BenQ PD3225U Evaluation - Black is Back

The BenQ PD3225U 4K Designer Monitor is new from BenQ in May 2024.

It's particularly note-worthy as the first PD Model to feature an (LG made) 'IPS Black' panel.  More models with this technology will undoubtedly follow.

IPS Black panels offer significantly higher contrast and generally improved performance - better viewing angles, better grey (particularly low grey) accuracy, and a generally more vibrant and real quality to image reproduction.

We've seen similar improvements in much more expensive models - ones designed for professional level video editing, for example - but this is the first time we've seen this sort of display performance come down to the lower price point of the BenQ PD range.

Let's look at the basics first.

We've covered quite a few of the PD monitors recently.

(see several recent articles: https://imagescience.com.au/se...)

...so today we're not going to cover every feature in detail, but rather discuss the most pertinent features and interesting new technologies, and cover the key questions that our customers ask us about these monitors.

The major new feature of the BenQ PD3225U is the IPS Black panel - but how good is it really?

Let's start by looking at monitor designs in a bit more detail.  There are, at time of writing, really three basic ways of achieving flat panel light emitting devices - that is, monitors (AKA TVs etc).   Most of these technologies have come from the TV world, more so than the desktop monitor word, so in general we're talking about the context of watching video primarily in this section.

LCD (AKA LED LCD) - is by far the most common technology.  Essentially, you can think of this as some backlights with filters in front of them to turn that backlight into the coloured pixels you see. 

This design is simple and cost effective, but it has the issue that the backlights are always switched on - they need to be so that the bright parts of an image can be displayed - but this makes shadow control very difficult as you have to effectively design filters that can output the bright colours at the top of the range, but also effectively suppress light at the other end of the range. 

This issue has proved a tough nut to crack, and whilst these types of display excel at high brightnesses, they tend to offer quite poor shadow performance, with observably weak, milky shadows.    Hence the recommendation for LCD TVs as being good in bright rooms.

Traditionally, LCDs use edge lighting - the lights are around the edge of the panel and shine in towards the centre.  Fundamentally this is what has led to so many difficulties with achieving both display uniformity and high quality shadow rendering.

As a step up, we have array lighting with local dimming technologies (AKA array/local-array/Mini-LED). These approaches are variations on the classic LCD approach. Here, the panel is instead lit from the rear by an array (grid) of small LED lights. Each of these lights a zone of pixels, and each zone can (usually) also be turned off completely.

This happens very quickly, instant to instant (thanks to the insanely quick switching behaviour of LED lights) - and can be quite effective in controlling the backlighting, such that bright areas remains bright but dark areas are much darker.

The more zones, the better this works - too few zones and you can get 'blooming' or light leak around bright parts of an image that appear next to darker areas. In recent times, it is common for very small 'Mini-LEDs' to be used, resulting in thousands of very small zones, so this blooming issue becomes less of a problem.

At the other end, we have the OLED type designs - in these, each individual pixel of the display emits it's own light - and each can also be turned on or off individually. This gives so called 'perfect blacks' - i.e. when a pixel it is off, the black is almost 'infinite' - no light is coming out of it at all (of course you may see reflected room light in those inky blacks - hence the recommendation for OLEDs being best in darker environments!). OLEDs also have traditionally struggled to hit the peak brightness points that HDR content is looking for, but they excel in the area of contrast and shadow details (and even with HDR content, the vast bulk of what you are seeing lies in this lower range - which is why OLEDs are the obvious choice for better quality displays in most scenarios).

Micro-LED is effectively a further extension of the Mini-LED approach, such that the LEDs used are so small that each pixel has it's own individual light, effectively bringing the potential of OLED like behaviour (and performance) to the table.

(Of course there are many other aspects and pros and cons to each type of design - this is by no means the whole story!)

Again, this discussion mostly references display of moving images - i.e. watching video content. On a desktop monitor, technologies like local dimming are mostly not used - simply because issues like 'bleeding' around light to dark transitions are MUCH more noticeable on a static image than an image updating, say, 60 times a second, with the content in motion.

To date, we see mostly edge lit designs for desktop LCD monitors, and particularly those that need IPS Panels - i.e. colour accurate panels. Which means - until e.g. we start seeing colour accurate desktop OLED models appearing - that other approaches to improving black performance (vs. local dimming) are required in this context.

At this size, 4K is not really a lot of pixels per inch, by modern standards.  At 140 PPI, this noticeably below the 200 PPI standard for so-called 'retina' displays - although that figure originates more from phones, which you of course hold much closer to your eyes.  For monitors, generally about 150PPI gives a similar effect due to the greater screen↔eye distance.

You simply don't quite get the same feeling of page-like sharpness you get from smaller 4K units.  4K on a 27" screen I find to be ideal (albeit technically this is still only ~165 PPI.  With those, you're at the point of sharpness that you just don't feel any practical need for more.  Text and even very small UI elements are rendered very sharply and are easy for the eye to parse.  But that same 4K resolution stretched over a 32 inch monitor is just not quite the same.

In a perfect world, you'd have 6 or 8K on a display this size.  Those days will come, of course, but we're simply not there yet, and of course it's not just about the monitor - more and more computing power is needed to drive more and more pixels.

For now, at this size, 4K is as good as it gets on colour accurate displays, so the question is kind of moot.  Just note that if you're after maximum sharpness, you might prefer the 27" models (like the BenQ PD2725U) - although you won't get the bonus visual performance of the IPS black panel.

(On the other hand, if you're somehow still worried about issues with 4K - those days are really long behind us now).