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Measurement And Calibration Methodology: How We Test

Asus PQ321Q 4K Monitor Review: Top-Shelf Ultra HD For £2800
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To measure and calibrate monitors, we use an i1Pro spectrophotometer and version 5.1.2 of SpectraCal’s CalMAN software.

For patterns, we employ an AccuPel DVG-5000 video signal generator. This approach removes video cards and drivers from the signal chain, allowing the display to receive true reference patterns. Connections are made via HDMI.

The AccuPel DVG-5000 is capable of generating all types of video signals at any resolution and refresh rate up to 1920x1080 at 60 Hz. It can also display motion patterns to evaluate a monitor's video processing capabilities, with 3D patterns available in every format. This allows us to measure colour and grayscale performance, crosstalk, and ghosting in 3D content via the 3D glasses.

The i1Pro is placed at the centre of the screen (unless we’re measuring uniformity) and sealed against it to block out any ambient light. The Accupel pattern generator (bottom left) is controlled via USB by CalMAN, which is running on the Dell XPS laptop on the right.

Our version of CalMAN Ultimate allows me to design all of the screens and workflows to best suit the purpose at hand. To that end, we’ve created a display review workflow from scratch. This way, we can be sure and collect all the necessary data with a concise and efficient set of measurements.

The charts show us the RGB levels, gamma response, and Delta E error for every brightness point from zero to 100 percent. The table shows us the raw data for each measurement. And the area in the upper-left tells us luminance, average gamma, Delta E, and contrast ratio. The individual charts can be copied to the Windows clipboard to easily create graphics for our reviews.

Every primary and secondary colour is measured at 20, 40, 60, 80, and 100 percent saturation. The colour saturation level is simply the distance from the white point on the CIE chart. You can see the targets moving out from white in a straight line. The further a point is from centre, the greater the saturation until you hit 100 percent at the edge of the gamut triangle. This shows us the display’s response at a cross-section of colour points. Many monitors score well when only the 100 percent saturations are measured. Hitting the targets at the lower saturations is more difficult, and factors into our average Delta E value (which explains why our Delta E values are sometimes higher than those reported by other publications).

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  • 0 Hide
    grebgonebad , 23 January 2014 11:03
    'highest pixel count of any monitor I've reviewed to date'Wait until you get to review this beast then!

    http://connect.dpreview.com/post/5972070381/sharp-shows-8k-tv-prototype

    With an 8k resolution (Yes, that's right, 7680 × 4320 totalling to over 33 million pixels!) on a screen over 80 inches in size you can play one pretty mean game of minesweeper!
  • 0 Hide
    mi1ez , 23 January 2014 21:09
    Quote:
    nine-pin-to-3.5 mm RS-232 adapter
    Is this a typo or does this cable have a serial plug on it?A 3.5mm headphone plug on one end and a serial on the other...
  • 0 Hide
    mi1ez , 23 January 2014 21:13
    Actually, after some extra Googling, it looks like it might be one of those camera-to-SVideo cables?
  • 0 Hide
    markaflias , 23 January 2014 22:40
    UHD or 4K ? 4k is not the same as UHD ^^