Colorimeter measurements corrected from spectral readings

Late yesterday night, I completed the math and code to adjust my display high precision colorimeter measurements with spectral readings taken with a spectrophotometer.

During #MWC15 , I was going booth to booth with both a X-Rite I1 Display Pro colorimeter, that's particularly quick and a EFI-ES1000 spectrophotometer (same as a X-Rite i1 Pro), connected alternatively to the tablet running my software.

The spectrophotometer is about 3 times slower, but has the merit to see the light wavelengths intensities while the colorimeter uses some kind of RGB sensor that's able to tell the real colors only if their spectral characteristics match what it has been optimized for.

The correction logic was not implemented until now, so here are graphs from a +HTC One M9 unit, before and after correction.

Not only the spectrophotometer doesn't see the same thing, but these measurement confirm why you've heard reviewers mentioning a ''green tint" on the M9.
It's indeed here, and our eyes are very sensitive to an excess of green. We tend to be less bothered by wrong amounts of red and blue however. The M9 display also has too much blue and not enough red.

#progress #supercurioBlog #color #display #calibration #development

     

In Album Have correction from spectral readings now

Source post on Google+

Published by

François Simond

Mobile engineer & analyst specialized in, display, camera color calibration, audio tuning

26 thoughts on “Colorimeter measurements corrected from spectral readings”

  1. None of those results are good I'm afraid, but I'll develop that in an article to come.
    It shows the necessity to use a spectrophotometer however, as the colorimeter alone sees too much blue and also hues a bit off for all three color primaries.
    That's why I attached CIE Diagram, temperature and RGB levels graphs without and with correction so you can see the difference.

  2. None of those results are good I'm afraid, but I'll develop that in an article to come.
    It shows the necessity to use a spectrophotometer however, as the colorimeter alone sees too much blue and also hues a bit off for all three color primaries.
    That's why I attached CIE Diagram, temperature and RGB levels graphs without and with correction so you can see the difference.

  3. +Mark Stronge there's nothing to be enthusiast for in the data shown here mate.
    The only thing that's not poor compared to things we've seen before is that they didn't boost the color saturation unreasonably.
    But given how the white point is off (too much blue and green), warm tones looks muted and cold.
    Again, I'll develop that in an article 😉

  4. +Mark Stronge there's nothing to be enthusiast for in the data shown here mate.
    The only thing that's not poor compared to things we've seen before is that they didn't boost the color saturation unreasonably.
    But given how the white point is off (too much blue and green), warm tones looks muted and cold.
    Again, I'll develop that in an article 😉

  5. I noticed that many display manufacturers tend to be more on the blueish side even though making a good white point would've been possible. Is it possible that they do this so the screen can get brighter?

  6. I noticed that many display manufacturers tend to be more on the blueish side even though making a good white point would've been possible. Is it possible that they do this so the screen can get brighter?

  7. +Flo Frrokaj yes absolutely, one reason why many LCDs have too much blue and not enough blue is because it is closer to the native white point of the panel, resulting of the backlight color temperature and nature of RGB filters.

    However, on most panels it is perfectly possible to get a satisfying white point without crippling the contrast ratio, maximum brightness or power efficiency.
    I'm not entirely convinced +HTC made the best job they could here, even if they were aiming at maximizing the power efficiency.

  8. +Flo Frrokaj yes absolutely, one reason why many LCDs have too much blue and not enough blue is because it is closer to the native white point of the panel, resulting of the backlight color temperature and nature of RGB filters.

    However, on most panels it is perfectly possible to get a satisfying white point without crippling the contrast ratio, maximum brightness or power efficiency.
    I'm not entirely convinced +HTC made the best job they could here, even if they were aiming at maximizing the power efficiency.

  9. +François Simond Sony did the same thing with the Z3 series but I kind of like the effect since it still has a pretty wide gamut. But don't like the blacks on the Z3 they are just not punchy enough in my opinion.

    Speaking of color accuracy, could you recommend me a 1080p monitor for my laptop? I visit a media design school and I cannot work properly on my laptop screen. It's a low-resolution tft display with terrible viewing angles and it's not able to show full sRGB. Also some of the pixels are already dead. 200€ would be the maximum price, I don't care about the display size… Is there anything you can recommend in terms of color accuracy?

  10. +François Simond Sony did the same thing with the Z3 series but I kind of like the effect since it still has a pretty wide gamut. But don't like the blacks on the Z3 they are just not punchy enough in my opinion.

    Speaking of color accuracy, could you recommend me a 1080p monitor for my laptop? I visit a media design school and I cannot work properly on my laptop screen. It's a low-resolution tft display with terrible viewing angles and it's not able to show full sRGB. Also some of the pixels are already dead. 200€ would be the maximum price, I don't care about the display size… Is there anything you can recommend in terms of color accuracy?

  11. +Flo Frrokaj yes, the Z2 panel power efficiency was not good enough and also people were complaining about the outdoor readability, so they changed the filters and phosphors to let a lot more blue go through and reduce the gamut a bit in order to increase the overall luminous efficacy.
    Meaning: higher perceived brightness for the same power consumption.

  12. +Flo Frrokaj yes, the Z2 panel power efficiency was not good enough and also people were complaining about the outdoor readability, so they changed the filters and phosphors to let a lot more blue go through and reduce the gamut a bit in order to increase the overall luminous efficacy.
    Meaning: higher perceived brightness for the same power consumption.

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