Philips 328P6VUBREB

Interlace pattern artifacts

On some monitors, particularly but not exclusively those with high refresh rates, interlace patterns can be seen during certain transitions. We refer to these as ‘interlace pattern artifacts’ but some users refer to them as ‘inversion artifacts’ and others as ‘scan lines’. They may appear as an interference pattern or mesh or interlaced lines which break up a given shade into a darker and lighter version of what is intended. They often catch the eye due to their dynamic nature, on models where they manifest themselves in this way. Alternatively, static interlace patterns may be seen with some shades appearing as faint horizontal bands of a slightly lighter and slightly darker version of the intended shade. We did not observe either artifact type on this monitor.

Responsiveness

Input lag

A small utility called SMTT 2.0 was used alongside a sensitive camera to analyse the latency of the 328P6VUBREB, with over 30 repeat readings taken to help maximise accuracy. Using this method, we calculated 28.85ms (a little under 1.75 frames at 60Hz) of input lag. This was no different in the ‘Game’ preset, which as usual applies different image settings rather than making any changes to signal processing. Note that we don’t have the means to accurately measure the input lag in an HDR environment, but the HDR setting selected in the OSD didn’t seem to affect things under SDR usage. Note that the input lag measured here is influenced by both the element you ‘see’ (pixel responsiveness) and the element you ‘feel’ (signal delay). It indicates quite a high signal delay for a monitor, which some users will find bothersome.

Perceived blur (pursuit photography)

In our article on responsiveness, we explore key concepts surrounding monitor responsiveness. An important concept explored in the article is ‘perceived blur’, which is contributed to by both the pixel responsiveness of the monitor but also eye movement as you track motion on the screen. This second factor usually dominates on modern monitors, although both are important. We also introduce a photography method called ‘pursuit photography’, which uses a moving rather than static camera to capture snapshots of motion on a monitor in a way that reflects both of these key elements of perceived blur rather than only reflecting pixel responses.

The images below are pursuit photographs taken using the UFO Motion Test for ghosting, with the test running at 960 pixels per second. This is a good practical speed for capturing such photographs and highlights both elements of perceived blur nicely. The UFOs move across the screen from left to right at a frame rate matching the refresh rate of the display. All background shade levels (dark, medium and light) were used with the monitor set to all its ‘SmartResponse’ pixel overdrive settings; ‘Off’, ‘Fast’, ‘Faster’ and ‘Fastest’. The final column includes a reference shot, a Dell S2417DG set to its optimal pixel overdrive setting for 60Hz. This model uses a fast TN panel without significant pixel response time limitations and shows how things look where pixel responsiveness isn’t really a limiting factor.



The UFO appears blurred and unfocused, without distinctive detailing. This reflects a moderate amount of perceived blur due to eye (camera) movement. In addition to this, there are varying amounts of trailing behind the UFO. This trailing is caused by weaknesses in pixel responsiveness. With ‘SmartResponse = Off’, there is quite a bold and extended trailing for the back background (top row). It’s also quite prominent for the medium background (middle row) and fainter for the light background (bottom row). There is a small amount of overshoot (inverse ghosting) visible for the light background, a slight bright ‘halo trail’. With ‘SmartResponse = Fast’ the trailing is cut down a bit overall. For the dark background the trailing is shorter. It’s less extensive in all cases, but certainly still there for the dark background in particular. There is also slightly stronger (but still mild) overshoot for the light background and a bit introduced for the medium background. The trailing behind the UFO cockpit there has a slightly dirty appearance due to this, but nothing that stands out in an obvious way during normal observation. The ‘Faster’ setting cuts down on the conventional trailing further, introducing more noticeable overshoot. The ‘Fastest setting’ strengthens the overshoot further and gives obvious bright trailing. In practice we found the ‘Fast’ setting gave the best balance between pixel responsive times and overshoot. The ‘Faster’ setting introduced some very obvious overshoot for some transitions not explored above, we found this too noticeable in practice.

Note that we will not be including a section on overclocking, as the monitor skipped frames when set much above 60Hz at its native resolution or indeed lower resolutions such as Full HD.

Responsiveness in games and movies

On Battlefield 1 (BF1) there was a fair amount of perceived blur, caused mainly by eye movement and linked to the 60Hz refresh rate. There were also some weaknesses linked to the pixel response behaviour, which all VA models have to some degree. Most pixel transitions were performed fast enough to either give an optimal performance for the 60Hz refresh rate, with some slight weaknesses being quite widespread where medium-dark shades were presented. There was a slight ‘mask’ of additional blur due to ‘powdery trailing’ in places, which is faint and short-lived enough that it didn’t prove too eye-catching or distracting. It just slightly increased perceived blur, but the refresh rate (and frame rate) and perceived blur due to eye movement were far more significant contributors. There were some more pronounced weaknesses involving dark shades – so-called ‘high-contrast transitions’. Here the trailing took on a somewhat ‘smeary’ appearance, sometimes just like a ‘heavier’ (bolder) version of the ‘powdery trailing’ observed elsewhere. But most noticeable with examples of what we call ‘break-up trailing’. This is whereby some shades contained within the dark areas (like purples, browns and reds) that aren’t readily visible when the scene is static leach out as if you’re wetting water-soluble ink on a page. This ‘smeary’ trailing was not particularly bad for the panel type, however. It was certainly there, but not as bold or extensive as on some models we’ve tested – including the Philips BDM4037UW. There was also a small amount of overshoot in places, with some semi-transparent trailing that was sometimes slightly lighter or darker than the object or background colour. But nothing that really caught the eye. The section of the video review below illustrates some of these trailing examples and discusses the responsiveness of the monitor more broadly.

These observations were echoed on Shadow of the Tomb Raider. For the most part there were no real stand-out weaknesses. Perceived blur was largely as you’d expect from a 60Hz LCD with decent pixel overdrive, with a slight extra mask from the light ‘powdery trailing’ in places. Darker shades are common on this title, however. So the examples of ‘smeary trailing’ observed on BF1 were present here and generally more widespread. There was nothing extreme, though, and we weren’t distracted from actually playing the game due to the weaknesses in pixel responsiveness. Sensitivity to such things varies, however. We didn’t observe any eye-catching overshoot, either, only some isolated examples where we were specifically looking out for it. We also observed the responsiveness using a range of movie titles and other video content. This was mainly lower frame rate content (24 – 30fps), for example on Netflix. The overall visual fluidity and indeed the demands on pixel response speed are limited by the relatively low frame rate, so there weren’t really any obvious weaknesses from the monitor’s pixel responses. For higher frame rate content (e.g. 60fps) the weaknesses observed when gaming applied. But, again, we didn’t find them extreme for a VA panel at all. The pixel overdrive was quite well-balanced overall and we’d rate this as one of the more capable VA models in terms of pixel responsiveness.

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HDR (High Dynamic Range)

HDR (High Dynamic Range) on a monitor requires the simultaneous display of very deep dark shades and very bright light shades. Furthermore, it is necessary for the monitor to be able to display a large gamut of colours with good precision, from weakly saturated pastel shades to strongly saturated shades as well as those in between. The ideal HDR monitor would have very precise control over its illumination, ideally per-pixel (OLED and suchlike). This would allow very intricate mixtures of bright and dark to be displayed with exceptional contrast. Failing that, an FALD (Full Array Local Dimming) backlight is desirable whereby the backlight is split into several hundred or more dimming zones. This doesn’t give you the same control and precision as per-pixel illumination (which is essentially millions of dimming zones) but a large number of dimming zones can still deliver a strong HDR contrast experience. For colour reproduction, it is desirable for a monitor to offer a gamut of >90% DCI-P3 (a Digital Cinema Initiatives standard colour space). This is the near-term target, with the ultimate goal of complete coverage of an even wider colour gamut; Rec. 2020. Finally, it is desirable for the display to offer (at least) 10-bits per channel for colour output, giving it exceptional precision when mapping shades for HDR content.

For most games and other full screen applications supporting HDR, the Philips 328P6VUBREB will automatically switch into its HDR mode when the appropriate setting is selected in the game or application. Provided, that is, that you have selected either ‘Normal’ of ‘VESA HDR 600’ for ‘HDR’ in the ‘Picture’ section of the OSD. It is specifically HDR10 that is supported on this model and indeed all current HDR-capable monitors. As of the Windows 10 ‘Creator’s update’, HDR support was integrated into the OS with a feature initially called ‘HDR and advanced colour’. This is now referred to as ‘HDR and WCG’ (meaning Wide Colour Gamut). A minority of game titles that support HDR will only run in HDR if this setting is active in Windows and if you wish to view HDR movies on a compatible web browser, for example, you’ll need to activate this setting as well. If you’re not actively viewing HDR content on the desktop then having this enabled can make things appear flooded and washed out, so it’s only supposed to be activated when it’s specifically needed. The setting can be found in ‘Display settings’ (right click the desktop) as shown below.

The Philips 328P6VUBREB is VESA DisplayHDR 600 certified. This level of certification, broadly speaking, means that a monitor offers a ‘mid-range’ HDR solution – enough to make a significant difference to the visual experience, hopefully in a positive way. A particularly important aspect of the VESA DisplayHDR 600 certification is that it necessitates local dimming on the backlight. The monitor is able to dim some sections of the screen whilst brightening others, improving contrast ratio. Although Philips don’t officially specify the exact backlight arrangement used, our testing confirms that an edge-lit arrangement is used with 8 LED clusters running down both side edges of the screen. Combined with light guides, this essentially splits the screen into 16 zones with a degree of independent luminance control for each. The monitor doesn’t offer any local dimming support under SDR, only under HDR. You can see from the figures earlier on in the review (in the contrast section) that the local dimming capability did work, to a degree, to somewhat enhance the contrast of the screen. It also allowed it to reach a higher peak luminance under the full ‘VESA HDR 600’ OSD setting, a rather bright 670 cd/m². The diagram below gives a rough indication of the dimming zone locations on the screen. It is by no means designed to be completely accurate, it’s simply to help illustrate the solution described above.

We observed various game titles (and a range of movie content) using HDR on the monitor. We found that some implementations were certainly better than others, but the monitor itself largely dictated HDR performance on a broader level. We will therefore be focusing on a few titles which put HDR to good use; Battlefield 1 (BF1) and Shadow of the Tomb Raider on our PC test system. Our observations here are similar to what you’d observe on game console titles which support HDR as well as whilst watching HDR movie content. Just as in the title we test, such content is written with the HDR10 pipeline in mind. The testing performed here focuses on and is limited by the capabilities of the monitor itself rather than the system. Firstly, we’d like to give the ‘Normal’ setting a brief mention. Brief because we found it delivered an experience that was simply not ‘dynamic’ enough to encompass a true HDR experience. The maximum luminance was simply too limited for bright elements to have the sort of eye-catching look you’d expect from HDR. The ‘VESA HDR 600’ setting, on the other hand, gave bright elements in the game a really eye-catching ‘pop’ that goes far beyond what you observe with HDR disabled. On Shadow of the Tomb Raider, for example, glints of light reflecting off water and shiny objects stood out very nicely. The raised peak luminance coupled with local dimming support also gave daylight areas a brighter and more natural look. Because local dimming was employed this isn’t the same as simply applying a universally high luminance, which floods the image. There were some very impressive elements where brighter and darker shades intertwined, for example light streaming in through an opening in the forest canopy. The image below illustrates the elements we’ve just discussed, but in no way reflects what they look like first hand on the monitor. It’s just to set the scene.

When it came to scenes involving predominantly darker content, there were some good and not so good elements to highlight. Firstly the good. The HDR10 pipeline calls for 10-bit colour reproduction and more careful and precise tone mapping, which on monitors like this are coordinated with localised luminance changes from the local dimming solution. This means that more subtle details for both dark and light elements are far more distinct than under SDR. They aren’t brought out in a way that is akin to simply raising gamma (and flooding the image, bringing about extra detail whilst killing depth and atmosphere) but in a far more pleasing and natural way. The enhanced processing of HDR also forms much smoother gradients, which is noticeable in both darker and lighter areas. The distinct rays of light and misty appearance to the opening in the forest canopy (not captured at all in the image) had a very natural appearance, with smooth, gradual and precise shade changes. Now for the not so good. The dark areas weren’t as deep and atmospheric as we’d like to see. This was most noticeable where there was a single or limited number of light sources illuminating an otherwise very dark area. On Tomb Raider this was common in caves, tombs and dark passageways. On BF1 an example would be a lantern or small patches of moonlight illuminating dark building interiors. Because the native contrast of the screen was decent, these areas didn’t look completely flooded and still had reasonable depth. But they certainly didn’t have an inkiness to them – that is reflected by the black point readings in the contrast section. We also observed a sort of spotlighting effect, because at least some of the LED clusters were having to lighten quite a lot to make sure the bright elements of the scene were nice and bright. At the expense of the darker mass surrounding it. Towards the corners of the screen you could essentially see backlight bleed, with the LED clusters themselves partially visible – you can see a similar effect under SDR if you raise the luminance up far beyond the levels used in our ‘Test Settings’. A more effective local dimming solution, with a greater number of dimming zones, would be required to alleviate these issues. The section of the video review below runs through these strengths and weaknesses with HDR on the monitor.

Another important aspect of the HDR experience is colour reproduction. The near-term target for HDR is strong DCI-P3 coverage. The VESA DisplayHDR 600 standard requires a minimum of 90% DCI-P3 – the Philips has a specified 98% DCI-P3 coverage, so a big tick there. With content creators targeting the DCI-P3 gamut, it means monitors which cover this well can output an excellent array of shades with appropriate saturation. This contrasts with simply displaying content designed with sRGB in mind (a game under SDR, for example) on a colour gamut this wide as it curtails the oversaturation. Skin tones are more appropriately muted (no more overly tanned Lara Croft), earthy browns appear rich but not due to an excessive red hue and green vegetation appears lush, deep and appropriately varied with lots of more muted shades. Rather than overly bright in places and somewhat less natural than intended. But stronger saturation can be injected where it is warranted, including some of those lush forest greens but also beautiful orange and yellow glowing fires, brightly painted houses and little environmental elements. On Tomb Raider, for example, there were some flowers and fruit which had more of a vibrant ‘pop’ to them using HDR than under SDR. The colour gamut of the monitor is shown below, as compared to sRGB and Adobe RGB earlier in the review. You can see the extra coverage beyond sRGB and can imagine the effect that has on the images when game developers can accurately map such a broad range of shades.

Colour gamut 'Test Settings'