not say to one grain "turn on if the light is this bright, and
any
left over light, go check with these grains", ... it is not that selective.
More likely
the grains bigger than X will be on and all grains smaller than X will be off.
You
can't have one small grain turn on and one big grain turn on and all other
grains
in between stay off. I'm sure it is more complicated than that, but you cannot
get
256 states of value from 8 binary weighted grains without some selection
process.
A/D converters have comparators that do this discrimination, and add/subtract
circuits for calculating remainder, or in the case of flash converters, 256
comparators for 8 bit converter.
You may be able to get a type of log response though with a distribution of
grains.
Which is a bit more discriminating than just on/off single sized grains.
Wayne
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