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REVIEW: Eizo CG246 Part 4


Image quality/signal processing

General considerations

The Eizo CG246 is based on a 24-inch IPS panel with LED backlighting. This is as much information as the data sheet would reveal. When queried for more details, Eizo merely stated that the display panel was not manufactured by LG. We were not able to garner any further specifics. Of course, this is perfectly understandable and ultimately of no consequence to the user. Nevertheless, we don’t want to keep our advance guesswork from you, so this is what our measurement results and feature analysis initially suggested:

LG’s state-of-the-art LM240WU9 can optionally be fitted with a GB-r LED backlight. As the naming convention suggests, this means that green and blue LEDs – fitted with a special (red) coating – are being used. In contrast to classic RGB LED backlights, which are expensive and difficult to integrate, this new design does not need to be installed flat behind the panel. As a result, the light yield is much higher. Nevertheless, the gamut is as wide as for monitors based on WCG CCFL tubes without requiring the panel filters to be refined. Ultimately, this innovative approach may well mean the end for CCFL-based backlights.

Such a combination of display panel and backlight would have fitted the CG246’s specs perfectly – ‘would have’, had we not heard otherwise from Eizo themselves. Naturally, we have no reason to doubt them. The most obvious assumption, as it turns out, isn’t necessarily the right one. Another feasible possibility for this monitor would be a rather exclusive PLS panel from Samsung, but again this is pure guesswork, as we are not permitted to take our test units apart.

The rest of the manufacturer’s data indicates that the Eizo CG246 is a true high-end model: The programmable 16-bit 3D LUT prevents tonal value losses from the source signal and forms the basis for an accurate display. For the colour channels to be reduced to the standard 8-bit output, an FRC dithering algorithm is used that works unobtrusively in the background. No matter what the OSD settings were, our practical tests showed no tonal breaks whatsoever in any colour gradients. This was also true after recalibrating the hardware.

The DisplayPort input can be used to reproduce signals with 10 bits per colour channel. This requires a suitable graphics board, operating system, driver and host application; currently, there are only very few setups that do this well. Given the right source system, the current version of Adobe Photoshop worked faultlessly in this regard.

Test image for checking greyscales

Subjective testing of the image quality revealed no flaws. All of the predefined image modes are implemented fastidiously and produce convincing results. The inherent contrast limitations of the IPS panel do not have any negative repercussions for CEPS work. This is also due to the wide viewing angle provided for black content (see ‘Viewing angle’). An added plus: The panel is fitted with a subtle yet highly effective anti-glare coating. The typical anti-glare sparkle found on IPS panels is eliminated almost completely, yet there are no strong reflections that might affect the image quality.

Interpolation

The Eizo CG246 coped well with scaling our test signals. Thanks to a seven-step ‘Outline Enhancer’, the display can be individually adapted. With the two highest settings, some slight double contours could be detected.

If the source is received via the DVI or DisplayPort input, any signal with a square pixel aspect ratio can optionally be displayed without distortion. This settings change automatically when the HDMI input is selected. Separate settings for 4:3 and 16:9 are provided to ensure the correct display of SD sources. Another setting is reserved for letterbox-format sources; this crops the signal and scales it to full screen.

Scaling tests.

Source signal Undistorted display Unscaled display Description
SD (16:9 - anamorphic) yes no HDMI
SD (4:3) yes no HDMI
HD (1080p) yes yes DVI, DP, HDMI
HD (720p) yes yes DVI, DP, HDMI
PC (5:4) yes yes DVI, DP
PC (4:3) yes yes DVI, DP, HDMI
PC (16:10) yes yes DVI, DP
PC (16:9) yes yes DVI, DP, HDMI

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3 Comments available


Thanks for this review, I bought this display, by far the best one I've owned.
I'd need an information: I 'm about to buy a device that use hdmi to output a 10bit video signal, but only dp is 10 bit in the 246; so is enough to use a hdmi/dp cable or adapter or I'll have 8 bit signal?

sam
I'm unable to guarantee that. You will need a HDMI to DisplayPort converter - not a simple cable - because of different protocols used. A 10bit workflow is in principle not a problem but it depends on the capabilities of this converter.
Perfect, I'll look for a proper converter,
thanks a lot

best regards
sam

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