Could you actually see photos made from RAW files?

Discussion in 'Digital Photography' started by aniramca, May 30, 2009.

  1. aniramca

    tony cooper Guest

    No, it doesn't. He is making a statement that proof can only be
    supplied by providing the opinion of experts, and that these experts
    would have to be in agreement with you. That is completely devoid of
    claim of authority. That assigns authority elsewhere.
    You are truly ignorant of what a non sequitur is. A non sequitur is
    statement or inference that does not follow logically in response to
    what has been previously said. He was challenged by "Huge" to "put up
    or shut up", and he logically proceeded to say that he had previously
    provided information about why he was in a position to know. While
    that statement did not contribute to the specific discussion, it
    logically followed what it was in response to.

    Just because a comment or statement does not address the specifics of
    a discussion, it is not a non sequitur. To be a non sequitur, it has
    to be a statement that is intended as a response to something said but
    does not follow the same logical path.

    For example, had Chris said "I work for a British firm, and that's why
    I am in a position to know" that would be a non sequitur. The facts
    that he has a job, and that the firm he works for is British, do not
    follow the same logical path of the statement he is responding to.
    Are you joking? I know that you have a poor understanding some words
    and terms because I've read many of your posts, but choosing to use a
    term that you have a complete lack of understanding of is beyond my
    That is pretty typical of you. You insist on defending yourself when
    you are patently in error, but are unable or unwilling to explain or
    justify your defense. Perhaps you can convince yourself that you are
    not in error, but I can't imagine that you can convince anyone else.
    tony cooper, Jun 5, 2009
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  2. aniramca

    Eric Stevens Guest

    You ignored my qualifier "when you are measuring it in integer steps?"

    In any case, if you are really unaware that voltage is ultimately
    quantized you should have a look at

    Eric Stevens
    Eric Stevens, Jun 5, 2009
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  3. aniramca

    Eric Stevens Guest

    I'm not confusing domains. I'm asking a valid question. No doubt you
    saw my brick-counting analogy. As for errors, I've acknowledged the
    existence of these and their statistical significance from my very
    first post in this much prolonged thread.

    Eric Stevens
    Eric Stevens, Jun 5, 2009
  4. aniramca

    Eric Stevens Guest

    Please don't put words in my mouth. All I know is that a number of
    Nikon cameras use software to modify the image somewhere between the
    sensor and the recorded raw data. You were arguing that no camera
    manufacturer uses software in such a fashion.

    Eric Stevens
    Eric Stevens, Jun 5, 2009
  5. aniramca

    Bob Larter Guest

    Well, it's true that there can be more than two levels in theory, but in
    practice the vast majority of digital electronics works in binary.
    We're talking about electronics here.
    All of those things pass through A2D & D2A circuits before interacting
    with the digital side of the systems. (Usually a DSP.)
    They're all analog-encoded digital signals, not digital signals in their
    own right.
    No kidding. I've only been doing digital electronics & interface design
    for about 30 years.
    That's the same point I've been trying to make.
    Well, Eric's correct to say that at a quantum level, you're dealing with
    integer numbers of photons & electrons, but he's missing the important
    point, which is that an image sensor doesn't have any way of 'counting'
    anything, & that the output voltage is merely an approximation of the
    input signal.
    Bob Larter, Jun 6, 2009
  6. aniramca

    Eric Stevens Guest

    Its only a list of searches relating to the problems of the
    quantization of voltage.

    Eric Stevens
    Eric Stevens, Jun 6, 2009
  7. aniramca

    Eric Stevens Guest

    I thought I had already bailed out. I only came back to deal with one
    of your misrepresentations. Now I'm going again.

    Eric Stevens
    Eric Stevens, Jun 6, 2009
  8. aniramca

    Eric Stevens Guest

    Which is then digitised to the necessary level of accuracy by
    comparison with a ramp signal.

    Eric Stevens
    Eric Stevens, Jun 6, 2009
  9. aniramca

    Huge Guest

    So, how many angels *are* there on the head of that pin?
    Huge, Jun 6, 2009
  10. aniramca

    Bob Larter Guest

    You're thinking of dual-slope conversion, as used in multimeters & the
    like. Dual-slope is very, very slow. For this sort of application (ie;
    fast) you either use a flash converter or a fast SAR converter.

    Eg; something like this:
    (Note that they aren't cheap.)
    Bob Larter, Jun 6, 2009
  11. aniramca

    daveFaktor Guest

    Eventually everyone who tries to get some sense out of Mr Davidson
    discovers doing that is about as simple as taking a digital photo with a
    K 1000 Pentax! It will never happen.
    daveFaktor, Jun 6, 2009
  12. aniramca

    Chris H Guest

    What evidence to you have for that statement?

    What are your qualifications besides being an ammeter programmer to make
    such a statement?
    Chris H, Jun 6, 2009
  13. aniramca

    Eric Stevens Guest


    Eric Stevens
    Eric Stevens, Jun 6, 2009
  14. aniramca

    Eric Stevens Guest

    Its too long since I was involved with anything like this but as far
    as I can see these all work by constructing a reference ramp signal
    (not necessarily linear) comprised of individual reference voltages
    with which to compare the input.

    You may use
    to define the limits of my understanding. :)

    Eric Stevens
    Eric Stevens, Jun 6, 2009
  15. aniramca

    Eric Stevens Guest

    Yeah. I did some research, way back in the mid 1960s. I did more with
    the introduction of digital music (whenever that was). So I do have
    some idea of what I am talking about.

    Eric Stevens
    Eric Stevens, Jun 6, 2009
  16. aniramca

    Eric Stevens Guest

    If you read and understand the papers you will realise that they are
    discussing the problems of the voltage being quantized.

    Eric Stevens
    Eric Stevens, Jun 7, 2009
  17. aniramca

    Bob Larter Guest

    That's not the case.
    From that article:
    * A direct conversion ADC or flash ADC has a bank of comparators,
    each firing for their decoded voltage range. The comparator bank feeds a
    logic circuit that generates a code for each voltage range. Direct
    conversion is very fast, but usually has only 8 bits of resolution (255
    comparators - since the number of comparators required is 2n - 1) or
    fewer, as it needs a large, expensive circuit. ADCs of this type have a
    large die size, a high input capacitance, and are prone to produce
    glitches on the output (by outputting an out-of-sequence code). Scaling
    to newer submicrometre technologies does not help as the device mismatch
    is the dominant design limitation. They are often used for video,
    wideband communications or other fast signals in optical storage.

    * A successive-approximation ADC uses a comparator to reject ranges
    of voltages, eventually settling on a final voltage range. Successive
    approximation works by constantly comparing the input voltage to the
    output of an internal digital to analog converter (DAC, fed by the
    current value of the approximation) until the best approximation is
    achieved. At each step in this process, a binary value of the
    approximation is stored in a successive approximation register (SAR).
    The SAR uses a reference voltage (which is the largest signal the ADC is
    to convert) for comparisons. For example if the input voltage is 60 V
    and the reference voltage is 100 V, in the 1st clock cycle, 60 V is
    compared to 50 V (the reference, divided by two. This is the voltage at
    the output of the internal DAC when the input is a '1' followed by
    zeros), and the voltage from the comparator is positive (or '1')
    (because 60 V is greater than 50 V). At this point the first binary
    digit (MSB) is set to a '1'. In the 2nd clock cycle the input voltage is
    compared to 75 V (being halfway between 100 and 50 V: This is the output
    of the internal DAC when its input is '11' followed by zeros) because 60
    V is less than 75 V, the comparator output is now negative (or '0'). The
    second binary digit is therefore set to a '0'. In the 3rd clock cycle,
    the input voltage is compared with 62.5 V (halfway between 50 V and 75
    V: This is the output of the internal DAC when its input is '101'
    followed by zeros). The output of the comparator is negative or '0'
    (because 60 V is less than 62.5 V) so the third binary digit is set to a
    0. The fourth clock cycle similarly results in the fourth digit being a
    '1' (60 V is greater than 56.25 V, the DAC output for '1001' followed by
    zeros). The result of this would be in the binary form 1001. This is
    also called bit-weighting conversion, and is similar to a binary search.
    The analogue value is rounded to the nearest binary value below, meaning
    this converter type is mid-rise (see above). Because the approximations
    are successive (not simultaneous), the conversion takes one clock-cycle
    for each bit of resolution desired. The clock frequency must be equal to
    the sampling frequency multiplied by the number of bits of resolution
    desired. For example, to sample audio at 44.1 kHz with 32 bit
    resolution, a clock frequency of over 1.4 MHz would be required. ADCs of
    this type have good resolutions and quite wide ranges. They are more
    complex than some other designs.
    Bob Larter, Jun 7, 2009
  18. aniramca

    Bob Larter Guest

    All of the ramp-based converters are too slow to be any use for reading
    an image sensor. It'd take *minutes* to read a single image.
    Bob Larter, Jun 7, 2009
  19. aniramca

    Eric Stevens Guest
    "Quantum electrodynamic theory of voltage carrying states..."

    Eric Stevens
    Eric Stevens, Jun 7, 2009
  20. aniramca

    John Turco Guest

    Eric Stevens wrote:


    Hello, Eric:

    "Dingbat," eh? Why don't youss dummy up, ya meathead, ya! <g>

    John Turco <>
    John Turco, Jun 7, 2009
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