Display Testing and Conclusion
Uncalibrated results show colors slightly outside the sRGB range, but very close. Subjectively the panel did look very good out of the box, but I wanted to see if there was room for improvement for any color accurate work. I used the relatively affordable Datacolor Spyder4Pro colorimeter (superseded by the Spyder5Pro), which would add $149 to the cost of this monitor. So is the calibrated result worth the added investment?
I first calibrated the PB258Q at the 120 cd/m2 brightness recommended for the measured ambient light in my room. However as this brightness level only requires a 20% backlight setting overall grayscale accuracy wasn't as high as I would have liked. Post calibration the color had a more natural balance with a slightly warmer tone (the calibration target was 5800K) and better black levels.
I re-ran the calibration at 50% backlight level (224 cd/m2), and the results up to 50% backlight were very good. The calibrated result wasn't too bright at this higher level, so I left it at this higher setting against the recommendation of the Datacolor software.
The 99% sRGB result from the Spyder4Pro comes as close to confirming the advertised 100% spec as I would have expected from this mid-range consumer colorimeter.
Finally, here's a look at the measured brightness and contrast at various backlight levels. The contrast numbers might seem low, but these are typical of IPS without any kind of dynamic contrast control enabled.
Viewing angles were excellent from the IPS panel in the PB258Q, as was backlight uniformity.
No, this isn't a blank photo. Just extremely good black levels
If you look closely there is a slight bleed at the top of the display, but overall very good black levels (I had to boost the brightness quite a bit to make it visible in the photo). I've used far more expensive IPS panels with far higher black levels and noticable edge/corner bleed, and this impressed me with its lack of clouding and very minor bleed.
While a striking design, the PB258Q does have a bezel hiding under the matte finish screen. The panel is recessed slightly (around 1/4") which is immediately visible with the display powered up.
I didn't mind this, since the "frameless" design wasn't the reason I selected this monitor anyway. Just be aware that there really is a bezel, even if it is invisible with the power off.
Advertised as a frameless monitor, the design of the PB258Q is actually more impressive-looking when the display is off. The LCD panel actually resides about 1/4” inside the edges, making the "frameless" style vanish when it's powered up. But it’s the quality of the IPS display that really makes this monitor stand out. A 2560×1440 IPS display with accurate color and a fully adjustable stand, readily available for under $400, creates a compelling option in a crowded display market.
The compact 25-inch size is unusual for a WQHD display, and coupled with the extremely narrow bezels (frameless or not) this won’t take up much space on a desk. An added benefit of the smaller size is that text looks particularly crisp, making this great for productivity, and the matte finish screen and flicker-free backlight allows for longer sessions without eye strain (and there are several low blue light modes as well).
I can easily forgive the variance in grayscale accuracy based on backlight level as we are still talking about a $377 monitor, and the performance and overall build quality make it seem like a much more expensive part. It’s been my daily driver since day one and overall I highly recommend the PB258Q.