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Brightness and Contrast

The monitor's Brightness and Contrast settings are set at 77% and 50%, respectively, by default. I achieved the reference 100-nit level of white by choosing 30% Brightness and 44% Contrast. The monitor controls its brightness by means of pulse-width modulation of the power of the backlight lamps at a frequency of 238 Hz. It is always set at the maximum in 3D mode so that the flickering of the lamps didn’t combine with the switching of the 3D glasses’ lenses.

 

The monitor has typical brightness and contrast ratio parameters as today's products go. I would only wish the maximum brightness were as high as 300-350 nits. 3D glasses absorb quite a lot of light, so the screen looks darker in them than when you look at it in 2D mode without the glasses. 3D monitors do need some more brightness than ordinary models.

 

The screen brightness varies from 134 to 250 nits in the preset Empowering Technology modes. It must be noted that 134 nits is rather too high for working in text-based applications even under bright office lighting. In a home environment, you may even want to lower the screen brightness to 70-80 nits to avoid staining your eyes.

Backlight Uniformity

The average nonuniformity of black brightness is 5.5% with a maximum deflection of 17.7%. For white brightness, the average and maximum are 6.5% and 15.5%, respectively. These are good results.

Color Accuracy: Gamma, Temperature, Gamut

The monitor has too much contrast at ordinary settings: this is how the eye perceives the too high gamma which is indicated by the sagging color curves in the diagram.

The image only gets worse when you switch into the special Graphics mode: red and green remain intact whereas the blue curve sags even more. The overall effect is that the image becomes warmer and greener. Acer’s engineers believe that such colors look better but I don’t think these image-enhancing technologies will be appreciated by users who prefer natural colors.

The graphs above indicate that the image is too greenish. I corrected this in the User mode by choosing R=94, G=92 and B=100. The result is a color temperature of near 6500 K and a rather accurate gray without any unwanted toning.

These numbers are only correct for my sample of this monitor. Another sample may be set up differently at the factory and will call for different correction. However, if you note your GD245HQ to be somewhat greenish, you may try to set it up as I did in the previous paragraph.

The monitor’s color gamut coincides with the sRGB color space in blues and is larger than it in greens and reds.

 
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