vendredi 12 mars 2021

OPPO Find X3 Pro Display Review: Solid Quality All Around

Piggybacking off of last year’s feats of “industry-leading color accuracy”, OPPO continues to set its sights even further. With its new full-path color management system, the OPPO Find X3 Pro furthers OPPO’s aim to improve image fidelity from camera to gallery. The Find X3 Pro also adds a new LTPO adaptive refresh rate panel, which will help save extra battery life for the high-resolution, high refresh rate panel.

In his review of the OPPO Find X3 Pro, XDA’s Ben Sin described the screen as “nearly flawless” and as “immersive and brilliant as the panels [he’s] seen in the [Samsung Galaxy] S21 Ultra or Xiaomi Mi 11.” Featuring a large 6.7-inch 3216 x 1440 resolution AMOLED panel, the OPPO Find X3 Pro packs premium display tech and commands an equally premium price. In this review, I’ll be taking a quantitative approach to analyzing the display of OPPO’s latest flagship.

OPPO Find X3 Pro Forums

The OPPO Find X3 Pro unit used for this review was loaned to us by OPPO. However, OPPO did not provide any input or compensation for this review.

Display Review Highlights

  • Excellent peak brightness
  • Excellent sRGB and P3 color accuracy in calibrated color modes
  • Exceptional grayscale precision in Gentle profile
  • Consistent contrast and tone mapping throughout profiles
  • Adaptive refresh rate solution yields no color shift
  • Gets super dim with automatic “Reduce contrast” feature
  • Slight color tint in shadows in the Vivid profile
  • Warm default white point in calibrated color profiles
  • Loss of MEMC and DC Dimming

Software display features

The OPPO Find X3 Pro comes with what OPPO calls its O1 Ultra Vision Engine, which consists of a “Video image sharpener” and a “Video color enhancer”. The features are self-explanatory from their titles. I did not personally test their efficacy in this review, but something to note is that they both claim to increase battery usage and cannot both be enabled at the same time.

The display is also capable of automatic white balance via the Nature tone display feature, which works similarly to Apple’s True Tone feature. Unfortunately, this feature cannot work in tandem with the screen color temperature adjustment, so if you prefer a cooler or warmer white point than what the automatic white balance sets it to, you’re out of luck.

OPPO collaborated with a company called Pixelworks, which specializes in video and image processing, for these features. We have a separate article that covers the capabilities of Pixelworks’ other software and processors. Pixelworks is also responsible for the factory display color calibration of the Find X3 Pro.

Compared to last year’s flagship, the OPPO Find X3 pro is actually missing some features. Namely, it’s missing the video motion interpolation feature (MEMC) and the DC dimming feature. The reason for the lack of MEMC this year is due to the omission of the Pixelworks X5 chip, which the Find X2 Pro used last year to implement some of its display features.

Moving on, another display feature in the OPPO Find X3 Pro is the automatic Reduce contrast option within the Dark mode settings. This feature further dims the display brightness when the system brightness is low and when in dark mode, bringing down the white level from 2.1 nits to 0.9 nits. It’s incredibly useful when using the phone near bedtime, and it’s become my favorite display feature of the phone.

Color vision enhancement is an accessibility feature that corrects colors for those that have color hue deficiencies. It allows you to first take a color vision test to check if you do indeed have a deficiency, and besides the feature, the test itself is pretty fun to take.

Color vision test

Lastly, the full-path color management system is OPPO’s solution to accurately rendering both sRGB and Display P3 content within the Vivid profile. This system is paired with the OPPO Find X3 Pro’s capability of capturing photos in the wider Display P3 color space. It seems to overhaul Android’s own color management system, and from my findings, it’s kind of just the opposite of Android’s solution. Instead of letting Android switch between color spaces for sRGB and Display P3 content, OPPO’s solution keeps the display in the Display P3 color space and lets the Gallery app decode images to sRGB or Display P3.

Methodology for gathering data

To obtain quantitative color data from the OPPO Find X3 Pro, I stage device-specific input test patterns and measure the display’s resulting emission using an X-Rite i1Display Pro metered by an X-Rite i1Pro 2 spectrophotometer in its high-resolution 3.3nm mode. The test patterns and device settings I use are corrected for various display characteristics and potential software implementations that may alter my desired measurements. My measurements are typically done with display-related options disabled unless mentioned otherwise.

I use constant power patterns (sometimes called equal energy patterns), correlating to an average pixel level of about 42%, to measure the transfer function and grayscale precision. It’s important to measure emissive displays not only with constant average pixel level but also with constant power patterns since their output is dependent on the average display luminance. Additionally, a constant average pixel level does not inherently mean constant power; the patterns I use satisfy both. I use a higher average pixel level closer to 50% to capture a midpoint between both the lower pixel levels and the many apps and webpages with white backgrounds that are higher in pixel level.

I use the latest color difference metric ΔETP (ITU-R BT.2124), which is an overall better measure for color differences than ΔE00 that is used in my earlier reviews and is still currently being used in many other sites’ display reviews. Those that are still using ΔE00 for color error reporting are encouraged to use ΔEITP.

ΔEITP normally considers luminance (intensity) error in its computation, since luminance is a necessary component to completely describe color. However, since the human visual system interprets chromaticity and luminance separately, I hold our test patterns at a constant luminance and do not include the luminance (I/intensity) error in our ΔEITP values. Furthermore, it is helpful to separate the two errors when assessing a display’s performance because, just like with our visual system, they pertain to different issues with the display. This way, we can more thoroughly analyze and understand the performance of a display.

Our color targets are based on the ITP color space, which is more perceptually-uniform than the CIE 1976 UCS with much better hue-linearity. Our targets are spaced out roughly even throughout the ITP color space at a reference 100 cd/m2 white level, and colors at 100%, 75%, 50%, and 25% saturation. Colors are measured at 73% stimulus, which corresponds to about 50% magnitude in luminance assuming a gamma power of 2.20.

Contrast, grayscale, and color accuracy are tested throughout the display’s brightness range. The brightness increments are spaced evenly between the maximum and minimum display brightness in PQ-space. Charts and graphs are also plotted in PQ-space (if applicable) for proper representation of the actual perception of brightness.

ΔETP values are roughly 3× the magnitude of ΔE00 values for the same color difference. A measured color error ΔETP of 1.0 denotes the smallest value for a just-noticeable-difference for the measured color, while the metric assumes the most critically-adapted state for the observer so as not to under-predict color errors. A color error ΔETP less than 3.0 is an acceptable level of accuracy for a reference display (suggested from ITU-R BT.2124 Annex 4.2), and a ΔETP value greater than 8.0 can be noticeable at a glance, which I’ve tested empirically.

HDR test patterns are tested against ITU-R BT.2100 using the Perceptual Quantizer (ST 2084). HDR sRGB and P3 patterns are spaced out evenly with sRGB/P3 primaries, an HDR reference white level of 203 cd/m2 (ITU-R BT.2408), and a PQ signal level of 58% for all its patterns. All HDR patterns are tested at an HDR-average 20% APL with constant power test patterns.

Color profiles

OPPO Find X3 Pro display modes Color gamut for the OPPO Find X3 Pro

The OPPO Find X3 Pro comes with four distinct color profiles, each of which changes the color characteristics of the screen.

The Vivid profile is the phone’s default color profile, and it’s characterized by increased color saturation, a bluish-white point, and slightly higher contrast than standard. More specifically, the profile stretches colors out to the Display P3 color space (except for in the stock Gallery app), with a white point measuring about 7000 K and a target gamma power of about 2.30 (compared to the standard of 2.20). OPPO foregoes Android’s native color management system for its own “full-path color management system”, which I’ve found to only be functional within the stock OPPO Gallery app. As per the “full-path color management system” in this profile, photos viewed within the stock Gallery app will be rendered in the sRGB color space by default for color-accurate photo viewing, while P3-tagged photos (such as those taken by the OPPO Find X3 Pro’s camera) will be displayed in the profile’s native P3 color space.

The Gentle profile is a factory-calibrated color profile that targets the sRGB color space, which is the default color space of the Internet and the original color space of most content. The profile targets a gamma power of 2.20 (not the original sRGB transfer function), and the white point of the profile is meant to target the industry-standard D65 illuminant, which corresponds to a color temperature of 6504 K. However, I’ve measured a value closer to about 6200 K for the Gentle profile, which is slightly warmer. At the time of publication, this profile currently does not support Android’s color management, but OPPO tells us that they plan to add color management as part of a system update at the end of March.

The Cinematic profile is another factory-calibrated color profile similar to the Gentle profile, but it instead targets the Display P3 color space. This profile is not accurate just because it is calibrated to a color space; it will still stretch out sRGB colors out to P3, and it is only accurate when viewing properly-encoded P3 content. It is the most niche out of all the profiles, and it should only be used when color accuracy is the highest priority for viewing actual P3 content — or if you just like the look of the color mode.

The Brilliant profile is the most saturated color profile available to the OPPO Find X3 Pro. The profile shares a similarly-bluish white point as the Vivid profile, as well as targeting Display P3 for its red and green color primaries. Moreover, it has further-increased saturation in blues, and the profile can get slightly brighter by increasing the lightness of colors depending on the average pixel level (APL) of the content.

All profiles also provide the option of adjusting the color temperature of the white point, but only when the Nature tone display feature isn’t active since it automatically adjusts the white point to the ambient lighting. Ideally, the two options should work together, with the color temperature slider acting as a bias for the automatic white balance feature. However, there are no devices that I know of with this capability.

Brightness

Peak luminance vs content APL

The peak brightness of the OPPO Find X3 Pro is excellent, typically reaching about 750-800 nits in its high brightness mode. Like most other Androids, this brightness can only be reached when the phone detects a lot of light from its ambient light sensor, such as when it’s brought outside on a sunny day.

Since the OPPO Find X3 Pro uses an OLED panel, the brightness of the pixels change depending on the average pixel level (APL) of the content that is currently being displayed. For fullscreen white, which is where OLEDs consume the most power, the OPPO Find X3 Pro is able to output about 740 nits. When the phone is in its default Vivid profile, the phone moderately varies its brightness of white with APL, and at a median-50% APL, the Vivid profile can output up to 800 nits, which is a touch lighter. The Gentle and Cinematic profiles control their brightness variance, and they have almost no change in luminance with content APL.

These brightness values are about identical to last year’s Find X2 Pro, and while they’re not as bright as Samsung’s latest flagships, these are still respectable figures in 2021.

On the low end, the Find X3 Pro’s dimmest brightness setting yields a white level of about 2.1 nits, which isn’t quite as dim as some other OLEDs that can get down to about 1.7 or 1.8 nits. However, the OPPO Find X3 Pro has a setting called “Reduce contrast in low light conditions” in its Dark mode display settings, and this allows the white level to go down to about 0.9 nits, which is excellent for nighttime viewing. This feature is especially useful since it’ll only activate during dark mode and when the display brightness is low enough.

The 'reduce contrast in low light conditions' setting is incredibly useful when using the phone near bedtime, and it's become my favorite display feature of the phone.

Contrast and Tone Mapping

Measured at 40% APL (~27% Target ADL)

The default Vivid profile is measured to be decently accurate to the standard 2.20 gamma power, although it does render shadows and midtones just slightly darker throughout its luminance range (except for at minimum brightness). This results in the appearance of slightly higher contrast for the Vivid profile, which complements its vibrant nature. Most other phones also have increased contrast in their respective Vivid profile, but only because they allow the profile to vary its luminance with APL in that profile, resulting in increased contrast but only at higher brightness settings. What makes the OPPO Find X3 Pro somewhat different is that it seems consistent with its increased contrast, even at lower brightness settings. This makes it seem that the profile’s increased contrast is targeted instead of just being a consequence of an OLED characteristic, which is good. In general, a consistency in relative perceived contrast throughout a display’s luminance range is desirable, and it shows proficient calibration control and thoughtfulness.

Measured at 40% APL (~27% Target ADL)

For the phone’s calibrated color modes (Gentle and Cinematic), OPPO demonstrates excellent tonal control. The profiles track the standard 2.20 gamma power nice and tightly throughout its entire luminance range, resulting in both accurate and consistent display contrast, which not many displays are capable of.

At minimum brightness, both profiles have a slight lift in shadows and midtones so that dark details don’t appear completely crushed. This is good attention to detail, but I personally find that a little more lift is needed for a more comfortable viewing experience in low light. The OPPO Find X3 Pro is capable of rendering 1/255 gray, even at minimum brightness, but unless your eyes are dark-adapted, dark tones can still appear crushed.

Not many displays are capable of both accurate and consistent display contrast, but the OPPO Find X3 Pro demonstrates excellent tonal control.

When the Find X3 Pro is out in the sunlight at max brightness, targeting a lower gamma power instead of the profile’s nominal target would help improve the legibility of the display in those brighter conditions. When viewing photos in high brightness mode, there is indeed some dynamic tone mapping present that boosts shadows and midtones, but it only seems to activate within OPPO’s stock Gallery app. Last year’s Find X2 Pro did this for the entire Gentle profile, so not seeing it in the Find X3 Pro was a bit of a surprise. The legibility of the Vivid profile on the new phone is an improvement, however, since its gamma was actually too high at high brightness on last year’s model.

White Balance and Grayscale Color Precision

Grayscale plots for Vivid profile, 120 Hz

In the phone’s default color profile, a slight green tint can be observed for dark gray color tones at lower brightness levels (below ~25% system brightness). It’s not drastically noticeable, but those that are sensitive to color tints may be bothered by it, especially within dark mode interfaces. Besides that, the white point does appear to be consistent throughout different brightness settings for this profile. However, the average color temperature of the white point (~7000 K) does slightly differ from the average color temperature of the entire grayscale (~6700 K).

Grayscale plots for Gentle & Cinematic profile, 120 Hz

Conversely, the Gentle and Cinematic color profiles are calibrated with outstanding control in their grayscale. I found and measured no observable shifts in color tint for the profiles, even at low brightness. Gradients are exceptionally smooth and free of any banding or tinting. My only complaint is that the white point for the profile is calibrated too warm, measuring consistently about 6200 K. A color temperature adjustment slider is available to use, but I haven’t measured if it could potentially impact the precision of the calibration.

...the Gentle and Cinematic color profiles are calibrated with outstanding control in their grayscale. I found and measured no observable shifts in color tint for the profiles...

Color Accuracy

Although OPPO employs its “full-path color management system” in its Vivid profile, anyone prioritizing color accuracy should instead utilize the discrete Gentle and Cinematic color modes for sRGB and Display P3 content respectively. Thus, I will not be including sRGB and Display P3 for the Vivid profile, and only for the calibrated Gentle and Cinematic profiles.

sRGB color accuracy plots for Gentle profile

sRGB color accuracy for the Gentle profile is overall excellent. There’s some slight oversaturation at max brightness, which is desirable behavior to counteract some glare. Colors are somewhat undersaturated near minimum brightness, but it’s not a huge issue. At around 25% system brightness, colors seem to appear warmer than usual, resulting in the highest average color error within the display’s brightness range.

Display P3 color accuracy plots for Cinematic profile

Display P3 color accuracy is even better. The undersaturation at minimum brightness is not as prevalent, and the rest of the brightness range is just more accurate in general. This is really good.

Overall, the Gentle and Cinematic profiles provide respectable levels of both color and tonal accuracy. Non-critical color and design work can be performed with higher levels of confidence with the OPPO Find X3 Pro than most other phones and non-professional monitors, although the slightly warmer white point needs to be kept in mind.

Non-critical color and design work can be performed with higher levels of confidence with the OPPO Find X3 Pro than most other phones and non-professional monitors...

HDR10 Playback

Measured at 20% APL ≈ 200 nit frame-average light level  (HDR10 1000)

For HDR10 content, you will want to have “Bright HDR video mode” activated under the display settings for improved highlights. Without it, the peak brightness of the OPPO Find X3 Pro will be limited to below 500 nits, which isn’t bright enough to deliver a compelling range of specular highlights.

Before we get into any other observations or measurements, I found that there was a huge difference when watching HDR content within the stock Gallery app compared to in other apps. This is because the stock Gallery app appears to be doing the HDR tone mapping instead of just switching to the phone’s HDR color mode, which is what every other app will do to play HDR content. This is not inherently a bad thing, but one issue with it is that the peak brightness of HDR content is limited to 500 nits (even with “Bright HDR video mode” enabled) unless the Find X3 Pro is in high brightness mode, which only occurs in really bright conditions where HDR content isn’t meant to be viewed in. Thus, my measurements will be based on the phone’s HDR color mode, which will reflect how most consumers will be watching HDR content on their phone.

On one more note, the stock Gallery app does go further with dynamic tone mapping by straying from the PQ curve to lighten color tones in brighter ambient conditions.

The whole point of High Dynamic Range content is in the contrast. The OPPO Find X3 Pro renders HDR10 content with a lift in darker tones so that they appear lighter. This reduces the contrast of HDR content, especially in darker scenes. On the other hand, the midtones and highlights look great, and the measured brightness for 75% PQ of about 750 nits (expecting 1,000 nits) is acceptable for content that is mastered for 1,000 nits. The Find X3 Pro can actually get up to about 900 nits at 100% intensity, but like many other Android phones, it lacks roll-off tone mapping towards the content’s maximum brightness (which is listed in the content’s metadata). This leaves the extra ~150 nits of brightness inaccessible when watching content mastered for 1,000 nits, which includes most HDR content.

In terms of grayscale, the precision of the color of white (or gray) is nice and consistent for HDR content. The color temperature remains close to the D65 standard, averaging about 6430 K with no noticeable shifts in color tint, independent of lightness.

Color accuracy for HDR10 is fine on the OPPO Find X3 Pro, although it slightly misses the full P3 gamut with reds, and there’s a slight undersaturation in greens.

Final Remarks on the OPPO Find X3 Pro

On paper, the display on the OPPO Find X3 Pro may not seem like much of an upgrade over last year’s. However, in absolute terms, it is an upgrade, and overall it’s an excellent display that fixes many of the issues of last year’s model. The new LTPO panel provides an adaptive refresh rate solution that saves more battery, and it prevents color tint differences when the panel switches between refresh rates. The peak brightness remains the same, but its change in tone map behavior allows the Vivid profile to remain more legible than the X2 Pro when viewed outside. Additionally, at low brightness, the OPPO Find X3 Pro looks cleaner with less tint and little-to-no black crush (whereas the Find X2 Pro was a bit messy in both), and the “Reduce contrast” option is also one of the best usability options of this phone for nighttime viewing. Both color and tonal accuracy has improved across the board, lending a more consistent and faithful picture, including within the Vivid profile. And thanks to the new “full-path color management system”, you can now see a more accurate depiction of photos in the stock Gallery and Camera apps within the Vivid color profile.

    OPPO Find X3 Pro
    At £1,099 in the UK or €1149 in Europe, OPPO is asking customers to spend a lot on a smartphone, but the Find X3 Pro's display lives up to the price tag.
Specification OPPO Find X3 Pro
Type

Flexible OLED

PenTile Diamond Pixel

Manufacturer Samsung Display Co.
Size

6.1 inches by 2.7 inches

6.7-inch diagonal

16.7 square inches

Resolution

3216×1440

20:9 pixel aspect ratio

Pixel Density

372 red subpixels per inch

526 green subpixels per inch

372 blue subpixels per inch

Distance for Pixel Acuity Distances for just-resolvable pixels with 20/20 vision. Typical smartphone viewing distance is about 12 inches

<6.5 inches for full-color image

<9.2 inches for achromatic image

Black Clipping Threshold Signal levels to be clipped black

<0.4% @ max brightness

<0.4% @ min brightness

Specification Gentle / Cinematic Vivid
Brightness
Minimum:
2.2 nits
Peak 100% APL:
735 nits
Peak 50% APL:
758 nits
Peak HDR 20% APL:

777 nits

687 nits (1k)
Minimum:
2.1 nits
Peak 100% APL:
740 nits
Peak 50% APL:
806 nits

Peak HDR 20% APL:

886 nits

754 nits (1k)
Gamma Standard is a straight gamma of 2.20 2.00–2.30 2.13–2.36
White Point Standard is 6504 K
6230 K
ΔETP = 3.7
7016 K
ΔETP = 6.5
Color DifferenceΔETP values above 10 are apparent ΔETP values below 3.0 appear accurate ΔETP values below 1.0 are indistinguishable from perfect
Gentle/sRGB:
Average ΔETP = 3.4
Cinematic/P3:
Average ΔETP = 3.1

The post OPPO Find X3 Pro Display Review: Solid Quality All Around appeared first on xda-developers.



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