"Chris Malcolm" <cam@[EMAIL PROTECTED]
> wrote in message
news:661j7oF2hmljaU1@[EMAIL PROTECTED]
> In rec.photo.digital Floyd L. Davidson <floyd@[EMAIL PROTECTED]
> wrote:
> > Chris Malcolm <cam@[EMAIL PROTECTED]
> wrote:
> >>In rec.photo.digital Mr.T <MrT@[EMAIL PROTECTED]
> wrote:
> >>>> I suspect you may be confusing resolution with range. The problems
you
> >>>> refer to are problems of range.
> >>
> >>> Did anyone mention resolution, can't see it in this post myself.
> >>> (other than your latest "input")
> >>
> >>The connection between number of encoding bits and resolution of the
> >>resulting encoding in analogue to digital conversion is probably
> >>something else your photographic education omitted. If so then you
> >>wouldn't have realised that you were the one who brought it up by
> >>suppposing that the number of encoding bits in the camera sensor
> >>affected dynamic range. It doesn't. Any number of bits can encode any
> >>dynamic range you like. What the number of bits affects is the
> >>resolution with which that dynamic range is encoded.
>
> > Your description is incorrect. The sensor is analog, it
> > has no such thing as a "number of encoding bits". The
> > digital to analog conversion is not integral to the
> > sensor,
>
> In some sensors it is, but that doesn't really matter. I was referring
> to the combination of sensor and ADC as an integral unit since in a
> digital camera there is no way of accessing the sensor data in any
> other way than via the ADC. They are functionally integrated.
>
> > and of course the analog output from a sensor
> > has a known dynamic range; however, while the number of
> > bits, e.g. 12 or 14 are now common, does not determine
> > the dynamic range of the sensor output, it can and
> > sometimes does limit the dynamic range of the resulting
> > digital signal (e.g., when the dynamic range of the
> > digital format is less than the dynamic range of the
> > analog output from the sensor).
>
> You're perfectly correct. We've had this argument before. I note that
> our last argument taught you something, since you now no longer claim
> a necessary connection between the number of bits and the dynamic
> range, merely a contingent one.
>
> > I.e., no matter what
> > the dynamic range of the sensor, the *maximum* possible
> > dynamic range for a digital signal is limited by the
> > number of bits/sample to (6.02 * N) + 1.76 where N is
> > the number of bits.
>
> That begs the question, because the normalising assumptions behind
> that equation specify what kind of dynamic range we're dealing
> with and how that dynamic range should be encoded. You should be able
> to find those assumptions from the textbook you got the equation from.
>
> > Suggesting that "any number of bits can encode any
> > dynamic range you like" is indicates that you *still* do
> > not understand the significance of digital technology.
>
> I've been working with it since 1964. I was writing software to
> convert RAW digital camera images and making my own cheap digital
> cameras from dynamic RAM chips in 1980. I was teaching digital
> technology at postgrad level in 1986. But you're right, digital
> technology has quite revolutionary significances which I'm still far
> from fully comprehending.
>
> You haven't however yet convinced me that you have a better grasp of
> it. :-)
>
> > "The resolution with which that dynamic range is
> > encoded" is no different than saying "the distortion
> > generated by encoding", which is exactly what *limits*
> > the dynamic range. In essence, quantization distortion
> > increases if the step size increases.
>
> Of course it does. That's where the assumptions behind your equation
> come in. You're treating perfectly good engineering compromises as
> though they were scientific principles.
>
> >>There is a tendency for technology to progress on a number of fronts
> >>at the same time. Hence there has been a tendency for improvements in
> >>dynmanic range to accompany improvements in encoding resolution, just
> >>as improvements of dynamic range have also been accompanied by
> >>improvements in battery capacity and optical zoom ranges. But there's
> >>no necessary connection between them.
>
> > The fact is that as the dynamic range of the analog
> > sensor has increased, camera manufacturers have
> > progressed to using more bits per sample in order to
> > retain, in the digital signal, the dynamic range that
> > exists in the analog range.
>
> The assumption you're not stating is that they were trying to encode
> the new increased dynamic range at the same or higher resolution than
> the old dynamic range. There is NO connection between number of
> encoding bits and dynamic range without making assumptions about
> resolution. The equation you like to quote to "prove" your point
> embodies such assumptions.
>
> > You are suggesting that 14
> > bit ADCs were not available 10 years ago when digital
> > cameras were moving from 10 bit to 12 bit ADCs.
>
> No I'm not. 16 bit ADCs have been available for decades. Camera makers
> haven't been using the state of the art stuff you find in research
> labs, they've been using what could be packaged and sold to a mass
> market.
>
> > That is
> > not true. While certainly there have been improvements
> > in 14 bit ADCs over the past 10 years, it is a fact that
> > if CCD sensors had required 14 bit ADCs ten years ago,
> > they would have been used. 14 bit ADCs were not used
> > until the dynamic range of the sensors improved to
> > greater than what a 12 bit ADC can provide.
>
> You're perfectly correct, and the point you're missing which I'm
> insisting on making is the engineering compromises and normalising
> assumptions that lie behind that fact.
>
> I think the dispute between us is simply that I'm not allowing you to
> state engineering compromises and normalising assumptions as though
> they were scientific principles or mathematical theorems. I'm not
> disagreeing with them as perfectly good engineering compromises.
What part of the binary system do you not understand?
1 binary bit is a factor of 2
1EV stop is a factor of 2 by definition.
How much simpler can it be for even a moron to grasp the fundamentals?
No need to get confused with encoding systems, they are not part of the
fundamental physics involved.
MrT.
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