Computer monitors

Discussion in 'Digital Photography' started by m Ransley, Dec 11, 2005.

  1. m Ransley

    Ray Fischer Guest

    Who cares about your book?
     
    Ray Fischer, Dec 14, 2005
    #81
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  2. [A complimentary Cc of this posting was sent to
    David J Taylor
    I do not think any printer can get better than 50:1; doing better than
    100:1 with reflective media is very hard. Best CRT's have
    "theoretical" dynamic range of 30000:1; a well set up consumer unit
    should easily get about 10000.

    The problem with CRT is, first, that this dynamic range assumes very
    special "dark room" environment. Second (and main) is that this is
    the dynamic range of "fully dark screen" vs "fully bright screen"; if
    you have a dark area near the bright area, due to internal reflection
    the dark area is strongly contaminated. IIRC, on high spacial
    frequencies the dynamic range may be as low as 5:1.

    For details, see wonderful review (very long):

    http://www.extremetech.com/article2/0,1558,1734380,00.asp

    and the continuations.

    Hope this helps,
    Ilya
     
    Ilya Zakharevich, Dec 15, 2005
    #82
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  3. m Ransley

    Ray Fischer Guest

    Assuming the conclusion. You're assuming that there are pixels in
    order to argue that there rae pixels.

    The CRT doesn't do pixels. They exist only in the computer.
    Idiot.
     
    Ray Fischer, Dec 15, 2005
    #83
  4. m Ransley

    Ray Fischer Guest

    There is no pixel on a CRT.
     
    Ray Fischer, Dec 15, 2005
    #84
  5. m Ransley

    miso Guest

    Er, the BNC is alive and well, thank you very much. Besides being found
    on most radio gear, the BNC is the mainstay of test equipment. Just
    about every piece of test equipment I own has a BNC.

    The D-sub is cheap. That is why it is used. Also, you would have a
    hard time getting 5 BNCs on a video card.

    The terminals that use BNCs have bandwidths around 300Mhz. The 445Xpro
    I has 270Mhz bandwidth. I think the F930 was a bit above 300, like
    320Mhz. The specs are on the BNC inputs.
     
    miso, Dec 15, 2005
    #85
  6. m Ransley

    Leo Guest


    This is NOT a good definition, since there are actually 2 definitions of pixels
    in computer use. One is the pixel as output from the graphic card, which is a
    'colored dot'. This dot is referenced only to RGB content, not shape.

    The other is the pixel as used in the display, which may be 3 colored circles,
    or squares, or as used by Trinitron tubes, 'defined line areas', since the
    phosphor consists of continuous vertical lines. The beam lights up anything it
    hits. In an LCD, you can't just light up the corner of a 'pixel', you must light
    the whole thing.

    These have more definition then other types, including LCD, since the line has
    no vertical limit. The area between phosphor areas is black and cuts the
    brightness of the image. The old RCA tri-dot tube is the dimmest, and still very
    popular. Most of the CRTs canvassed in my office today are that type. One was a
    Trinitron, which has far finer areas, and more phosphor then black. The LCD I
    use has squares made up of three vertical lines of color, and at maximum res,
    the 'i' here is exactly 3 lines wide. or 1 pixel wide. If I wanted a colored
    'i' it would get thinner and distorted as the rest of the pixel darkens. The
    Trinitron I also use has twice this resolution, the lines are hard to see with a
    loupe.

    Note that camera sensors use 4 or more colored dots to create a pixel, that is
    converted to 3 colors later. Computers maintain a separation of 3 colors in 24
    or 32 bit files.
     
    Leo, Dec 15, 2005
    #86
  7. The well-designed display will have a minimum spot size covering a
    complete triplet, otherwise colour aliasing effects would be visible.
    Have you even seen a CRT with a spot small enough to illuminate just a
    single colour? I agree with Måns that a single colour does not consitiute
    a pixel.

    What this shows is that, although the CRT is an analog device, there is a
    discrete aspect when an RGB display matrix is added, which gives the
    colour CRT characteristics of both continuous and sampled-data systems.

    David
     
    David J Taylor, Dec 15, 2005
    #87
  8. Ilya,

    I agree with you that at high spatial frequencies the dynamic range may be
    much less, but this should not matter in an optimally configured total
    system where the eye/brain will be the limiting factor. For the low
    dynamic range to be visible at high spatial frequncies, they eye would
    need to be mich closer to the display than it would in normal viewing. I
    imagine that LCDs also have this stray light limitation.

    David
     
    David J Taylor, Dec 15, 2005
    #88
  9. ... but the shadow-mask tube, with RGB triplets, does have a finite number
    of triplets which can display a full-colour image.

    David
     
    David J Taylor, Dec 15, 2005
    #89
  10. That fits precisely into the definition listed above.
    And *that* fits precisely into the definition listed above.

    Just one definition, though you have shown to nice examples.
    The same is true on a CRT. Read the definition. Whatever is
    the "smallest discrete component of an image"...

    A pixel is not a component part of the output from a graphics
    card, it is not a component part of the mask or phosperous on a
    CRT, nor is it a sensor site on a CCD or even one element on an
    LCD screen.

    It is the smallest discrete component part of an *image*.
     
    Floyd Davidson, Dec 15, 2005
    #90
  11. So? Who said anything different? I'm just saying that your
    comments about BNC connectors _used_ _on_ _video_ _monitors_ had no
    significance.
    Precisely. And since that is clearly unnecessary too, it isn't
    being done any more.
    So just how many recently designed monitors use BNC connectors? There
    is *one* overiding reason that you won't find many, if any: They are
    unnecessary. I.e., insignificant.
     
    Floyd Davidson, Dec 15, 2005
    #91
  12. You've obviously gotten into something over your head and you have no
    argument other than gratuitous insults about someone you know nothing
    about. Tsch, tsch.
     
    Floyd Davidson, Dec 15, 2005
    #92
  13. By definition, if they are analog the are continuous.
     
    Floyd Davidson, Dec 15, 2005
    #93
  14. If you do not sync precisely to the CRT screen, the same pixel
    will have varying qualities with each frame. It will be
    position differently, colored differently, and vary in
    intensity.
     
    Floyd Davidson, Dec 15, 2005
    #94
  15. Learn to read. That word is "then", not "there".
    The standard definition of a pixel.
    Learn to read. It does not say *anything* about LCD displays.
    That cannot logically be read as "pixels therefore do not exist
    on a LCD". Note that a pixel is the smallest discrete component
    of an image. LCD's display an image, and therefore do have
    pixels.
    See above.
    It is in fact *precisely* correct. I'll grant it is rather
    simple though...

    Digital refers to something with discrete states, i.e. a finite
    set of states. Analog is characterised by range with a
    continiuously variable set of states.
    Your definition of pixel is faulty. Whatever the electron beam
    turns on *is* a pixel. If you turn it off and on twice as fast
    you simply have twice as many pixels. There is an upper limit
    to the range.

    You *cannot*, by definition, turn the beam off in the middle of
    a pixel.
     
    Floyd Davidson, Dec 15, 2005
    #95
  16. As noted previously, numerous times now, your definition of pixel
    is faulty. Please use a *standard* definition, not something you
    made up to suit your other, equally faulty, concepts.
     
    Floyd Davidson, Dec 15, 2005
    #96
  17. Sigh. Learn to read, it makes discussion much easier, and will
    prevent you from being the names you call others.
    That is a genuinely laughable statement. The effort that goes
    into insuring that a pixel location remains precisely in the
    same spot on the screen is what makes up *most* of the
    electronics in a CRT monitor.
    Yes, you can indeed adjust the sync that you say does not
    exist.
    Nothing you've said so far even hints at such being true.
    Learn to read. A discrete component of an image or picture,
    which happens to be displayed on a CRT for example. Now, it is
    isn't part of the CRT screen that makes up this pixel, just why
    do we use CRT's to display images? What other purpose does it
    have????
     
    Floyd Davidson, Dec 15, 2005
    #97
  18. As I've said before:

    "Go find a good dictionary and don't redefine terms for your own
    purposes."

    pixel

    n : (computer science) the smallest discrete component of an
    image or picture on a CRT screen (usually a colored dot);

    Use standard definitions, not something you find convenient to fit
    into your other misunderstandings.

    Here's another one, which isn't quite as simple as the above, so
    I'd expect you'll have even more difficulty with the significance
    of this,

    pixel: In a raster-scanned imaging system, the smallest
    discrete scanning line sample that can contain
    gray scale information.

    Pretty much says if you turn off and on the beam, that's a
    pixel. A pixel is what you can make the screen display... It
    isn't something that exists only as a physical attribute of the
    screen, or only in the graphics card. It is the functional
    *result* of *all* of that combined.
     
    Floyd Davidson, Dec 15, 2005
    #98
  19. m Ransley

    George Kerby Guest

    Good to see that you're making more friends, Fischer.
    Typical liberal.


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    George Kerby, Dec 15, 2005
    #99
  20. m Ransley

    George Kerby Guest

    He usually does.


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    George Kerby, Dec 15, 2005
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