[filmscanners] RE: Dynamic range

["Vincent Cleij" <vcleij@planet.nl>]

Hi Roy,

With your arguments a 1 bit file has the same dynamic range as a 16 bits
file because value 0 in a 1 bit file represents the same black level as
value 0 in a 16 bits file and value 1 in a 1 bit file represents the same
white level as value 65335 in a 16 bits file. This is of course not the
case. Dynamic range is the ability to distinguish tonal differences. If a
certain system is able to distinguish pure black and a slightly less black
and at the same time is able to distinguish pure white and a little less
white we say that its dynamic range is large. So the number of bits relates
to the dynamic range and 8 bits system have, in general, a lower dynamic
range then 16 bits systems. It doesn't mater if you are talking about files,
scanners, digital cameras or any other system.

Thanks,
Vincent



>> ...
>>> Of course, the number of bits LIMITS the dynamic range, I've always said
>>> that...but BTW, that contradicts Roy's last round, as he claims that 8
bits
>>> has the same dynamic range as 16 bits...
>>
>> Yes, I don't agree with Roy on this point.
>>
>> Julian
>>
>
>Hi Julian,
>
>I'm curious whether we're talking about two different things or that you
>disagree with what I was actually talking about.
>
>It think that your post (in response to Austin) was talking specifically
>about scanner output.  In other words the phrase "the number of bits LIMITS
>the dynamic range" was in the context meaning "the number of bits in a
>scanner LIMITS the dynamic range of that scanner".  In this context I
>entirely agree -- a 16-bit scanner has more dynamic range than an 8-bit
>scanner.
>
>My 8-bit versus 16-bit comment was in a very different context.  I was
>talking about a 16-bit Photoshop that was ready to be printed.  Thus
>value 0 was the max black and value 65535 was the max white.   At this
>time the file was converted to 8-bit such that value 0 represents the
>same max black as 0 in the 16-bit file, and value 255 in 8-bit file
>represents the same max white as 65535 in the 16-bit file.  So both
>files represent the same black to white range.  In this context I
>say the 8-bit file and the 16-bit file have the same dynamic range
>because they represent the same tonal range on a output print.  The
>endpoints are the same only real difference is how many levels are in
>between.
>
>So, is there disagreement?  If so I'd like to know why and how you
>look at it.
>
>Thanks,
>Roy
>

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