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ViewSonic has added to its 4K monitor range since we reviewed the VX2880ml, which is part of ViewSonic's entertainment series, in September 2014. The new VP2780-4K, reviewed here, is aimed at professional users, while another 4K newcomer, the VG2860mhl-4K, fleshes out ViewSonic's business series.
The VP2780-4K is a 27-inch,16:9 aspect ratio IPS display, with a White LED backlight and a 5ms (GtG, or grey-to-grey) response time. Its native resolution is 3,840 by 2,160 pixels (at up to 60Hz refresh), and it provides 14-bit processing and 10-bit-per-channel colour depth, offering DisplayPort, HDMI and MHL (Mobile High-Definition Link) video inputs. Each VP2780 is manually calibrated during manufacture to a colour consistency across the display of less than or equal to 2 Delta E. ViewSonic offers a zero pixel defect warranty for the life of the product, along with its standard four-year overall product warranty. At the time of writing, the ViewSonic VP2780-4K costs around £730 (inc. VAT; £608.33 ex. VAT).
A multi-picture feature allow you to view up to four video sources in up to 1080p resolution and backlight flicker is eliminated by the use of DC brightness control rather than PWM (Pulse Width Modulation).
For easy height adjustment, horizontal and vertical rotation and tilt, the VP2780-4K is supplied with a fairly slender, spring-counterbalanced pedestal, bolted to the 4-point VESA standard mounting on the back of the display. A removable three-way foot connects to the base of the pedestal with a rotating bayonet coupling, locked in place by a single thumbscrew. Although it's stable enough during normal use, there is a degree of flex in the pedestal that may become noticeable when you're adjusting the display.
All connections, apart from two side-access USB 3.0 ports, are mounted on a recessed back panel approximately 10cm above the bottom left-hand corner (viewed from the front of the display). Individual connectors are identified by a grey legend printed on the black shell of the display, which is unfortunately faint and hard to read. There is an upstream USB 3.0 input and two downstream USB 3.0 outputs, DisplayPort (DP) 1.2 and Mini-DisplayPort connectors, three HDMI 2.0 sockets, two of which are MHL 2.0 compliant, and a stereo headphone jack. A co-axial jack connects to the outboard 19V DC power supply, which in turn connects to mains power through a 3-pin IEC320-C6 cable.
ViewSonic sticks with its standard left-to-right layout of five touch areas for the user controls, located on the lower right corner of the display surround. These are labelled with a 1, 2, down arrow, up arrow and a power symbol. A multi-colour status LED, showing blue or orange for on or off, is integrated into a 'mitre' line across the corner of the display frame. On our review sample, even in low levels of ambient light, the LED itself was very dim. An option in the user menu allows the LED to be turned off, but not increased in brightness.
Repeatedly touching the '1' toggles the main on-screen menu on and off, while tapping the '2' (with the on-screen menu off) directly opens the monitor input select menu. The main on-screen menu offers the following choices: Contrast/Brightness, Input Select, Audio Adjust, Colour Adjust, Information, Manual Image Adjust, Setup Menu and Memory Recall. There are no built-in speakers and amplifiers on this monitor.
Tapping the down arrow brings up the Blue light filter adjustment, while tapping the up arrow opens a user settings menu offering factory default and three user-defined choices. When the on-screen menu is selected from the '1' the arrows become vertical menu navigation controls and the '2' becomes the item-select control. Within menus, '1' is used to exit and only the '1' control exhibits a toggling behaviour.
Colour settings and the Blue light filter
The 'Blue light filter' shortcut, accessed via the down arrow, provides a single slider for adjusting the blue channel to set the display to 'warmer' tone or a lower colour temperature. Strictly speaking, this isn't a filter, but an alternate colour balance control intended to minimise eye damage.
The Colour Adjust submenu has five presets; sRGB, EBU (European Broadcast Union), Bluish, Cool, Native and Warm, plus the User Colour sub-submenu which allows individual settings for red, green and blue. The sRGB choice looks obviously a smaller gamut and lower brightness than the other settings, Bluish sets a relatively high colour temperature and the other four settings produce progressively warmer tones / lower colour temperatures. The factory default 'native' colour setting is quite obviously a 'warm', or reduced-blue, colour setting.
Whatever Blue light filter setting is made this is always overridden by selections from the main Colour Adjust menu and User Colour settings are always remembered.
Manual image adjustments
The Manual Image Adjust submenu provides control over some unusual settings among its selections: Sharpness, Dynamic contrast, Response time, Aspect ratio, Overscan, Eco mode, Gamma, Multi-picture, View mode and Blue light filter.
Take gamma, for example: adjustments to image gamma are normally the province of profile correction performed by a colour management system. It's something of a dirty secret that the inherent transfer curve of LCDs tends to an S shape and is quite different from that of the older CRT technology. Inherent to the latter is an input-signal-to-brightness relationship that's a power law curve, the gamma figure being the exponent of that curve. For CRTs gamma equals around 2.2. Windows adopted a display-centric gamma of 2.2 as its standard, while for long time Apple operating systems used a print-centric gamma of 1.8. Gamma for displays -- CRT or LCD -- was, and remains, usually fixed. The ViewSonic VP2780 offers a choice of five gamma correction settings: 1.8, 2.0, 2.2, 2.4 and 2.6.
Until recently, 10-bit-colour-capable monitors with 14-bit LUTs (Look Up Tables) were limited to the specialist high-end market. A display with 10-bit colour (per channel, or 30-bit colour) may seem like a good thing for the colour professional but, at least for now, 10-bit colour it isn't 'user transparent'. It's not just a question of plugging in a 10-bit capable monitor -- 10-bit colour must also be supported and enabled on your graphics card, in your graphics drivers, and in your operating system and applications. GPU manufacturer Nvidia provides instructions on its website for enabling 30-bit colour on Windows and on Linux for its 30-bit capable products. The current version (2.8) of GIMP, the open-source GNU Image Manipulation Program, still only supports 24-bit colour, but greater bit depths may be available in version 2.9.
Adobe products, such as Photoshop CS6 and above, support 30-bit, but it's an option that must be turned on. Microsoft has supported 30-bit colour since Windows 7, although apparently basic Windows functionality, such as font smoothing, can be compromised by switching to 30-bit colour. Whether or not Yosemite, the current version of Mac OS X, supports anything beyond 24-bit colour is unclear.
Plugged into a 24-bit system, a 30-bit capable monitor is no better than a 24-bit monitor. Moving to 4K and 10-bit colour is not just a question of a new monitor, but most probably of upgrading your entire system and software. Some colour professionals say that using a 24-bit system with a 16-bit or even a 14-bit 3D LUT and a good colour management system delivers just as good results as a 30-bit colour system, and with fewer issues.
You get three signal cables with the VP2780-4K: a standard DisplayPort cable, a mini-to-standard DP cable and a Mini-DP cable. Three-pin UK and two-pin continental CEE 7/16 Europlug mains cables are supplied, which plug into the external power supply via a three-pin 'clover leaf' connector. The power brick, which measures 13.4cm by 6cm by 3cm, automatically adapts to mains input between 100V and 240V AC and supplies 19V DC to the monitor via a captive cable with a coaxial connector.
Basic setup instructions are provided on two paper sheets, while the multi-language user guide comes on a CD. Also supplied is the pedestal stand with its three-way foot.
Resolution alone does not guarantee a better image; refresh rate is important too, which for 4K is mainly limited by the bandwidth of the video interface. Over HDMI 2.0 and DisplayPort 1.2 the maximum refresh rate is limited to 60Hz, which is better than the 30Hz of HDMI 1.4 but arguably still slow enough that image quality -- particularly on moving images -- is affected. The most recent standard, DisplayPort 1.3, supports 4K at up to 120Hz refresh and may appear in products in 2016.
The VP2780-4K's image quality is very good and the careful factory calibration means that it may be possible to use this monitor for colour-critical tasks without further colour management. Other manufacturers supply 27-inch 4K monitors, of course, but it's hard to find a comparable display with the professional colour specifications of ViewSonic's VP2780-4K at this price point.