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Thread: Calibrating laptop monitors

  1. #1

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    Calibrating laptop monitors

    I read somewhere that it is not possible to calibrate an digital TFT monitor. I have a 19 inch flat screen monotor attached to my laptop. It is set up in the digital(DVI) mode. Obviously, it is possible to tilt the monitor through a wide range of viewing angles thereby changing the viewed color quality. This particular monitor is not lockable in any one position. Under these conditions is it possible to calibrate this monitor sucessfully
    Any ideas will be welcome.
    Paul

  2. #2
    McQ
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    Re: Calibrating laptop monitors

    Hi Paul. You can certainly calibrate a laptop monitor, but you just have to be aware of the limitations. The two biggest concerns that come to mind include:

    (1) The limited viewing angle of your particular laptop (as you point out)
    This does not mean that you cannot therefore calibrate this display. All this means is that you need to view your monitor under the same conditions in which it was calibrated, if doing color critical work. In other words: 90 degrees straight on. In my mind, the viewing angle limitation should be no means prohibit you from trying out a calibration, or even achieving a decent calibrated result.

    (2) The limited 8-bit LUT (look-up table) of most LCD monitors (laptops in particular)
    The LUT represents the palette of colors from which your monitor has to choose from when creating an image. If you calibrate this monitor using a calibration device, it will correctly determine the inaccuracies in your display's color just like with any other monitor. The real problem arises with the correction step. Even though the calibration device is able to tell your video card and monitor the correct colors, monitors with 8-bit look-up tables are only able to choose discrete values between 0-255 for each red, green and blue channel. If your calibration device has determined that the true grayscale tone should be somewhere between 12 and 13 for R,G,B on your monitor, then your monitor has no other choice but to round to the nearest number. Depending on how accurate your display is to begin with, the visible difference between a 12 and a 13 can be pretty large. This "rounding error" can introduce image/tonal posterization, which is a big problem for color critical work.

    Further, if your laptop monitor's colors are way off to begin with (as many laptops are), then the posterization effect can become very pronounced. You will often see slight color hues in areas of an image that should otherwise be purely grayscale. For laptop displays and other LCD's, this effect is often worst in the shadow tones.


    Overall, it doesn't hurt to give the calibration a try if you already have a device. You can always revert back to your monitor's native colors if you do not like the result. Just be sure to remember any substantial changes in the calibrated display (versus uncalibrated), so that in your mind you can compensate when printing images. For example, if the calibrated display reduced contrast dramatically, then just be aware that printed images will likely look much less contrasty than on the monitor. Alternatively, if the calibrated display made the red more saturated, just know that they'll be more saturated in print.
    Last edited by McQ; 20th February 2009 at 09:22 PM.

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    Re: Calibrating laptop monitors

    Hi Paul,

    Just keep in mind though that any posterization etc due to the limitations of the laptop screen & associated circuitry doesn't affect the printed image, just the displaying of it on the screen.

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    Re: Calibrating laptop monitors

    Thanks for your quick and informative responses. I may have inadvertantly mislead you. The monitor I referred to is a stand alone 19" HP flat screen monitor and not part of my laptop, although connected to it. Also, the ATI graphics programme operates a 32 bit color quality system. I don't know if this is significant. I am getting into areas here which I find a little confusing. This will soon lead me to seeking advice on printer control with PS Elements7.

    Thanks again,
    Paul

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    McQ
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    Re: Calibrating laptop monitors

    If this is a flat panel / LCD monitor then the above discussion still applies. Generally speaking, the only real difference is that you might expect slightly better calibration results than if it were a built-in laptop display. However, I do want to make sure that you are not talking about a flat screen CRT, which would be the older kind of display that is much thicker in the back.

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    Re: Calibrating laptop monitors

    The referenced monitor if definitely not a flat screen CRT. It is a liquid crystal display which is the same as the laptop monitor.
    Thanks again,
    Paul

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    Re: Calibrating laptop monitors

    Can I ask which brand you guys recommend for the calibration device?

    Thanks,

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    Re: Calibrating laptop monitors

    Quote Originally Posted by sedali View Post
    Can I ask which brand you guys recommend for the calibration device?
    I use a Spyder III as part of Colorvision's Elite package. Software is a bit clunky (although many like it) - and it gets the job done.

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