Digital BW, The Print

Question,

Why do you say red has " the highest energy of the three." I would 
expect that would depend on the spectrum of the light source and the 
bandwidth of the filters. Please elaborate.

Truman

Austin Franklin wrote:

>Hi Kevin,
>
>  
>
>>My scanner is a polaroid ss120.  It shines a white(ish?) light through
>>my silver film (which I assume is fairly neutral but with varying
>>density) and the intensity of resultant light is detected by a CCD
>>after the light passes through a colour filter.
>>    
>>
>
>Passes through THREE different color filters...  One, red, one green and one
>blue.  Resulting in three channels of color information.
>
>  
>
>>Why would the colour of the filter affect the relative intensities of
>>the light hitting the CCD.
>>    
>>
>
>Right or wrong, that doesn't have a thing to do with the reason.  It's the
>property of the CCD response/artifacting to different color lights.  Each of
>the three lights gives different responses to the CCD and has different
>artifacting.  Red, because it has the highest energy of the three, tends to
>be the fuzziest, simply because of what are called bloom and smear.  Bloom
>is basically saturation of the sensing element, smear is basically crosstalk
>between adjacent sensing elements, because of the intensity (this is the
>artifact that PMT scanners do NOT suffer from, as they scan one "spot" at a
>time).  Blue is the next worst, then green is the best...but not always.
>  
>



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