Monitor calibration question

Discussion in 'Photoshop' started by noblack, Jun 17, 2004.

  1. noblack

    noblack Guest

    I tried to calibrate two CRT monitors (on PCs, at 6500K, gamma 2.2) with
    Colorvision OptiCal Spyder and ran into the same problem. Both are Sony
    Trinitrons, one without separate rgb control and one with.

    With the monitors Contrast set to maximum, it is impossible to adjust
    Brightness (even at its minimum) to bring out true black on the screen.
    After creating a profile at these settings, the white and 18% gray look
    great, but the black appears like a muddy gray. After a good monitor
    calibration, should the full range of tones look good? What can be
    causing my problem? Thanks.
     
    noblack, Jun 17, 2004
    #1
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  2. noblack

    Husky Guest

    On Thu, 17 Jun 2004 11:49:33 GMT, wrote:

    did you try the PSA link on my web page
    http://members.toast.net/cbminfo/bev/index.html any news page link has the same
    link to 'Is your computer color blind'
    Give's you a quick check even before you move past my link. If all looks right,
    there's no need to use the link.
    more pix @ http://members.toast.net/cbminfo/index.html
     
    Husky, Jun 17, 2004
    #2
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  3. noblack

    J Warren Guest

    How old are the monitors? After 3 years or so, it's often difficult to
    get a true black level. I had an aging Sony monitor that had that
    problem. "True black" was a deep midnight blue, and no amount of
    fiddling with the front-panel controls would fix it. I know a bit about
    how monitors work, so I took it apart and tweaked gain and bias
    settings. That got me back to normal for a few months, but then it
    drifted out again. I bought a new monitor. Some pro monitors have built-
    in calibration capability to adjust gain and bias within the monitor.
    This is in contrast to external calibration which can only modify the
    video card's LUTs (which shrinks the gamut).

    Jason
     
    J Warren, Jun 17, 2004
    #3
  4. noblack

    ZONED! Guest

    snip

    Sorry for the eavesdrop, but I cannot find what you speak of.I
    couldn't find a PSA link on
    http://members.toast.net/cbminfo/bev/index.html

    ZONED!
     
    ZONED!, Jun 17, 2004
    #4
  5. noblack

    OceanView Guest

    This may or may not be relevent, but Sonys have a distinctive
    yellow tint that's well known. There's probably a way to correct
    for it, though I'm sure exactly how.
     
    OceanView, Jun 17, 2004
    #5
  6. noblack

    Husky Guest

    Like it says any news page link. then find the PSA for the color blind thing.
    It points to a site dedicated to color adjustment. I just grabbed some of the
    checks for a quick check of my own setup, and decided to add a link back to the
    web site that tells you how.

    more pix @ http://members.toast.net/cbminfo/index.html
     
    Husky, Jun 17, 2004
    #6
  7. noblack

    Toby Guest

    All that's necessary is to have the correct values for the white and black
    points. If the white point is too high with the brightness at minimum bring
    down the contrast and recalibrate. The OptiCal software makes that quite
    easy--it has "Check Black" and "Check White" checkboxes so that you can
    switch between them. If you can manage to set those correctly via the
    Brightness and Contrast controls then the s/w will set the grays and RGB
    values.

    Toby
     
    Toby, Jun 18, 2004
    #7
  8. noblack

    noblack Guest

    noblack, Jun 18, 2004
    #8
  9. noblack

    noblack Guest

    Both Sony Trinitrons are three or more years old. The G500 has a control
    for Image Restoration feature which restores the bias and gain back to
    the original factory settings. It also has a control to adjust the bias
    and gain for each rgb channel. Before running OptiCal, I used Image
    Restoration to restore the bias and gain (bias at 50 for each rgb
    channel, and rgb gain at 95/79/71). When running OptiCal Precal, I
    changed the rgb gain to 93/67/50 to line up the the three channels in
    the bar chart. But I was unable to set the black to be true black.

    Upon reading your post, I lowered the bias to zero, and the black gets
    much better (but still not true black). I'll try to calibrate again with
    this setting.

    How does calibration change a video card's LUT and shrink the gamut? Is
    the shrinkage different on different video card? This has always been
    confusing to me. Thanks.
     
    noblack, Jun 18, 2004
    #9
  10. noblack

    noblack Guest

    Even by lowering Contrast, I still could not get a true black. It may be
    true that OptiCal is "easy" provided that you can set the correct white
    and black points. But getting there is *not* easy, at least not on my
    monitors.
     
    noblack, Jun 18, 2004
    #10
  11. Try the 'Precision' calibration mode instead of 'Standard' then
    if you haven't already tried it. You'll find it under Edit >
    Preferences in OptiCAL.

    As mentioned elsewhere in this thread, it's quite normal that
    Sony monitors (and probably other brands too) are drifting so
    that you suddenly can't get a deep black anymore. I've seen
    it too with my Sony FW900. I didn't dare to take it apart
    though so I delivered it back to the place where I bought it
    and they adjusted it for me.

    It's also worth mentioning that a CRT monitor often is brighter
    for the first half an hour or so. That's why you shouldn't
    calibrate and profile it before it's warm. Some say 45 minutes
    and others say an hour just to make sure that it's warmed up.

    Xpost to: comp.graphics.apps.photoshop and alt.graphics.photoshop.
     
    Thomas G. Madsen, Jun 18, 2004
    #11
  12. SNIP
    Yes, my Trinitron tube (in a Dell casing) did the same, but there is a
    monitor option called "color return" that does a kind of reset when
    activated through its OSD menu. Of course recalibration after that is
    mandatory.
    I can even see a visual difference till 30-45 minutes after switching it on.
    Screensavers can also invoke the need for a new warm-up period.

    Bart
     
    Bart van der Wolf, Jun 18, 2004
    #12
  13. noblack

    ZONED! Guest

    ZONED!, Jun 18, 2004
    #13
  14. It wasn't enough here unfortunately. (I have a reset button on
    the front of my FW900 but it couldn't bring it back).
    Normally a Brightness setting of 25 gave me the right black
    point according to OptiCAL, but suddenly the black point was way
    to bright even with the Brightness set to 0. Even the black boot
    screen during POST, which normally was deep black, had a white
    glow. They have adjusted something inside the monitor (I know
    that because they've made a crack in the casing when they took
    it off. Argh!). After that, the right black point was back at a
    brightness of around 25.
    It still drifts though. It's getting brighter and brighter every
    time I use it but I don't care. It's not my primary monitor
    anymore.
    Me too. That's why I always waited an hour back in the days when
    I calibrated it. I don't do that anymore either.
    True.

    Xpost to: comp.graphics.apps.photoshop and alt.graphics.photoshop.
     
    Thomas G. Madsen, Jun 18, 2004
    #14
  15. noblack

    noblack Guest

    Yes, the monitors do need to be warmed up before calibration.

    I tried to tweak the bias and gain settings on the G500. After playing
    around and lowering them a bit, I was able to get the channel chart in
    PreCal to line up and increase the Brightness setting from min to about
    15. The black gets a little better, but still muddy. Not sure if a tech
    can do any better by getting inside the monitor, nor do I know how long
    it will take before the black gets worse again.

    I then hauled out a lowly old MAG monitor and calibrated it just to see
    if there is a difference. The black is true and rich and the calibration
    is a breeze. This MAG is much older than the three Sony trinitions I had
    trouble with. So much for the brand name. Not sure if the Mitsubishis or
    Viewsonics are any better.
     
    noblack, Jun 20, 2004
    #15
  16. I was just curious as to whether you all have your own Spyder or rent or
    loan these things ? I thought of getting one until I heard the price. These
    babies are expensive!

    Another question: Right now I only have a Samsung TFT Syncmaster to work
    with. How well is colour reproduction on these type of screens ? Are they
    suitable for photowork at all ? I don't have the idea Adobe Gamma can do
    much to my TFT colour reproduction *or I must have been doing things wrong*

    Thx
    Pjotr
     
    Pjotr Wedersteers, Jun 25, 2004
    #16
  17. noblack

    Hecate Guest

    If all you're doing is putting images on the web, it will do. Nothing
    more. If you';re intending to print anything, then it's not good
    enough to get accurate colour repro.
     
    Hecate, Jun 26, 2004
    #17
  18. SyncMaster monitors (both CRT and TFT) usually (but not always) ship with
    "Natural Color" software which works pretty much like Adobe Gamma. It's
    wizard like and it offers you a choice of lighting condition besides the
    standard features (if you can call them that given the fact that these are
    essencial parts of a soft-calib progs, etc, etc).

    Anyway, you should stick to that prog. I'm not sure if Adobe Gamma will
    calibrate TFTs...
     
    Branko Vukelic, Jun 28, 2004
    #18
  19. Thanks for your tip. I checked the Samsung site for something like Natural
    Colour, and all I found was something called MagicTune. Downloaded that
    (21mb) but unfortunately it says: Your screen is not supported.
    I haven't been able to find anything else that looked like a utlity. In the
    default download section all I found were PDF documents.
    I have already emailed Samsung support, but I admit my experience with big
    companies is 98% of mails remain unanswered. So I hope I can find help here!

    Anyone has a (link to a) working colour-display-management-utility for my
    Samsung Syncmaster 191N ? TIA!!!
    Pjotr
     
    Pjotr Wedersteers, Jul 6, 2004
    #19
  20. If your graphic card can adjust gamma, you don't need any additional
    software to callibrate your screen.

    Open http://www.unleash.com/mikec/color/figure01.gif in your browser. Set
    your gamma (through your graphic card software interface, a control panel,
    or whatever) to 1.80 and adjust brightness of your monitor until the strips
    match (you'll have to view them with your eyes half-closed or from a
    distance of 2~3 m, i.e, 6~9 ft). If you pull it off right, you'll have a
    callibrated display. The downside of this method is that no profile is
    produced. But the results are as good as using, for instance, Adobe Gamma.

    You can find more info at:
    http://www.unleash.com/mikec/color/
     
    Branko Vukelic, Jul 6, 2004
    #20
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