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HP Z27x Dreamcolor Professional Display Review
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1. HP Z27x DreamColor Professional Display Review

When you go sit down to watch a Hollywood blockbuster like Transformers: Age of Extinction or Edge of Tomorrow, most of what you see on the screen originated on a computer. CGI effects have come a long way in the past few years thanks to ever-faster computing platforms and improvements in display technology.

To properly master today’s digital films, artists need a color-accurate monitor that can easily switch between the major color, grayscale, and gamma standards currently in use. That means support not only for sRGB and Adobe RGB, but DCI (Digital Cinema Initiative) and Rec.2020 as well.

We’ve reviewed many screens that cover Adobe RGB. But only one other, NEC’s PA272W, can do DCI. Today, we’re checking out HP’s entry into the professional monitor market: its Z27x. This display not only covers the aforementioned three gamuts, it also supports a subset of Rec.2020, the new proposed standard for Ultra HD.

Panel Type & Backlight
AH-IPS
GB-r-LED, edge array
Screen Size & Aspect Ratio
27-inch / 16:9
Max Resolution & Refresh Rate
2560x1440 @ 60 Hz
Native Color Depth & Gamut
10-bit / Adobe RGB+
Response Time (GTG)
7 ms
Brightness
250 cd/m2
Speakers
-
Video Inputs
2 x DisplayPort, 1 x HDMI
Audio
3.5 mm, Coax digital
USB
v3.0: 1 x up, 4 x down
v2.0: 2 x down
Ethernet
1
Panel Dimensions
W x H x D w/base
25.5 x 16.6-21 x 9.5 in
648 x 443-536 x 241 mm
Panel Thickness
2.6 in / 65 mm
Bezel Width
.8 in / 21 mm
Weight
19.4 lbs / 8.8 kg
Warranty
Three years

The technology in HP's Z27x is fairly unique among computer monitors. Its core panel is made by LG, like so many others. But this is not an off-the-shelf part. Modifications are made to the grid polarizer and backlight to improve upon both color accuracy and off-axis viewing quality.

As with other wide-gamut displays, the backlight is GB-r-LED. Green and blue LEDs shine through a red phosphor coating, allowing for a larger color gamut and greater accuracy from primary colors that have consistent spectral peaks. One drawback is that it’s difficult to achieve a perfect blue primary. Other GB-r-LED monitors we’ve measured do show either under- or over-saturation there. HP modifies the Z27x’s backlight with a custom blue LED to correct the issue. To help combat fatigue when artists have to pull an all-nighter editing images of Optimus Prime, constant-current (rather than pulse-width modulation) is used to control panel intensity. Add this display to the list of flicker-free products.

The other major change is in the grid polarizer. Every LCD panel, TN or IPS, focuses the light emitted by each pixel through a polarizing layer. Without it, you’d see a blurry image due to light spread, similar to how printing on certain types of paper can de-focus the picture coming from an inkjet printer. The dots enlarge and reduce clarity.

The grid polarizer is why LCD’s image quality degrades when viewed off-center. IPS is superior in this regard because its polarizer is much thinner than the one used in TN-based panels. HP tweaks its implementation further to improve off-axis quality in the vertical plane. Most displays we’ve photographed look fine from 45 degrees to the side, but not as good when viewed from 45 degrees above. The Z27x retains more detail and light output from that angle than other IPS panels.

There are many more features we’ll talk about as you read on. The Z27x is a direct result of feedback gained from artists at some of the top visual effects houses, and HP literally engineered the Z27x to meet their specific requests. Our own hands-on experience tells us this is a unique product with few, if any, equals, especially at its price point. Let’s take a look.

2. Packaging, Physical Layout And Accessories

The Z27x comes packed sturdily in a large double-corrugate carton. It’s so deep you might think two monitors are inside. The bundle covers every possible connection option. In addition to HDMI, there are two DisplayPort cables (one has a mini-plug) and USB 3.0 Standard A-to-B. An IEC power cord feeds current to the internal power supply. You also get a complete inspection report that covers dead pixels, screen uniformity, and several other quality control parameters. It’s a professional product for sure, and HP checks each one carefully before it goes out the door.

The base and upright are already assembled, so all you have to do is snap it onto the back of the panel.

Product 360

From the front, the Z27x is all business. Its anti-glare layer is of light density, so users in brightly-lit workspaces may want to consider purchasing the optional hood for critical work. Image clarity is among the best we’ve seen. Bezel buttons are located in the lower-right, and are mechanical rather than touch-sensitive. They can be lit either white or red, and feel high-end in operation. By default, they fade to black after the OSD leaves the screen.

The Z27x can be positioned easily with a full set of ergonomic adjustments. The height range is 4.75 inches and you can tilt the panel -5 to 20 degrees. Swivel covers 45 degrees in either direction and there is a portrait mode that automatically rotates the image.

The monitor isn’t terribly slim, but that’s to ensure proper ventilation of the internals (which are substantial). The USB ports are version 3.0-compliant, and there are two more on the input panel. Just behind the ports is a little pull-out card that shows the serial number and other pertinent information, saving you from look behind the panel when calling tech support.

To use the 100 mm VESA mount, simply unsnap the upright. HP includes an adapter plate that allows tool-free installation to a variety of arms and brackets. The four holes next to the upright span 40 mm and facilitate attachment of additional accessories.

The input panel is all-digital, save the analog audio output that can drive either speakers or headphones. You’ll also notice the S/PDIF digital audio output, which is something we haven’t seen outside of an HDTV. Again, video inputs include one HDMI and two DisplayPort 1.2. There's a USB 3.0 upstream port and two downstream connections as well. The USB 2.0 ports are intended for a calibration instrument. When a supported one is detected, the internal calibration routine opens automatically. Finally, you get an Ethernet jack for control and administration purposes. It works both ways, allowing you to poll the Z27x for information like screen hours or calibration status. Settings and firmware updates can be sent to connected displays as well.

Signal Handling

The Z27x has some unique capabilities when it comes to signal handling. Since it is primarily designed as a mastering monitor for broadcast content, it accepts all resolutions currently in use by the film and television industry. This includes resolutions larger than its native 2560x1440.

Most Hollywood movies are mastered first in the Digital Cinema Initiative realm, meaning a resolution of at least 2048x1080 spanning as high as 4096x2160. The Z27x can accept both of these and everything in between. And it can crop the screen to 1.85:1, 1.89:1, and 2.39:1 aspect ratios. As if that weren’t enough, it can handle 24p, 48p, and 60p frame rates (though at 4096x2160, it’s limited to 24p). And all of this can be done over HDMI if your graphics card is compatible.

The way it handles 4K resolutions is intuitive. You can choose to scale the image so all of it fits on the screen. Or, you can show a specific quadrant of the image (or its center zone). Finally, you can scroll around the image using on-screen navigation arrows. In this mode, it’s mapped pixel-for-pixel, so you’re seeing the content with no scaling or processing.

3. OSD Setup And Calibration Of The HP Z27x

The Z27x can’t be calibrated using the OSD, but there are many options to configure. Most features are included to address specific user requests. We’ll cover the calibration procedures below. First, though, let’s check out the monitor’s other features.

OSD Tour

Pressing any key brings up a quick menu. Once the Z27x is set up, you rarely need to venture past this point.

Selecting Luminance brings up a slider that tracks pretty closely to the actual brightness value. We found it to be off by about 5 cd/m2.

There are two pages of signal and monitor information available. Most visual effects artists work in multiple colorspaces, so it’s important to know how the display is set. If you color correct a project using the wrong settings, a lot of time can be wasted.

Note that in addition to the serial number, you also get a firmware version. This really helps when tracking support issues across a large group of displays.

The second screen has detailed signal info, including scan rates and color formats.

Here’s the main menu tree. You can change the color space without going in this far if you want, but if you make changes from the main OSD, you get a few extra options.

There are seven color modes corresponding to broadcast industry standards, plus a Native mode. That’s where you’ll find extra light output if you need it, as the other modes are limited to 250 cd/m2. You can also back up to a previous calibration or reset to the factory one. If you select Color Space Information, this screen pops up:

This is a quick and easy way to see all image parameters in one place. You can review the color coordinates in either xy or u’v’ format, and you get the white point and gamma specs. When calibrating the Z27x, any specs can be assigned to any color mode. For example, if you wanted a 2.4 gamma in Rec.709 instead of 2.2, you’d only need to specify that when you calibrate.

Here are some options you won’t find on many computer monitors. Video levels are different from PC levels, and the Z27x lets you specify them on the fly. Let’s say you’re mastering a Blu-ray transfer. You’d have to view the signal with video levels to set the black and white thresholds correctly.

Overscan imitates the typical five-percent zoom-in many HDTVs do when not set to a pixel-mapped aspect ratio. If you’re composing an image, it helps to know what content will be cut off and this option shows that.

Showing only the blue channel is a way to easily see compression and encoding errors when mastering content.

Selecting Advanced accesses three more features.

Overdrive is found on most computer monitors today. It simply attempts to reduce motion blur by bumping up the pixel clock.

Deinterlacers are found on all progressive-scan displays. Most computer monitors include a rudimentary video processor to accomplish the task, but the Z27x boasts a more advanced solution. To correctly process film-based video, you need a proper implementation of 3:2 pull-down, which HP provides. If you’re working on film-to-video transfer, this feature is invaluable. You can turn both that and Cadence Detection on and off to check for content encoding errors.

PIP options are pretty typical, though the Z27x adds the ability to use video levels and/or overscan for one source only. That makes it easy to compare images to one another.

Digital Cinema Options are grayed out unless a signal of 4096x2160 or 2048x1080 is input. Those resolutions are known as DCI containers. Once you do this, you can crop the image to a 1.85:1 or 2.39:1 aspect ratio, which corresponds to the two most common film formats in use today.

The Management sub-menu has many options that help both users and administrators manage the display. Most of them have an enable/disable switch. DisplayPort compatibility can be set to either version 1.1 or 1.2.

The most important option available is Manage Internal Processor. Enabling this turns on the Z27x’s internal calibration engine. It also allows firmware updates and remote management.

Remote Management Services allow administrators to control multiple Z27x displays via IP, provided you connect them to your network through the Ethernet jack. HP provides a downloadable API that has a large list of management features. When active, administrators can check the calibration status, display hours, and many other statistics simply by polling the displays remotely.

The OSD can be positioned anywhere on-screen. We moved it to the lower-right, leaving the center of the screen free for test patterns. The timeout can be up to 30 seconds.

The bezel buttons can be programmed for different monitor functions, saving you a trip to the OSD. It’s handy when you want to quickly switch aspect ratios or engage overscan, for example.

When working in a dark office, the bezel lighting can make a significant impact on image perception. By default, the buttons fade to black when the OSD disappears. But if you prefer, they can be always white or red. You can also have them switch automatically to red when the luminance is set below 70 cd/m2.

Lastly, the Z27x has a portrait mode that automatically flips the image. This doesn’t extend to the OSD though, necessitating a manual flip in the settings.

Calibration

Calibration options for the Z27x are somewhat different than the norm. There is no way to adjust image parameters using the OSD, aside from color mode selection and luminance level. The factory calibration is pretty accurate according to our tests, but HP recommends re-adjusting every 1000 hours. To that end, there is an internal engine that can automatically calibrate using a supported meter.

The least-expensive solution is HP’s DreamColor Calibrator. It’s an i1Display-based colorimeter made by X-Rite and costs an additional $250. If you want to use a more precise instrument, the Z27x supports five different Photo Research spectroradiometers, along with the Minolta CA-210 and Klein K10-A units. They plug right into one of the USB 2.0 ports and can calibrate without any connection to a computer.

We obtained the DreamColor solution from HP and calibrated four different color space modes. When you plug in, a menu pops up where you can enter gamma, white point, luminance, and color gamut choices. These can be saved to any of six memories. Then you place the calibrator on the screen and the Z27x does the rest. It took us about one minute per color mode, while a spectro can take up to 40 minutes.

As you’ll see in our tests, the DreamColor instrument didn’t really improve upon the factory setup. We feel that, to realize the Z27x’s full potential, you’d need to use an i1Pro at minimum. Unfortunately, the only way to use that particular instrument is with the latest version of CalMAN. It has the appropriate software hooks to calibrate the monitor and write to its internal look-up table.

4. Results: Brightness And Contrast

To read about our monitor tests in-depth, please read Display Testing Explained: How We Test Monitors and TVs. Brightness and Contrast testing is covered on page two.

Today’s comparison group consists of wide-gamut screens only. We have Dell’s two 4K models, the UP3214Q and UP2414Q; NEC’s excellent PA272W; Viewsonic’s VP2772; and BenQ’s PG2401PT. All of them are professional-grade products that come with a factory-documented calibration.

Uncalibrated: Maximum Backlight Level

HP rates the Z27x at 250 cd/m2 in its calibrated modes and we got readings around 260 cd/m2 in all of them. To reach the panel’s maximum output of 313.2169 cd/m2, you have to use the Native mode, though. Its color gamut is close to Adobe RGB anyway, so you could use the monitor that way if you needed it in a high ambient light situation like a location shoot. For the display’s intended use, however, 260 cd/m2 is more than enough brightness.

The maximum black level is quite respectable at .2948 cd/m2. While accuracy is the principle goal of this product, HP hasn’t forgotten the importance of a wide dynamic range and high contrast.

A measurement of 1062.3 to 1 is over our standard of 1000 to 1, making HP the top performer. It doesn’t get much better in the IPS computer monitor world. One hope we have for future improvement is VA technology, which more than doubled the above results when we tested BenQ's BL3200PT. Combining that level of contrast with the Z27x’s accuracy would make for a killer display.

Uncalibrated: Minimum Backlight Level

Dropping the Z27x’s backlight to its minimum setting yielded 54.8765 cd/m2 output. That's a great light level for working in the almost total darkness of a CGI artist’s editing station.

The top four screens all have correspondingly lower minimum white levels, so these results are no surprise. The PA272W bottoms out at a dim 19.8634 cd/m2; its minimum black level would be tough to work with.

Ultimately, the greatest impact on image quality comes from contrast and the HP maintains its lead in our group of elite screens. Our hands-on use of the Z27x confirms that all kinds of content reap the benefit of its wide dynamic range. There is plenty of depth and dimension in whatever you’re looking at.

After Calibration to 200 cd/m2

Here’s what black levels and contrast look like after calibration with the max output set at 200 cd/m2:

We calibrated the Z27x using HP’s DreamColor solution, which is a modified i1Display colorimeter. The adjustments it made to the factory configuration were minimal, so the numbers are almost unchanged. The black level is still impressive, though.

NEC just edges out the Z27x, but the difference is small enough that you probably wouldn’t see it in a side-by-side comparison. Given the luminance results, we can say that HP boasts contrast performance better than almost all of its competitors.

ANSI Contrast Ratio

The Z27x regains its top spot. When the ANSI number is this close to the on/off value, we know the grid polarizer is of very high quality. HP’s custom part appears to improve contrast as well as off-axis image integrity.

5. Results: Grayscale Tracking And Gamma Response

Our grayscale and gamma tests are described in detail here.

We’re going to show the grayscale, gamma, and color results for the four most-used color modes: sRGB, Adobe RGB, DCI, and Rec.2020. They are the color standards professionals would likely employ in their work.

Our before and after results were similar, so we’re showing just the post-calibration charts. We used an i1Display-based instrument, which is not the best tool for measuring color in our experience. We believe if the Z27x were adjusted with an i1Pro or high-end spectroradiometer, the results would be even better.

For sRGB mode, we used the standard white point of D65 or 6500 Kelvins. The measurements run a tiny bit warm, though the error is invisible at all brightness levels. The average Delta E value is 1.85.

Switching to Adobe RGB, also at D65, results in a little extra blue as brightness levels rise. At 90 percent you can just see a tiny error. The average error is 2.21 Delta E.

The DCI white point is typically set at D54. It injects a little extra green to compensate for the different spectral properties of a commercial projector’s xenon bulb. The Z27x runs too cool, and shows errors at 50-percent brightness and above. The average error is 5.63 Delta E. If you plan to work in the DCI colorspace, we recommend using an i1Pro or better to calibrate.

Since the Z27x only shows a subset of the Rec.2020 gamut, grayscale suffers from a slight lack of green. To our eyes, it looked too blue. Again, the error is visible from 50 percent on up, and has an average value of 3.52 Delta E.

Here is our comparison group:

We’re comparing the Z27x’s best mode, which is sRGB. Running the internal calibration routine with a DreamColor i1Display produced almost no change in the grayscale result.

A .01 rise in average Delta E is essentially nothing in this test. To extract the Z27x’s maximum potential, a spectrophotometer or spectroradiometer should be used to calibrate, rather than the tri-stimulus instrument we employed. While these are decent results, we believe they could be better.

Gamma Response

The Z27x doesn’t support gamma BT.1886 in its current firmware. By the time you read this, we're told that omission will have been rectified. All the gamma presets are based on the power function. For sRGB and Adobe RGB, that means a value of 2.2.

The resulting trace is pretty good except for a slight dip (too bright) at the 10-percent level. The luminance error is .9356 cd/m2, which is barely visible. Otherwise, tracking is nice and tight at the 2.2 mark.

The Adobe RGB trace is within a whisker of perfection. The target is the same as for sRGB (2.2). The dip at 90 percent represents a less-than 1.8 cd/m2 error, well below the threshold of visibility.

DCI specifies a gamma of 2.6 and the Z27x matches it almost exactly. The dip at 90 percent is just 2 cd/m2 of extra brightness.

Rec.2020 is still a proposed standard and for now, it calls for a gamma value of 2.4 using the power function. The HP screen shows the same dip at 90 percent as the other color modes. But this time, it’s greater at over 9 cd/m2. Since BT.1886 is being phased in with Rec.709 content, it seems likely that standard will make its way to Rec.2020 UHD displays eventually.

Here is our comparison group again. The Z27x’s results represent the sRGB color mode.

A result of .09 is extremely tight tracking. Other than the slight error at 90 percent, gamma is perfect in the sRGB, Adobe RGB, and DCI modes.

We calculate gamma deviation by simply expressing the difference from 2.2 as a percentage.

If it weren’t for the dip at 90 percent, the deviation would likely be zero. We believe the Z27x can achieve this if calibrated with the right instruments.

6. Results: Color Gamut Accuracy

For details on our color gamut testing and volume calculations, please click here.

As on the previous page, we’re showing the results from sRGB, Adobe RGB, DCI, and Rec.2020 modes after calibration with the DreamColor Calibration System. Since it’s not the best meter for adjusting color, we don’t feel our charts represent the full potential of the Z27x. Even so, the monitor still performs extremely well.

This is a result we feel few would find fault with. The white point is a tiny bit red, but not visibly so. Blue is slightly under-saturated as you move to the edge of the gamut, but its luminance is tweaked higher to compensate. The overall errors are completely invisible. For all intents and purposes, this is perfect color.

Near-perfect color performance is also found from the Adobe RGB mode. Blue is more on-target than before. The only thing we can see wrong is that magenta is a little off in hue.

The DCI color gamut doesn’t have quite as much green as Adobe RGB, but that primary (as well as red) is closer to the edge of the visible spectrum. The NEC PA272 we tested lost a little ground on that side of the triangle, which the Z27x hits its target quite well. The visible errors are only in the hue of cyan. All other colors and saturation levels are under the three Delta E level. Users mastering for the DCI spec are unlikely to find a more accurate mastering monitor.

The Rec.2020 gamut is large, as you can see, and the Z27x is only able to render a subset of it. The mode is included at user request. Right now, though, there are no displays available at any price that can actually show it all. In fact, engineers I’ve spoken to aren’t sure if it can be achieved with today's technology.

Now we return to the comparison group. The Z27x result is from its sRGB mode.

Considering the limitations of calibrating with a tri-stimulus meter, an average error of 1.29 Delta E is fantastic. It’s the same figure in Adobe RGB. The DCI average error is 2.39 and in Rec.2020 it’s 3.19 Delta E. No matter what mode you use, the color accuracy is top-shelf.

Gamut Volume: Adobe RGB 1998 And sRGB

We’re pretty sure the Z27x is capable of hitting 100 percent for both sRGB and Adobe RGB if calibrated with a spectrometer. We came up slightly short in the DCI mode with 88 percent of the gamut rendered. In Rec.2020, HP claims 68-percent coverage, but we measured 70 percent.

7. Results: Viewing Angles, Uniformity, Pixel Response And Input Lag

To learn how we measure screen uniformity, please click here.

Viewing Angles

Our photos look similar to other GB-r-LED monitors we’ve seen with one important difference. Even though the same red color shift exists in the vertical plane, shadow detail is superior. If you check out photos of the NEC PA272W, you’ll see that the darkest steps are more washed out than they are here. HP’s custom grid polarizer definitely has a visible benefit.

Screen Uniformity: Luminance

HP specifically chose not to use any uniformity compensation because of its negative effect on contrast and, to a lesser degree, color. Obviously it’s not missed on our review sample. A black field number below 10 percent means there are no visible hotspots on the screen. Combined with the Z27x’s low black level, it looks perfect to our eyes.

Here’s the white field measurement:

While this isn't the best result we’ve recorded, it is still perfect to the naked eye. The NEC and BenQ screens are represented with their uniformity compensation turned on. HP sees no need for the feature, and we agree with it.

Screen Uniformity: Color

The Z27x’s error of 3.54 Delta E is mainly caused by a barely perceptible green shift in the upper-right corner of the screen. It’s impossible to see in actual content and another sample might measure differently. Out of all the tests in our benchmark suite, it’s the only result we could call less-than-stellar.

Pixel Response And Input Lag

Please click here to read up on our pixel response and input lag testing procedures.

The Z27x is an AH-IPS screen and its draw time of 25 milliseconds confirms this. There are no blur-reduction options available, though you do get an overdrive setting. It helps reduce motion blur, but doesn’t reduce the measured response time. With typical video content, there are no issues. Regardless, we don’t expect many hardcore gamers to add a monitor like this to their rig.

Here are the lag results:

Input lag is also about average for a 60 Hz IPS display. Most people could game on the Z27x without issue. But if you’re looking for maximum frame rates and super-fast response, there are better alternatives out there.

8. HP Z27x DreamColor Display, Accuracy And Flexibility

If you’ve made it this far, you can see that the Z27x is no ordinary computer monitor. In fact, it’s so much more that it may have just defined its own category. Before now, filmmakers either had to adapt to an inexpensive wide-gamut display or pony up five figures for a mastering monitor from Sony, Panasonic, or JVC. HP makes it much easier for VFX and post-production facilities to equip their artists with an accurate display capable of handling whatever content they need to work on.

In the world of broadcast and film production, there are many displays in use that you’d never find sold alongside monitors or HDTVs. I’m talking about mastering displays that can easily top $20,000 for a 24-inch FHD screen. CGI and post-production artists require absolute color accuracy, easy and quick calibration, and the ability to work in a variety of signal formats and aspect ratios.

Many professional-level monitors can do some of these things. But ultimately, products like ViewSonic's VP2772 or Asus' PA279Q leave out critical capabilities like DCI color support or an internal calibration engine. HP really bridges the gap by creating a monitor that has the functions and quality of a $20,000+ mastering display for only $1500.

This is the first product we’ve tested that even attempts to support the Rec.2020 color gamut, and only the second that covers DCI. Those gamuts are a must if you're going to properly color-correct a Hollywood feature film. There are plenty of screens to choose from if all you need is Adobe RGB. That’s more in the realm of photography and you don’t have to spend $1500 to get there.

The Z27x is also unique in its resolution support. It’s the first display we’ve seen that can accept a resolution greater than its native pixel count. With more and more content moving to 4K, studios need displays that can show them exactly what they’ve filmed and what the viewer will ultimately see. There are pro-level 4K displays available, but even something like Dell's UP3214Q will set you back $2500. And it won’t do everything this HP can do.

Of particular interest to us is the internal calibration engine. The ability to simply plug in a meter, answer a few questions on-screen, and walk away while the monitor calibrates itself is huge. Users working in color-critical environments can’t afford even the slightest mistake, which means re-calibration is a regular part of the workflow. Tweaking the OSD while working in an app like CalMAN achieves the result but can take a lot of time. Now you can walk away while the monitor does its thing.

At the beginning we told you that HP created the Z27x in response to requests from users at some of the top VFX houses. If you put this display on your desk, there's a good chance you'll be looking at the same monitor used by the talented artists at DreamWorks and Pixar. Color accuracy and easy calibration are very valuable features, whether you’re working on the latest Michael Bay feature or simply color-correcting product photos for a website.

The Z27x combines tremendous accuracy with a large and unique feature set that caters to professionals in all areas of computer-generated imagery. That it can achieve this for $1500 puts it in a class by itself. For that reason, we’re giving it the Tom’s Hardware Elite award.