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Discussion in 'General Electronics Discussion' started by cradlemess, Aug 5, 2009.

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  1. cradlemess

    cradlemess

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    Aug 5, 2009
    Sirs / Ma'ams

    What's the maximum allowable speed of a moving object for a standard cameraphone (nokia N-series??) be able to capture? Can it be seen in the phone's specifications? If so what specification should i look in to? :confused:
     
  2. Resqueline

    Resqueline

    2,848
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    Jul 31, 2009
    If by "capture" you mean "sharp" as in not being blurred then the spec that would say someting about that is Shutter Speed. It could be anything from 1/60 to 1/1000 of a second. Lower fractions are of course better in this respect (but requires better light).
    I have never looked for such spec's in cell phones so I can't say if you'll find it.
    The actual practical results (in terms of speed) will of course depend on the lens's field of view, the distance to the object, & its angle of approach relative to the lens.
     
  3. jasonben

    jasonben

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    Jul 15, 2009
    I imagine that if the object is spinning then symmetry might be a factor too. If information describing the appearance of the object – perhaps in relation to a background, is ever included in specifications, how is it described and related? How detailed can these kinds of specs – not just for camera phones but for all imaging systems, get?
     
  4. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    A moving (or spinning) object may get distorted by the scanning action of the readout process from the imaging chip.
    But the only spec's I can imagine is ever needed with regards to this capture issue is Shutter Speed, Focal Length (or Field of View) and Response Time (from you press the button till the picture is actually taken).
    With these three at hand it's only up to the users education to calculate if it's good enough for his intended use.
    This also equally applies to video cameras. Many video cameras have a "sports" setting which shortens the Shutter Speed drastically and "freezes" movement.
     
  5. cradlemess

    cradlemess

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    Aug 5, 2009
    what if the moving object of interest is about an inch in size, say a barcode? will those 3 factors be enough as basis for it's detection?
     
    Last edited: Aug 22, 2009
  6. jasonben

    jasonben

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    Jul 15, 2009
    Is it the part of the circuit that is sensing the image and sending signals about the image or the part of the circuit that is reading and processing the signals from the sensing part of the imaging device that is slower? How are the signals from the sensors to processor organized? By color, location? Which signals - containing color information; location information; or something else, is sent first from the area associated with the sensors to the area associated with the processor? Is information about some locations sent before information about other locations? Is information about some colors sent before information about other colors?
     
    Last edited: Aug 11, 2009
  7. jasonben

    jasonben

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    Jul 15, 2009
    I can't answer your question but I'm interested in it. It may be that a blurred image may able to communicate some distinct information about the bar code - depending on the processing system. I can think of a couple of different types of images if there were multiple black or dark gray bars in one code. The image could be precise. The image could be blurred - but the white spaces between the bars identified. There might only be black and gray shapes if the white spaces were "blended" with the bars. These situations may apply if the entire length of the bar code was recorded or just part of the bar code - perhaps depending on the speed that the code was passed over the sensor and the shutter speed - if a shutter was used. Or, all that may be recorded is one blurred gray representation of a single bar - or the white space between two bars. The usefulness of these might depend on some classification of the uniqueness of the code and capabilities of the processing system - if the processing system was a computer. I'm wondering if in some cameras the shutter speed or amount of time that the sensors were activated was calculated by a function relating a detected speed of the first bar or couple of bars sensed or a detected contrast related to the bar code image. Although, I can't think any situations in which this type of technology would be applied to bar code sensors. What are some fast moving similar objects that vary in width? Maybe such an imaging system could be attached to a horizontal projectile to inventory trees in a forest.
     
  8. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    With a barcode you have definite thicknesses of the lines to use as a basis for determining how much movement (blur) is tolerated before it gets unreadable. From there on it's simple calculus to convert it to time. You hardly even need trigonometry.
    Obviously, if the barcode moves vertically the tolerated speed will be greatly increased compared to horizontal movement.
     
  9. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    Come on, why don't you just read up on CCD chips? It won't take much to learn more than I know..
    The shutter thing in the chip (no, I don't know how it actually works on cip level) has to be the fastest. Then comes the readout process that takes pixel by pixel (RGBRGBRGB), line by line, just like a TV-scan. Then comes the processing of the picture (contrast enhancement, gamma correction, jpg compression). Finally the storing process.
     
  10. jasonben

    jasonben

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    Jul 15, 2009
    I've researched chips before and got discouraged. The information that I found was more about specs then how they work. Actually, that was what I was looking for at the time - specs. CCD seems as though it might be a very useful keyword.
     
  11. cradlemess

    cradlemess

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    Aug 5, 2009
    sir, why is it that i can not see a shutter speed rating on cameraphones specs? or is it that i'm not looking hard enough?
     
  12. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    Basically yes. Googling for cameraphone shutter speed would have given you 26000 hits.
    But I guess the reason manufacturers up till now might have been reluctant to present that information up front is that the cameras in the phones have been of insuficient quality to make it something to brag about, and the "only" people concerned with shutter speed are "pro" photographers that "knows" that cameraphoones are inferior and not to be used when performance matters.
    For instance, I just now learned that the fastest shutter speed of the Nokia 6220 is 1/33 of a second. Thats hidously slow and neccessitates a very steady hand to get sharp images.
     
  13. jasonben

    jasonben

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    Jul 15, 2009
    Is that because cameraphone consumers just aren't interested, the technology involved in higher quality image production is not as compact, or a completely different technology - that is either too expensive or unpopular, would be involved in improving cameraphone images?
     
  14. cradlemess

    cradlemess

    10
    0
    Aug 5, 2009
    sir resqueline,

    thanks for your answers :)

    i might ask more questions later on
     
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