BenQ PD2720U Not reaching advertised colour gamut coverage?

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  • #28844

    Philipp Mochine
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    Check which color format is output through HDMI, try to match it in input format in display.

    Can you elaborate on how to do this?  I’m on a Mac and I’m not really sure what you mean. How can I check which color format is output through HDMI? Over the monitor itself or the OS? And where? 😅

    Thank you!

     

    PD2700U is sRGB.  ONLY sRGB. A very good one for its price I must add. All seems fine in your calibrated display (through DisplayPort)

    PD2720U is the low cost AdobeRGB version (PG > SW > PD > BL …). It’s a different model with different price.

    Omg! Didn’t notice the 2720U! I thought this would be also my monitor! Thank you for telling me the difference.

    I just have switched back to HDMI, but I still get bad ΔE 🙁

    #28845

    Marcel
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    As Vincent said, PD2700U is only advertised as covering 100% SRGB/Rec. 709. So 83% P3 is actually pretty good for a SRGB display. My SRGB displays only reach p3 percents in the mid 70’s.

    Display port at 30hz isn’t the worst. If your only editing/viewing 24-30fps footage that’s all you really need.

    I wonder if a new DP 2.0 cable would make a difference?

    You said your HDMI isn’t a regular HDMI its a HDMI to usb c. Maybe there’s something weird happening in that conversion process. Guessing macs don’t have a regular HDMI port anymore you could test?

    Or might just be SOL and have to settle for lower refresh rate or poor calibration until apple fixes what they broke. 😛

    #28846

    Wire
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    #28847

    Wire
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    Check the monitor’s config for RGB vs YCbCr (aka YPbPr in analog HDTV, or sometimes YCC)

    It comes down to whether the Mac sees the display as “HDTV” or a graphics display. In TV mode (YCbCr), there are several concerns due to compatibility with analog TV:

    A) Limited signal range — the signal is conveyed as luminance and color difference not R G B. The data values for each of Y (luminance, diff green) Cb (diff blue) Cr (diff reg) are computed as weighted sums of the RGB. Further, it’s very common for the signaling levels to be restricted to from 0.255 (assuming 8-bit) to leave headroom and toe-room for analog TV signaling effects.

    B) Color pixel subsampling — Motion video signals typically send color detail  data a fraction of the luminance detail. This is where the designation 4:x:x come from. For every square block of 4 luminance pixels (grey), the color is sent in a fractional amount, so 4:4:4 is color at same resolution as luminance,  4:2:2 is 2 pixels of BR-diff spread across 4. The most common by far is 4:2:0 which further reduces color info. JPEG Image compression starts with this idea as a baseline. You can see that pixel level graphics such as text rendering and line art might not render will when color data are cast out, but in motion video (classic TV and film) you also never miss it, and this in baked into the earliest deployments of TV dating to origins in 1950s. Modern systems and SW may translates back and forth so it’s always very media / format / program specific which signaling applies — there’s no One Right Way. Safe to say PC graphics are traditionally RGB, but the PC display was always a re-purposed TV set, and today’s, devices fully marry PC and TV technology.

    And for completeness..

    C) In HDTV there is the trait of “overscan” which dated back to imprecision of pixel addressing on face of analog CRT: the TV set always overshot the raster past the edge of the tube face a little to fill it. So like the safe zone a cinematographer users when framing shots to ensure mics and other set artifacts are out of the finished frame, overscan dealt with ensuring that picture content fit on TV. In print pre-press it’s called “bleed” when an image is marginally oversized to be sure than when paper is cut into the finished product, ink goes edge-to-edge.

    When connecting a display with HDMI, all these concerns come into play because of what the format owes to analog TV.

    A PC / Mac / game console tries to hide these details because they are inscrutable to end-users, but the price is that they can’t get it right for every situation.

    So content data, the viewer app, the OS, the graphics adapter, the ports, the cable, and the display all can affect what happens!

    Check your display config to see if you can force RGB vs YCC mode when connecting by HDMI.

    #28850

    Philipp Mochine
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    Yeeeeeeeeeeeeah 😍

    Thank you for the link @wire! I managed to get it to work! (See the attachment)

    But it wasn’t easy! Because macOS Big Sur had big changes so the link by @wire didn’t work completely.

    If someone is reading this in future, here are the steps:

    1. Connect the problematic display.
    2. Download and run this script in Terminal by: “ruby patch-edid.rb”
    3. This creates a folder like DisplayVendorID-10ac/DisplayProductID-4080
    4. Now it gets different, because Big Sur doesn’t allow you to write into critical folders, you have to copy the whole display folder like this: sudo cp -R /System/Library/Displays /Library/
    5. Now go to /Library/Displays/Contents/Resources ( and not to /System/Library) and create a copy of the folder Overrides. Just to be safe
    6. Now drag and drop the created folder by the patch into Overrides
    7. restart

    Since with this change, my HDMI cable works.

    Attachments:
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    #28855

    Wire
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    Holy cow, It worked?!
    I have not used that myself. I expected offer of only clues for find way out of config quagmire.
    Happy  it helped.
    Pls pay forward, thk u

    #29825

    gioriv
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    Hello everyone!

    I’m in the middle of just learning color calibration, I just recently got the same monitor as you. I have to mention that the monitor for being a software color calibrated is still pretty good to  me. What I have notice as well is that environment does matter a lot when using any of the calibrated tools, sometime room is too dark or too bright. I got pretty good close as advertised for the monitor, I link my calibration results.

    I’m using the SpyderX ELITE!I

    Analyze the monitor on 3 different color profile presets; REC709, AdobeRGB and Display P3. After all of that I calibrated the monitor on user mode. Like I mention, I’m just learning and by that I would no be the most qualifying person to discuss on this matter, but I just wanted to share my results.

    Attachments:
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    SpyderX Pro on Amazon  
    Disclosure: As an Amazon Associate I earn from qualifying purchases.

    #29833

    Vincent
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    Datacolor reports are useless, every single page.

    Use DisplayCAL with that SpyderX (install ArgylCMS USB driver on Windows will disable Datacolor driver), choose GB-LED phosphor correction “mode”, since SpyderX is a very limited device with just a few built in corrections.
    Remember to check contrast at your desired white level with DisplayCAL, datacolor report shows an extremely mediocre contrast level at 100-120cd/m2, unacceptable IMHO.

    #29834

    gioriv
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    Thanks so much for your clarification and advise. I purchased the SpyderX ELITE beacues it was on 50% OFF. I couldn’t justify the price for theci1Display Pro since I’m just learning. I guest it was better to spend the extra $100.  I will get into this today and make comparison, will post results if I’m able to. Again, thanks!

    i1Display Pro on Amazon  
    Disclosure: As an Amazon Associate I earn from qualifying purchases.

    #29835

    Vincent
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    Before purchasing i1d3 use Spyder X with DisplayCAL using suggested correction/mode. Measure the same things as in Datacolor software but with DisplayCAL, check that contrast issue, ~600:1 native white at 120cd/m2 seems faulty unit or useless model (typical bad quality panels from benq with uniformity compensation that cannot be turned off, but that happens on SW models, no PDs… anyway, check contrast @120cd/m2 with DisplayCAL). Other owners have not reported such issues (or I do not remember)

    #29836

    gioriv
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    Thanks definitely I will, I actually tried but let everything on auto. Also on the mode I only have either:

    LCD PFS Phosphos WLED, RGB LED  / LCD GB-r-LED  /  LCD White LED  /  Generic

    On the correction is set to Auto(None) I;m kind off confuse on those 2 section.

    #29837

    Vincent
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    LCD GB-r-LED, read this thread, there is a spectral power distribution plot of PD2720U. It’s a GB-LED.

    #29838

    Marcel
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    Hello everyone!
    I’m in the middle of just learning color calibration, I just recently got the same monitor as you. I have to mention that the monitor for being a software color calibrated is still pretty good to  me. What I have notice as well is that environment does matter a lot when using any of the calibrated tools, sometime room is too dark or too bright. I got pretty good close as advertised for the monitor, I link my calibration results.
    I’m using the SpyderX ELITE!I
    Analyze the monitor on 3 different color profile presets; REC709, AdobeRGB and Display P3. After all of that I calibrated the monitor on user mode. Like I mention, I’m just learning and by that I would no be the most qualifying person to discuss on this matter, but I just wanted to share my results.

    Thanks for sharing! Guess this further confirms these are 93% P3 monitors not the 96% BenQ claims they are.

    #29852

    Алексей Коробов
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    A funny fact: gamut depends on color temperature. I’ve met some iMacs that holded 100% P3 at native WP ~7150K, but they showed quite less at 6500K. Probably, you can achieve 100% P3, but at crazy WP.

    #29854

    Wire
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    ure. I’ve met some iMacs that holded 100% P3 at native WP ~7150K, but they showed quite less at 6500K. Probably, you can achieve 100% P3, but at crazy WP.

    There’s possibly a misunderstanding here… Because we can’t adjust the native display temperature on an iMac, we only can only use the GPU to redistribute the 24 bit space of color numbers, then if we shoot for a non-native white-point with a GPU alignment, an amount of the native space which corresponds to the white-shift is commandeered to make the shift and is therefore unavailable for rendering. Basically an edge(s) of the gamut region get lopped off.

    But maybe you don’t care because white balance is a far more distinguishing trait for images than edge gamut. Nobody can really tell how far off a few points of red in a bright flower, and many images have no red at all! But Most images have an overall balance which everyone can notice. So the trade-off may be well worth it.

    Except that, IMO, we tend to tolerate white bias in an absolute sense quite well as long as the display doesn’t wildly disagree with its environment, or we are comparing displays.

    I’ll give you another example, totally aside, but related: TV and theater nerds are wild about contrast ratio because displays are typically seen in dark surrounds, especially in production. Because until recently displays were reasonably brightness limited, then contrast is a matter of how dark the display goes, with a lower-contrast display showing a grayer black level in a dark room. In an office, no one would notice. In a TV studio, everyone is like that low-contrast unit with IPS glow stands out like sore thumb. In days of CRT, the black level was set to match surround conditions using a PLUGE pattern, and today we inherit the attendant variance in settings across production domains in the form of the BT.1886 recommendations.

    FInally, in my opinion a 7000ish white point is far from a crazy white. Apple chooses it because to most people in most circumstances it looks a little cleaner and fresher. And when compared against PCs which historically have had very blue / green displays because they are sold for high-brightness work areas, and Apple (the instigator of desktop color management)  didn’t want their appliances to look too dull.. PCs, like TVs, were sold on mall shelves under florescent lights and everyone responds to brightness. At same time, Mac has always been the odd-man out in an office-full-of-PCs world, so a little bluer bias makes sense. It even makes sense purely as a matter of taste. However, you may notice that Apple has converged on D65 for iPhone / iPad which have a very small, very bright screen and which are sold as defining high-quality devices in market of devices where display-color is anything-goes as long as it’s mobile. Samsung sold disgusting green displays for a long time after Apple had settled on D65.

    Apple has been careful enough about this  that iPad has become a defacto color reference for anyone in production of anything.

    In last several years, mobile device color balance has entered this whole other realm of mood-setting (night-shift, etc) as part of a “healthy” circadian regimen and other juju like blue-light wrecks your eyes.

    P3 has the desirable trait of a somewhat wider-gamut and can produce noticeable response improvement, such that when look carefully, you can mosdef see it.

    But in a world of web color, what most people see is distorted color because their content is not being mapped into their wide-gamut display properly. WCG has made color worse for many users. But no one minds because it’s just sam damn colorful!

    Pretty much no-one can tell if a properly displayed P3 image that uses the gamut outside of 709 is 3% shy of spec. To argue about it is to go back to age of audiophile golden-ears.

    So yes, hold BenQ to account if you must, but in practical sense a 3% measured vs spec delta is pretty much noise unless you are doing a study of device response. If you aren’t studying device response, you are missing nothing.

    A well-aligned 709 display will produce more satisfying and colorful renderings that a misaligned wide-gamut display.

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