Could you actually see photos made from RAW files?

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

  1. aniramca

    Guest Guest

    it works in cs3 too.
    Guest, Jun 2, 2009
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  2. aniramca

    Guest Guest

    right, and i explained how earlier in the thread.
    Guest, Jun 2, 2009
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  3. aniramca

    Chris H Guest

    This is not correct. There are plenty of mixed devices about. Analog
    Devices make a few of them.

    Perfectly correct.
    Yes it is. What is more I can supply the tools to write the firmware.
    (I can't tell you which but We have supplied software/firmware tools to
    more than one OEM digital camera company (P&S variety)
    Chris H, Jun 2, 2009
  4. aniramca

    Eric Stevens Guest

    When you go to court you swear to tell the truth, the whole truth and
    nothing but the truth. Even if what you quote of mine is quoted
    accurately, leaving out large chunks of it has me saying something
    other than what I actually said.

    It can be OK for you to do that if you indicate that that is what you
    have done. But you don't do that. You just delete blocks of text. This
    can result in me appearing to say something other than what I actually
    said. It can also result in the deletion of the explanation and
    justification of what I did say.

    It took me a while to wake up to what you were doing and then I found
    that when I responded to you I had to go back to my previous article
    to discover what you had actually done to it in your response to which
    I was responding.

    You can't claim that you don't know any better than this if only for
    the twenty years of experience you have had with Usenet. What you have
    been doing would not have been tolerated for one second twenty years
    ago (yeah - I was there too).
    If you do know better, why do you do it?
    What? That "you have been round Usenet more than long enough to know

    "Please remember that when you do snip portions of a person's
    post, it's extremely important that you not only indicate that
    you've done so, but also where you've done so. [5]

    The commonly accepted way to indicate snips is to simply insert
    the string "<snip>" (or similar notation) on a line by itself at
    the spot where the deleted text used to be. "

    I expect that it will be possible to show you are a liar if you claim
    to have never been exposed to this practice in you 20 years of Usenet.
    And they mark where they have snipped!
    Haw. You are now claiming that it is possible to have a continuously
    variable number of electrons. I maintain the number of electrons can
    only be represented by integers.
    The output of the sensor is an electrical charge. The electrical
    charge is dumped into a charge amplifier and it is this which outputs
    the voltage. This is the first step in transforming sensor image into
    the RAW data file.
    The output of the charge amplifier is then digitised. This is the
    second step in transforming sensor image into the RAW data file.
    In the case of the Nikon D300 the RAW file can be output as either 12
    bit or 14 bit. It is likely that before it can be transformed into
    either of those formats it is processed in the camera in some other
    Before it hits the RAW file, the data is further massaged.
    Not so. The digital value of say 1612 corresponds with only one state
    of the particular sensor element. If you know the chain of
    transformations between the sensels and the corresponding data of the
    RAW file you can work it backwards to derive from the RAW file the
    state of the individual sensels which gave rise to the data in the
    first place.
    But you do if you understand the nature of the transformation.
    Of course I have. What exactly does he have to do with it?
    You had led me onto the garden path for that one. Nevertheless there
    is software between the formation of the image on the sensor and the
    writing of the data to the RAW file. That is why/how various problems
    (e.g. vertical stripes) can be cured by a firmware upgrade.
    Its not at all nonsense, even if you think it is so.
    It was meant to be good-natured banter.
    You are I suppose referring to my use of "Subject to statistical error
    limitations,.. ".
    Is this now how you are explaining your belief that more than one
    image corresponds to a patricular RAW file? Its like saying more than
    one house can be built from a set of plans because the builder will
    read their tape measure slightly differently each time. Well, that's
    what I meant when I wrote of "Subject to statistical error
    We are talking about images projected on to the sensor. There is fixed
    correlation between the light which has fallen on a sensel and the
    data which is recorded in the RAW file. Similarly there is a fixed
    correlation between the data in the RAW file and the light which fell
    on the sensel which created the data. If you know one, you can
    determine the other.
    And uncertainty in A to Conversion.
    That's one form of transformation. another is where in a system of
    cartesian coordinates the point of origin is changed. This requires
    that all the coordinates defining a shape be changed (transformed) but
    does not change the shape. Or the data may be transformed from
    cartesian format to polar. Encoding a message does not change the
    message but it does transform it.
    Why not?
    There are an awful lot of people who wish it was.
    I think you are back to the image created on a screen (or whatever)
    from the RAW data.
    You forget you are dealing with electrons, which can only be described
    by integer numbers.
    for a better indication of the number of electrons you can expect to
    deal with: 50,000 or more.
    Congratulations! 40 years ago you were working in Bell Labs along with
    Boyle and Smith! And I thought you were only a psychologist.

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

    Bob Larter Guest

    That's incorrect. In a Bayer pattern image sensor, for example, fully
    half of the sensels can't 'see' red or blue light. As a theoretical
    example, imagine if you projected a series of images onto the sensor,
    patterned such that the only difference was in the amounts of red/blue
    light on the green-sensitive sensels, you would get a series of
    identical RAW files. This is obviously a very contrived example, but it
    demonstrates the possibility.
    Bob Larter, Jun 3, 2009
  6. aniramca

    Bob Larter Guest

    Yes. If you think carefully about how an image sensor works, it's obvious.
    Bob Larter, Jun 3, 2009
  7. aniramca

    Bob Larter Guest

    By that exact same logic, resistors capacitors & transistors should be
    called "digital" devices, but they aren't. The industry definition of
    "digital" is something that only works with binary levels. Everything
    else is called "analog".
    In summary:
    Analogue electronics (or analog in American English) are those
    electronic systems with a continuously variable signal. In contrast, in
    digital electronics signals usually take only two different levels. The
    term "analogue" describes the proportional relationship between a signal
    and a voltage or current that represented the signal.
    Bob Larter, Jun 3, 2009
  8. aniramca

    Bob Larter Guest

    Go figure, I had no idea that was the case. I'll have to give it a try.
    Bob Larter, Jun 3, 2009
  9. aniramca

    Bob Larter Guest

    This is the part I haven't tried. How do you do it? Can it be done from
    Bob Larter, Jun 3, 2009
  10. aniramca

    Eric Stevens Guest

    I may be missing something but its not obvious to me.

    A lens directs light from a scene so as to form an image on the
    camera's sensor.

    Different parts of the image fall on individual sensels which, in the
    time allowed to them, capture photons which generate electrons. The
    accumulated electrons form an electrical charge in each sensel.

    According to the type of sensel, the charge is 'read' in one way or
    another, and the quantity of charge converted to digital data.

    The digital value of the charge is saved in an array which enables the
    value of the charge for each individual sensel to be mapped to the
    position of the sensel.

    Leaving out the question of whether or not the data is further
    massaged by the camera before-hand, the data array is saved as the RAW
    data file for the image.

    That original image on the sensor is characterised by by the raw data
    array. Any change in the image gives rise to a different data array.
    As far as I can see only the one image can give rise to a particular
    data array.

    I would be grateful for an explanation of how a different image can
    give rise to the same data array.

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

    Eric Stevens Guest

    Yes, I will accept that, but thats a very special case. It would in
    fact require a source image composed of elements below the resolution
    of the sensor. I don't think that's what we had in mind.

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

    Eric Stevens Guest

    "In a digital circuit, a signal is represented in discrete states or
    logic levels." - but they don't have to be binary.
    "Any change in the signal is meaningful, and each level of the signal
    represents a different level of the phenomenon that it represents."
    This isn't the case with the output from a charge amplifier. 0.050,000
    volts represents 50,000 electrons. 0.050,000,4 volts still represents
    50,000 electrons. But 0.050,001 volts represents 50,001 electrons as
    does 0.050,000,6 volts.
    " ... _usually_ take only two different levels." But what about Rambus
    XDR memory which uses three different levels? Two levels are used
    because they are the simplest.
    It still has to be capable of accurate digitisation and to that extent
    it is digital.

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

    tony cooper Guest

    It must not be all that risky. You do it so often and don't seem to
    be the worse for it.
    tony cooper, Jun 3, 2009
  14. aniramca

    Eric Stevens Guest

    This is certainly a problem at low light levels but, by and large,
    this is what I meant by "statistical error limitations". When you get
    to this level you are in danger of introducing quantum theory.
    The sensel counts photons which it converts to photons. The data is
    integer. This is converted to binary digital data. You might say it is
    encoded. I would say it is transformed. It doesn't matter which either
    You should, if you want me to know what you are talking about. But of
    course the 'transformation' can be run backwards, even if you don't
    use the same hardware. Its the algorithm you have to reverse.
    Whoever argued otherwise?
    Changes are quantized. A different image on the sensor gives a
    different number of electrons which are transformed into different
    digital data.
    All you have done is reiterate the claim. Can you give a step by step
    explanation along the lines of the one I have just given?

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

    Eric Stevens Guest

    Then what do you think firmware is? Its a mixture of hardware and
    And that's a bit of dishonest argument, unless you insist on believing
    that that the digitisation of the sensel charges is the entirety of
    the process.
    But he never claimed it was just for those functions.

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

    Eric Stevens Guest

    Its not a question of current. Its a question of the number of
    The output of a sensor is electron charges, which is quantized.
    Who is trying to say it is meaningful to anything else?
    Yes, and it does.
    So you keep saying. But if you can measure it with sufficient accuracy
    and discard rounding errors (as can easily be done) you can read the
    output as integer - which is digital.
    It is the A to D converter which precisely measures the voltage to it
    to be able to read as integer numbers. That's what I was trying to
    explain to you above when you asked "Is that supposed to make sense?"
    At least that's got you away from insisting that they always have to
    be binary.
    Electrons. Integer number of electrons. Nothing analog about integer

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

    Eric Stevens Guest

    I mightn't find the rules but I can find plenty of examples where that
    was what was done.
    Can I quote that to the Floyd L. Davidson with whom I've just been
    Thats why the actual measurement is of charge 'q'.
    And you are the guy who has just explained that 255 levels of current
    or voltage can be used to carry tone signals. But no, that's not
    digital or digitized. :-(
    That's how the electrical charge is measured.
    If you measure it with sufficient precision you can use it to carry
    digital data.
    Ew've done that bit already.
    But in what form is it whenit is read by the CPU - 12 bit or 14 bit or
    something else again?
    I'm beginning to think you really don't know anything about the logic
    of any of these processes.
    Analog electronic charge. Haw!
    You might be correct if they truly were analog, but they aren't.
    So you keep saying.
    I think the design of sensels has progressed since you helped invent
    them. Their charge can be read with much greater precision than you
    seem to think.
    I know all that. But what does he have to do with this particular
    It takes two to cooperate. Apart from that, I think we are approaching
    this from two different directions. My background includes university
    training in physics, electronics and mathematics. My terminology is
    different from yours (e.g. transform) and so to is my approach to the
    In the case of the D300 I do not think that is the case.
    I'm talking of raw data. Then Nikons apply a characterisation curve to
    the senso data before it is recorded as RAW file data. There is much
    I don't have the information but I am sure the process is reversible
    (Subject to statistical error limitations).
    In his own way, he is.
    How do you think you get a digital display to X significant figures on
    a digital volt meter? Thats the same way that the output of a charge
    amplifier is digitised.
    Boyle and Smith were the inventors of electronic imaging 40 years ago.
    If you were working with electronic imaging 40 years ago you _must_
    have been working with Boyle and Smith.

    Eric Stevens
    Eric Stevens, Jun 3, 2009
  18. ISTM to be relevant to point out that even if no processing of the data
    is required (it is, of course if only to label the format and cell
    layout) - the distribution of colour sensors are different from a tft
    screen and so the RAW 'image' cannot be viewed without interpretation.

    I'll go back to sleep now...


    "I never have taken a picture I've intended.
    They're always better or worse."
    Diane Arbus
    Michael J Davis, Jun 3, 2009
  19. aniramca

    tony cooper Guest

    Ah, this is the step that was not in the previous instructions.
    tony cooper, Jun 3, 2009
  20. Could the two of you, Messrs. Stevens and Davidson, take this offline?

    There is some risk that this thread will become tedious.
    John McWilliams, Jun 3, 2009
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