Folks,
All of this is very nice, but where is a computer
monitor or print that can take advantage of these
capabilities? Regardless of the camera's
capabilities, it seems to be an 8-bit world when it
comes to viewing the photo.
Rick
--- Godfrey DiGiorgi <[EMAIL PROTECTED]> wrote:
> It's difficult to estimate how much advantage there
> is to having 16
> bits of quantization space vs 12 bits without more
> data, with respect
> to total dynamic range in stops or EV numbers.
>
> The analog capture range of the sensor from
> saturation input to noise
> threshold ("how much energy will max a photosite
> voltage rise to how
> little energy will trigger a photosite voltage
> rise") is one measure
> you have to know. You also have to take into account
> the typical
> gamma curve used to transform the linear capture
> space of the sensor
> to a rendered RGB image. The gamma curve compresses
> together the high
> values and spaces apart the low values to fit the
> captured data to
> the appropriate brightness range required for human
> vision. You also
> need a measure for 'acceptable noise' at the black
> point clipping
> level. Let's presume this latter is a constant,
> whatever it is.
>
> With todays 12bit sensors, quantization depth would
> net 12 stops
> tonal capture theoretically, but post-gamma
> correction the resulting
> output is in the range of 7-9 stops maximum, given
> the analog dynamic
> range limits of the sensor.
>
> If the K10D sensor has the same analog range of
> sensitivity as the
> current 6Mpixel sensor and 16 bit quantization space
> instead of the
> current 12 bit, what this means is that it can
> distinguish 16x more
> tonal steps in the analog range of its linear
> capture space.
> Processing this input with a 22bit image processing
> engine poses an
> advantage in reduced round-off error and accurate
> representation of
> the captured data into final storage form. If the
> analog dynamic
> range of the sensor is the same, it will still have
> the same 7 to 9
> stops of dynamic range, but they will be more
> accurately represented.
>
> That's as much as we can say without knowing the
> analog dynamic range
> of the sensor in question. Medium format backs with
> 16bit sensors
> typically have additional analog dynamic range in
> addition to larger
> quantization space, netting an increase in output
> dynamic range up to
> the 12 stop range with more accurate representation
> of tonal values
> captured ... there's a reason these MF sensors are
> expensive both in
> price as well as space and power requirements.
>
> BTW: 12 stops of analog dynamic range surpasses any
> film I've ever used.
>
> Godfrey
>
>
> On Sep 6, 2006, at 12:52 AM, Jostein Øksne wrote:
>
> > With all the talk of a 22 bit A/D converter for
> the K10D, and the
> > corresponding speculations of true 16-bit colour
> depth in the
> > raw-files, there are a couple of things I wonder
> about.
> >
> > Firstly, I wondered what the competition was
> doing. In the 35mm realm,
> > Canon use 12-bit colour depth in both 5D and
> 1DSmkII. I didn't check
> > other models. Leica, however, use 16-bit for the
> R-series digital
> > back. In the medium format realm, it seems that
> all the makers except
> > Mamiya use 16-bit. I have checked Sinar, Leaf,
> PhaseOne and Imacon.
> > Mamiya ZD use 12-bit colour depth, but 14-bit A/D.
> I couldn't find any
> > info on the A/D conversion for the other brands.
> >
> > Anyway, it seems that 12-bit is a standard for
> 35mm, and that 16-bit
> > colour rule the medium format world.
> >
> > Better dynamic range has been mentioned frequently
> in the discussion
> > of 16-bit colour, but I don't think I paid enough
> attention. How much
> > would 16-bit depth improve the dynamic range over
> 12-bit in terms of
> > f-stops? Is this going to be like going from slide
> film to colour
> > negatives, or is this on a different scale?
> >
> >
> > thanks,
> >
> > Jostein
> >
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>
>
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http://www.photo.net/photos/RickW
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