2 questions regarding Bayer sensors

Discussion in 'Digital Photography' started by Georgette Preddy, Jun 2, 2004.

  1. Georgette Preddy

    Bill Funk Guest

    The Foveon sensor does not have a native 13+MP output; no way, no how.
    The Sigma ED9/10 cameras do, but that's a result of upsizing, and has
    nothing to do with the Foveon sensor's size or native pixel output.
     
    Bill Funk, Jun 8, 2004
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  2. Well at least they are able to trick some naive consumers, such as GP, into
    believing that the 13.72 MP output has something to do with resolution.
    Perhaps it's morally wrong to allow a sucker to keep his (or her) money.

    I give credit to Canon and Nikon here for not doing something similarly
    misleading. It would not be hard for Canon and Nikon to do upsizing and
    generate larger output files. Why stop at 4X upsizing like Sigma? You could
    do 16X, and fill up your memory card even faster! The problem is that if
    Canon or Nikon did something like this, someone might take notice and
    contact the FTC, with Sigma, there's no one there to care. Still, I'm going
    to shoot off a letter to the FTC.

    It reminds me of the audio component manufacturers that used to use
    "Instantaneous Peak Power" in power ratings, rather than RMS. It tricked
    some people, at least for a while, then there were rules put in place to
    stop the misleading advertising.

    Perhaps the government needs to set legal definitions of camera resolution
    to stop the Foveon/Sigma shenannigans. If either had any market share, the
    other companies might object to it all, but it's not an issue for now.

    The camera review web sites already make it pretty clear that Sigma and
    Foveon are being less than forthright when they try to equate photosensors
    to spatial pixels.
     
    Steven M. Scharf, Jun 9, 2004
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  3. Mr Scharf is learning from George P. First, the camera does nothing at
    all to upsize files. Not a thing. Secondly, the software only offers 2X
    resizing, not 4X and never has.

    And if Canon and Nikon do NOT offer upsampling from RAW files, they are
    behind Minolta (who do, in their Dimage Viewer application) and also
    behind Adobe, who offer this as a function for all digital cameras - it
    varies according to the type, and they do not support a full 2X with the
    Sigma file, only a scale up to around 1.5X.

    Nor do Sigma or Foveon anywhere on the camera claim the 13.7 megapixels
    figure which sic-Preddy has put about. They do have a 10.x sticker on
    the camera, and should not. It's misleading.

    But not half as misleading as Steven Scharf, who really should have been
    put in charge in Iraq.

    '25 Reasons we Know there are Weapons of Mass Destruction...'

    David
     
    David Kilpatrick, Jun 9, 2004
  4. This is not entirely fair. Music is seldom a compact output
    at max volume, it has some dynamics. So, if you can supply
    extra power for some few seconds or even milliseconds, you
    can get a much better sound. So - there is lots of totally
    respectable audio equipment makers that present both RMS
    and peak power.

    On the other hand, those dishonest PC speaker makers that
    claim that they can get 750 W out of a speaker that is powered
    by a simple AC adaptor. Thats lies for sure. You are lucky
    if those speakers give you 7.5 W, more likely 0.75 W RMS.


    /Roland
     
    Roland Karlsson, Jun 9, 2004
  5. True, but it's worth noting that there are honest and dishonest ways of
    measuring peak power. If an amplifier will deliver 100 W continuous all
    day, and will also deliver 200 W of sine wave for a specified number of
    milliseconds (at least several cycles of the sine wave), then it's
    reasonable to say it will do 200 W peak. I think there's even an IHF
    standard for measuring this headroom.

    On the other hand, in the bad old days it was sometimes obvious that the
    "peak power" was not the average over one sine wave cycle, it was the
    instantaneous power for a point sample at the peak of the sine wave.
    Or it might have been the peak power available from a pulse input.
    It had to be calculated this way, because the number was essentially
    equal to the unloaded power supply voltage applied across an 8 ohm
    resistor. This kind of "peak" is 2 or more times what the amplifier can
    actually deliver averaged over 1 cycle of sine wave.

    Dave
     
    Dave Martindale, Jun 9, 2004
  6. Georgette Preddy

    bagal Guest

    isn't there a well defined (in electronic terms) RMS root mean square value
    in all this?

    db
     
    bagal, Jun 9, 2004
  7. SNIP And this is the correct comparision,
    <http://www.xs4all.nl/~bvdwolf/main/downloads/AoR.png>

    when one doesn't try to fool the Bayer CFA by forcing different output
    magnification as you can see here:
    <http://www.xs4all.nl/~bvdwolf/main/downloads/SD-9_identical_FoV_to_1Ds.jpg>

    Bart
     
    Bart van der Wolf, Jun 9, 2004
  8. SNIP
    No they don't. They show what happens if you magnify a very small part of
    one sensor and compare it to a much larger part of another sensor.
    <http://www.xs4all.nl/~bvdwolf/main/downloads/AoR.png>

    Bart
     
    Bart van der Wolf, Jun 9, 2004
  9. SNIP
    LSD?

    Bart
     
    Bart van der Wolf, Jun 9, 2004
  10. Georgette Preddy

    bagal Guest

    lol - no, there are some serious philosphical questions associated with
    evolution though

    for example, why have we evolved not to see uv?
     
    bagal, Jun 10, 2004
  11. If you bought a Bayer based on MPs, you were fooled. Bayer MPs are
    strictly monochrome, not color MPs. Bayer color must be digitally
    simulated by combining sets of 4 monochrome sensors to create each
    discrete color pixel.

    Bayer MPs/4 = color MPs.

    Foveon has color MPs.
    Like most, you missed the scam there too. Power rating alone is
    utterly meaningless, power per unit distortion is meaningful. You got
    screwed again.
    Already done, Sigma/Foveon are the only manufacturers that conform,
    all others are in direct violation for listed interpolated-color
    resolutions as 100% optical resolutions.
     
    George Preddy, Jun 10, 2004
  12. Georgette Preddy

    tekfull Guest

    where are your pics


     
    tekfull, Jun 10, 2004
  13. It shows what happens when you spread a very small number of optical
    sensors over a larger sensor area, optical resolution tanks.

    The SD9 blows the Canon 1Ds off the face of the Earth on optical
    resolution, the 1Ds can recover a fraction of that huge disadvantage
    by using a stronger zoom as a handicap.

    Other problem is, the 1Ds has a way too small a sensor pitch and uses
    very old CMOS fabrication technology (486-vintage), so noise is also
    very high. Foveon's sensor pitch is 20% bigger, even after its
    whopping 25% percent higher color MP count than the 1Ds, and smaller
    sensor area, due to the miracle of spreading out into 3 dimensions,
    vice only 2 for the aged Canon.
     
    George Preddy, Jun 10, 2004
  14. Georgette Preddy

    tekfull Guest

    Where are your pics gp


     
    tekfull, Jun 10, 2004
  15. Yes and no.

    Strictly speaking, what you care about is the mean (average) power of
    the sine-wave output signal, either sustained for many minutes, or for
    at least a few cycles depending on whether you're measuring steady or
    peak power. If you have a meter that reads directly in watts (they
    exist), you just want average watts. No RMS necessarily involved.

    However, the usual way to measure power is to make the load a resistor
    of known value (usually 8 ohms). In that circumstance, the
    instantaneous power is simply the voltage squared divided by the
    resistance (V^2/R), and voltage is easy to measure with an oscilloscope.
    Alternately, you can measure current delivered to the load, and
    instantaneous power is current squared times the load resistance
    (I^2*R). Again, this is easier to measure than true power.

    But voltage and current change with time, and you want average power
    over some span of time. Since instantaneous power is proportional to
    the square of voltage or the square of current, you need to use the
    root-mean-square voltage or current in order to get the right answer.
    So:

    average power = V(RMS)^2 / R = A(RMS)^2 * R

    Using average voltage or peak voltage in these calculations will not
    give mean power.

    A bit of thought shows why RMS voltage/current is correct: If you
    square the instantaneous voltage readings, you get a number proportional
    to instantaneous power. Then you average those values, giving a number
    proportional to mean power. Then you take the square root, so the
    final number is in units of volts.

    Another use for RMS voltage: a resistive heater (toaster, clothes iron,
    hair dryer, etc.) plugged into a 120 VRMS sine wave source provides
    exactly the same amount of heat as the same heater connected to 120 VDC.
    So RMS voltage is the "DC equivalent" voltage, even though the peak
    voltage is about 170 V and the mean voltage is something else again.

    Finally, you'll often see discussions of amplifiers and speakers talking
    about "RMS power". That's a nonsense term. What they mean is *mean
    power* measured using RMS voltage. Root-mean-square power is
    well-defined physically, but it just isn't an interesting measurement
    for anything practical.

    Dave
     
    Dave Martindale, Jun 10, 2004
  16. Georgette Preddy

    Lionel Guest

    Yes. That's the official definition of 'countinuous output power'.
    Honest amplifier makers list it on their brochures & spec sheets. eg:
    "100W RMS continuous per channel into 8 ohm loads", or some similar
    phrase. (The impedance of the speakers affects the maximum output power,
    so you need to know the power into 8 ohms to make meaningful comparisons
    between amps.) "Watts MP" or "Watts PMP (peak music power)" are mostly
    marketing bullshit, & can be ignored.
     
    Lionel, Jun 10, 2004
  17. Georgette Preddy

    Lionel Guest

    Kibo informs me that (Georgette Preddy)
    stated that:
    No, it isn't. Your ignorant claim directly contradicts everything
    science knows about the way that the human eye works. Given your abysmal
    stupidity regarding just about everything you comment on, I think most
    people will prefer to take the word of several generations of scientists
    over yours.
     
    Lionel, Jun 10, 2004
  18. Georgette Preddy

    Lionel Guest

    Kibo informs me that (Georgette Preddy)
    stated that:
    What do you think a black & white photo or TV uses, you moron? Both use
    pure luminance data only. According to your ignorant arguments, B&W
    images have *NO* resolution.
     
    Lionel, Jun 10, 2004
  19. Georgette Preddy

    JPS Guest

    In message <>,
    By that logic, DSLRs have a handicap over P&S digital because they use
    longer focal lengths for the same angle of view. Do you *ever* think
    about what you write?
    --
     
    JPS, Jun 10, 2004
  20. Georgette Preddy

    Big Bill Guest

    I've noticed that yu ignore the facts when presented.
    Both Bayer and Foveon sensors are monochromatic; it's not until the
    output from the sesors is processed that what we see as color is added
    to the file.
    The sensors output electricity, which does not have color.

    Bill Funk
    Change "g" to "a"
     
    Big Bill, Jun 10, 2004
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