It’s been two years and, among the nitpicky tech-enthusiasts, LG Display is still often seen as producers of subpar mobile OLED panels after the poor reception of their displays in the Pixel 2 XL and LG V30 ThinQ. In late 2018, the LG V40 ThinQ came to market, which showcased the second generation of LG’s mobile OLED panels. Surprisingly, it demonstrated genuine improvement and established LG Display (LGD) as a proper mobile OLED competitor, as evaluated in our in-depth review of the V40 ThinQ’s display. Formerly identified with some of the most offensively blue viewing angles, LGD’s continuous research and development in mobile OLED resulted in new panels that now have the best viewing angles on a smartphone display, and with peak brightness and color gamuts matching that of Samsung Display Co.’s. With the rumors of the LG G-series adopting OLED technology formerly exclusive to the V-series, I was naturally very eager to see if there were further improvements made compared to the LG V40 ThinQ’s display, which was one of my favorite displays of 2018. Thus, we turn to the new LG G8 ThinQ to find out.
Good
|
Bad
|
|
xda DISPLAY GRADE B |
LG G8 ThinQ Performance Summary
The P-OLED panel on the LG G8 ThinQ has one of the most densely pixel-packed displays on the market at 564 pixels per inch, containing 3120×1440 (19.5:9) PenTile Diamond pixels over its 14.2 square-inch (6.1-inch diagonal) screen. By default, the screen is set to render at 2340×1080, which is approximately 422 pixels per inch, but it appears slightly less dense due to resampling since the render resolution does not divide wholly into the native resolution.
The panel has excellent uniformity in low brightness and continues LGD’s trend of having some the best viewing angles among mobile OLEDs, although the brightness drop-off on the G8 ThinQ panel seems a little higher than the one found on the V40 ThinQ. Black clipping or black crush is also handled well and should not be an apparent issue.
The LG G8 ThinQ introduces a new display feature called “True view,” which works like Apple’s “True Tone” by shifting the color temperature of the display towards the color temperature of the ambient lighting. This is a feature that I really enjoy on iPhones that I wish more Android OEMs would adopt. In my usage of the G8, the feature seems to work the best in the Auto color profile.
The display gets competitively bright, and on average may reach up to 855 nits (50% APL), just shy of the Galaxy S10’s 893 nits. Content with a lot more white space, such as Gmail, lowers the overall display brightness, and at these whiter content pixel levels the G8 ThinQ display only peaks up to 570 nits, compared to 643 nits for the iPhone X and 723 nits for the Galaxy S10. While measuring for the absolute highest white level that the G8 ThinQ display is capable of emitting, it managed to output an astounding 1124 nits at a tiny 1% APL, on par with the 1130 nits emitted by the Galaxy S10 at the same APL.
The native gamut of the LG G8 ThinQ display is very wide, making it capable of reproducing very vibrant colors. It can fully cover the P3 gamut as well as covering most of the greens in the Adobe RGB gamut. The LG G8 ThinQ’s default Auto color profile stretches colors out for a very vibrant and punchy look, with hot reds that steer slightly towards yellow, and very vibrant greens that appear slightly cooler. The profile also has a very cool color temperature to it.
The tone response of the display (also called the gamma), which controls screen contrast, is very high on the G8 and scales aggressively. The higher the display brightness and content pixel level, the higher the gamma and the resulting screen contrast, which is jarringly noticeable at max brightness. This display characteristic also happens to increase color saturation with display brightness. On one hand, it is actually desirable to increase color saturation at higher ambient lighting to offset the color gamut reduction from the ambient lighting. However, to offset the black level lift from ambient light sources, display gamma actually needs to be lowered to lighten the shadows and colors under bright lighting, but instead, the G8 ThinQ increases gamma with display brightness, which makes the display less legible under bright light.
The standard reference color profiles, which are meant to be color-accurate, are troublesome because of the dynamic gamma mentioned above. All the profiles, as a result, are oversaturated and will increase in saturation the higher the display brightness. The sRGB color space is the most important color space to target accurately, since almost all content is described in it, and it is the color space contexed by default for all colors on the internet. The G8 ThinQ’s Web profile targets the sRGB color space, and, throughout the display’s brightness range, has a resulting ΔE of 3.2, which is among the poorest color accuracies measured for a flagship’s standard reference profile in a long time. What’s interesting is that, together with the dynamic gamma, the total color accuracy of the display decreases linearly as brightness increases; the display is actually the most accurate at its dimmest, which is also when color accuracy is the least important since human eye cone response to colors is poor at these levels.
Methodology ▼
Color Profiles
The default profile on the LG G8 ThinQ is the Auto profile, calibrated with brighter, orange-ish reds, and very vibrant greens that have a cool tint to them. The white point is cold at 7274 K and remains consistent throughout the brightness range. In this profile, you are able to alter the relative Red-Green-Blue intensities of the screen, and adjust the color temperature to range from magenta-ish to more cyan-ish — all the temperature slider positions actually have similar correlated color temperatures, just different color balances. The Expert profile is available to further modify the relative saturation, hue, and sharpness of the display.
The Sports profile is the same as Auto, just with relatively higher blues throughout, and measuring a colder 7615 K white point.
The Game profile is similar to Auto, slightly colder at 7443 K and with its red primary reaching out to P3 red.
The Web profile is a non-color managed standard reference profile that targets the sRGB color space with a D65 white point and is the most important reference profile to be calibrated correctly. Because the display’s dynamic gamma system cannot be disabled, color accuracy is problematic on the G8 ThinQ because it oversaturates chromaticities the higher the set white level. Furthermore, Android’s automatic color management system is not present for this profile, which aids in properly displaying content described in other color spaces that isn’t sRGB. The Cinema and Photos profiles are the two other standard reference profiles, and they target the P3 and Adobe RGB color spaces, respectively. With a proper color management system, those two color profiles would not be necessary.
Brightness
Our display brightness comparison charts compare the maximum display brightness of the LG G8 ThinQ relative to other displays that we have measured. The labels on the horizontal axis on the bottom of the chart represent the multipliers for the difference in perceived brightness relative to the LG G8 ThinQ display, which is fixed at “1×”. The magnitude of the displays’ brightnesses, measured in candelas per square meter, or nits, are logarithmically scaled according to Steven’s Power Law using the modality exponent for the perceived brightness of a point source, scaled proportionally to the brightness of the LG G8 ThinQ display. This is done because the human eye has a logarithmic response to perceived brightness. Other charts that present brightness values on a linear scale do not properly represent the difference in perceived brightness of the displays.
When measuring the display performance of an OLED panel, it is important to understand how its technology differs from traditional LCD panels. LCDs require a backlight to pass light through color filters that block wavelengths of light to produce the colors that we see. An OLED panel is capable of having each of its individual subpixels emit their own light. This means that the OLED panel must share a certain amount of power to every lit pixel from its maximum allotment. Thus, the more subpixels that need to be lit up, the more that the panel’s power needs to be divided over the lit subpixels, and the less power that each subpixel receives.
The APL (average pixel level) of an image is the average proportion of each pixels’ individual RGB components across the entire image. As an example, a completely red, green, or blue image has an APL of 33%, since each image consists of completely lighting up only one of the three subpixels. The complete color mixtures cyan (green and blue), magenta (red and blue), or yellow (red and green) have an APL of 67%, and a full-white image that completely lights up all three subpixels has an APL of 100%. Furthermore, an image that is half black and half white has an APL of 50%. Finally, for OLED panels, the higher the total on-screen content APL, the lower the relative brightness of each of the lit pixels. LCD panels do not exhibit this characteristic (barring local dimming), and because of it, they tend to be much brighter at higher APLs than OLED panels.
The peak display brightness is slightly improved from the V40 ThinQ, but a clear regression from the super bright MLCD+ display on the G7 ThinQ. At an average pixel level of 50%, which is a good midpoint to generalize the brightness of an OLED display, the G8 ThinQ reaches up to 855 nits, which is visually just as bright at the 893 nits on the Galaxy S10. The LG G8 ThinQ display does suffer from high dynamic brightness falloff, however, and drops down to peaking at 570 nits at 100% APL, slightly below the latest iPhones. At a tiny 1% APL, the LG G8 ThinQ is able to reach up to 1124 nits, which is just as bright as the Galaxy S10.
The LG G8 ThinQ does not get as dim as the competition, or even as dim as the V40 ThinQ, measuring 2.7 nits at minimum brightness, compared to sub-2 nits for most other flagships and 2.3 nits for the V40 ThinQ.
Contrast & Gamma
The gamma of a display determines the overall image contrast and lightness of the colors on a screen. The industry standard gamma that is to be used on most displays follows a power function of 2.20. Higher display gamma powers will result in higher image contrast and darker color mixtures, which the film industry is progressing towards, but smartphones are viewed in many different lighting conditions where higher gamma powers are not appropriate. Our gamma plot below is a log-log representation of a color’s lightness as seen on the LG G8 ThinQ display versus its associated input drive level. Measured points that are higher than the 2.20 line mean the color tone appears brighter than standard, while lower than the 2.20 line means the color tone appears darker than standard. The axes are scaled logarithmically since the human eye has a logarithmic response to perceived brightness.
Most modern flagship smartphone displays now come with calibrated color profiles that are chromatically accurate. However, due to OLED’s property of lowering the average lightness of the colors on the screen with increasing content APL, the main difference in the total color accuracy of modern flagship OLED displays is now in the resulting gamma of the display. The gamma makes up the achromatic (grayscale component) image, or the structure of the image, which humans are more sensitive in perceiving. Therefore, it is very important that the resulting gamma of a display matches with that of the content’s, which typically follows the industry standard 2.20 power function.
Tone response, usually known as gamma, is the most important display aspect for total color accuracy. The human visual system is more sensitive to the contrast of an image than its colors, and a display’s gamma determines the contrast of the screen. On average, the picture on the LG G8 ThinQ display appears with higher contrast than usual, but what’s problematic is that the display gamma varies wildly depending on the display’s total emission, a combination of the display brightness and the content pixel level: at an APL of 50%, the measured display gamma ranges from 2.23 at minimum brightness, all the way up to a toasty 2.67 at maximum brightness. Throughout the display’s brightness range the gamma averages out to 2.42, which has fairly more contrast than standard, though darker content with lower APLs will appear fairly accurate.
Note that a varying gamma is not inherently a bad thing; ideally, a display should have a gamma of 2.4 in 0 lux ambient light (pitch black), lowering to 2.2 at about 200 lux, and reducing even further the higher the ambient lighting, to achieve the same visual contrast appearance on the display at different lighting. However, the LG G8 ThinQ display gamma is changing with respect to display brightness instead of ambient lighting, and the display gamma is increasing instead of decreasing. This is likely partially due to OLED luminance regression, but the delta is among the highest I’ve seen and measured since the Samsung Galaxy Note 8.
Moreover, the individual tristimulus (RGB) values are affected directly by the varying gamma, increasing the decoding gamma of the chromaticities, which pushes/“compresses” colors closer towards 100% gamut saturation, and increases the working gamut. This is not a usual result of miscalibration, because decoding gammas of chromaticities are not altered by relative channel adjustments. This is either intentional to increase display saturation at higher ambient lighting or an oversight in the display driver. The gamut and decoding gamma are most normal at the lowest display brightness, which suggests that gamma characteristic is an intentional function of display brightness since panels are never primarily (or at least they shouldn’t be) calibrated at their minimum brightness.
What’s also interesting is that the LG G8 ThinQ seems to have some sort of dynamic contrast control, possibly left in as a software solution to the LG G-series’ previous LCD displays, that briefly adjust the lightness of all the colors on the screen depending on what seems to be the average relative luminance of the screen. Initially, I thought this was set in place to counteract the OLED brightness regression characteristic, but the display still has a medium-high dynamic brightness response to content APL (15%) and a high display gamma.
Color Temperature & Drive Balance
The color temperature of a white light source describes how “warm” or “cold” the light appears. Color typically needs at least two points to be described, while the correlated color temperature is a one-dimensional descriptor that leaves out essential chromaticity information for simplicity.
The sRGB color space targets a white point with a D65 (6504 K) color temperature. Targeting a white point with D65 color temperature is essential in color accuracy since the white point affects the appearance of every color mixture. Note that, however, a white point with a correlated color temperature that is close to 6504 K may not necessarily appear accurate! There are many color mixtures that can have the same correlated color temperature (called iso-CCT lines) — some that don’t even appear white. Because of this, the color temperature should not be used as a metric for white point color accuracy. Instead, we use it as a tool to represent the rough appearance of the white point of a display and how it shifts over its brightness and grayscale. Regardless of the target color temperature of a display, ideally its correlated color temperature of white should remain consistent at all drive levels, which would appear as a straight line in our chart below.
The drive balance charts show how the intensities of the individual red, green, and blue LEDs vary with display brightness, overlayed with the display’s correlated color temperature of white, and they reveal the “tightness” of the color calibration of the display. The charts show much more color information than the one-dimensional color temperature chart. Ideally, the red green and blue LEDs should remain as consistent as possible throughout the display’s brightness range.
The standard reference profiles — Web, Cinema, and Photos — appropriately all share the same white point calibration and drive balance. In these profiles, the green LED remains pretty balanced and straight throughout the display’s brightness range, and the red LED is mostly straight, except for a noticeable dip as the display nears 100% brightness, and an increasing bias below 1% signal level. The blue LED is the problematic drive, dominating most of the display’s lower brightness range and dramatically going under near 100% signal level. As a result, very dark grays are shifted magenta, while mid-grays and low-brightness whites appear blue-shifted. Whites at about the 100-200 nits range appear the most balanced (albeit slightly red-shifted), while higher white levels begin to shift green as the luminously-efficient green LED begins to take over to primarily increase the display’s brightness.
The Auto profile is the most consistently calibrated profile, most likely since the profile is the panel’s default factory calibration. The correlated color temperature of the profile is very consistent throughout the entire brightness range, only really compromised by an imbalance nearing 100% brightness that, while keeping the correlated color temperature similar, shifts the white point more towards greenish-cyan, and still shifting magenta for very dark grays, but to a less-noticeable extent than the standard profiles.
Color Accuracy
Our color accuracy plots provide readers with a rough assessment of the color performance and calibration trends of a display. Shown below is the base for the color accuracy targets, plotted on the CIE 1976 chromaticity scale, with the circles representing the target colors.
Base Color Accuracy Plots chart
In the color accuracy plots below, the white dots represent the position of the LG G8 ThinQ’s measured colors. The associated trailing color represents the severity of the color error. Green trails signify that the measured color difference is very small and that the color appears accurate on the display, while yellow trails indicate noticeable color differences, with higher severity at orange and red trails.
The Web profile targets the sRGB color space, so it is the most important profile to assess for color accuracy. In the Contrast and Tone Response section, I mentioned how the tristimulus values and corresponding chromaticities were directly affected by the increasing display gamma when display brightness increases. Because of this, the color accuracy of the profile varies significantly with display brightness, ranging from an accurate ΔE of 1.6 at minimum brightness to a profoundly inaccurate ΔE of 4.6 at maximum brightness, averaging ΔE = 3.2 ± 1.7 throughout the display’s perceptual brightness range. Color-accurate work using the sRGB color space is typically done on displays with a white level between 80–200 nits, and at these brightness levels, together with its high display gamma, the LG G8 ThinQ cannot be considered color-accurate and is unfit for color-sensitive work.
The other standard profiles are not that much better, although they are slightly lower due to lower chromaticity expansion since they are wider gamut. The Cinema profile, which targets the P3 color space, has a ΔE of 2.9 ± 1.7, while the Photos profile, which targets the Adobe RGB color space, has a ΔE of 2.6 ± 1.6. Neither break the ΔE = 2.3-threshold to be considered “accurate”, and both having exceedingly high standard deviations because of the dynamic gamut.
LG G8 ThinQ Display Overview
Closing Remarks on the LG G8 ThinQ
Compared to the LG V40 ThinQ and the LG G7 ThinQ, the LG G8 ThinQ might not seem like a huge upgrade. To some, it might even be a worse display. The LG G8 ThinQ does not get as bright as the G7 ThinQ, and the G8 ThinQ does not provide a profile as color-accurate as on the V40 ThinQ. Nevertheless, most consumers will probably stick to the default Auto color profile and enjoy the vibrant colors that the profile provides. The panel gets comparably bright as its competitors, with very vibrant and punchy colors, and an option to adjust the white point color temperature or to adapt it to your surroundings. The inconsistent tone response remains the primary issue, being purely detrimental and providing a less-predictable picture with no advantages to its property. The “Auto profile”–“Auto brightness”–“True view” experience is actually quite pleasant, with no other adverse shortcomings, like an excessive black crush or display non-uniformity. Actually, I lied: for the very keen-eyed, there is a smidgeon of display grain I was able to notice on my G8 ThinQ, which I had to really look for and can’t notice at typical viewing distances. This was a slight shame since I wasn’t able to detect any at all with the V40 ThinQ display. The omission of no real color-accurate profile may be a dealbreaker to specific people like content creators (at which LG seems to have been aiming at with their manual video controls and “Hi-fi” audio), or those who just like knowing that what they’re seeing is accurate, but if you’re able to live without nerd-caliber color-accuracy, the LG G8 ThinQ display is just absolutely fine.
Buy the LG G8 ThinQ (U.S.)Buy the LG G8 ThinQ (Canada)
The post LG G8 ThinQ Display Review — LG’s Focus Lies Elsewhere appeared first on xda-developers.
0 comments:
Post a Comment