U2718Q DP and HDMI input inconsistency at green channel - Monitors Forum - Peripherals - Dell Community

U2718Q DP and HDMI input inconsistency at green channel


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U2718Q DP and HDMI input inconsistency at green channel

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I have received my U2718Q and enjoyed with its 4K ability. However, I totally doubt how Dell had calibrated the monitor to have a Delta < 2 for U series monitors. I could not further calibrate the monitor to an acceptable colour representation.

I connected devices to U2718Q from DP and HDMI. On HDMI, the colour representation is great with all visible colour gradient as shown on the image below. (Please pay attention on the green gradient >28, the colour change is visible)

However when I connect at Displayport, the colour representation had a huge change with green gradient > 28 all brightened, making the brightest range on green indistinguishable. (please see below image)

The outcome caused from brightened green channel is the screen will look all greenish as all light grey has a 255 level of green added on it (assuming we represent the colours in RGB level, all neutral light grey say in [210,210,210] will be displayed as [210,255,210]). Or in gamma level, the monitor displays a green gamma at 1.5 on luminance 48%, the rest of colour channels and luminances are ~2.2 and they are great. However, the green channel at bright side caused a serious disaster to the monitor performance.

The most interesting thing is the problem won't happen on HDMI input and only exist in DP input. I have already tested on multiple systems like PS4/PC/Mac and the monitor did not perform correctly with all DP input from all input sources.

I am aware that Dell has replied on a similar thread that U2718Q only supports legacy Windows released 3-4 years ago which is obviously a shame for Dell's most recent sub-flagship product released just for a month. I deeply hope the information captured was incorrect and could be rectified if any.

Now that I have tested the DP input from a Windows PC (instead of a Mac that Dell would refuse to offer support to a Mac user), could Dell take an action to confirm if the DP input function has some defect (on a software side I supposed) and would it be possible to fix it with firmware updates?

I deeply hope Dell could take a serious step to inspect the case as it is not an individual unit problem anymore. I am also expecting a formal reply from Dell and I am happy to cooperate to test and help improve Dell's newest product. Thank you.

All Replies
  • The site has changed. This monitor is supported all the way up to Windows 10.

    The driver DELL_U2718Q-M7DV9.exe also shows this under "Supported Operating Systems".

    Explain in detail how you calibrated the U2718Q. Using what windows computer (model, operating system, video card, video card driver, etc.), specific calibration hardware and software.

    Have you tested using the mDP in port on the U2718Q?

  • I have the same problem as ycw9921133 with my new monitor U2718Q.

    I have tested DisplayPort and mDP and different cables.

    HDMI Port works Fine.

    I have not try to calibrate the monitor so is in factory defaults.

    Win10 64bit

    RX 480 Sapphire

    Asus HERO VII

    Intel i7-4790k

    16GB Ram

    Everything is updated drivers, firmware all the latest.

    Thank you

  • * Open the U2718Q Menu OSD (On Screen Display) page 34
    * Go to Others- Factory Reset
    * Go back to Color. Input Source should be RGB
    * Go to Preset Modes
    * Test green in all Preset Modes =
    Color Temp
    * Then choose Custom Color and tweak the green

  • First of all, all the colors have problem the green is just the worst.

    I did exactly what you described.

    In movie mode the problem is getting worst and in game mode is getting a little better.

    Tested with Eizo monitor test / Gradients 64 shades.

  • You should consider purchasing calibration hardware and software. If you choose not to do this, your options are to return it (if purchased from Dell and still inside the first 30 days from the invoice date) or ask for an exchange.

  • Thank you for the response.

    It has been a week that I have explained the problem to your representative here in Greece and asked for an exchange but no response yet.

    It does not seem to be an isolated issue because others have reported the same problem.

    What if they give me  a new monitor with the same problem?

  • I exchanged the monitor.

    The new one has the same problem.

    Now what????

  • Hi,

    I am just surprised we have friends here. And I am sorry for not keeping the participation in the thread as I thought the thread was dead...

    As a non-professional computer enthusiast, I guess the reason why the monitor blends the transition of the some portion of a colour channel in one brightness (the brightest portion of green in this model) could be due to the insufficient processing power of the monitor chip.

    DP signal may carry additional data stream than HDMI signal and caused the monitor to ignore some of the information from the DP signal.

    Other factors might include the firmware inside the monitor could not process the DP signal correctly or it is just programmed to make this defect.

    I am quite sure the problem can be fixed by just few tuning on the firmware if the monitor chip supports full 255 levels colour range from DP input (if not, more than current...) and if Dell allow us to update the firmware and if Dell is willing to perfect the U2718Q...

    Sorry for the strange English as I am not a native...

    Cheers from Hong Kong!

  • Hi Chris,

    Happy to see the monitor is supporting the latest Windows versions. And all the photos showing are in factory settings.

    For the calibration, I used eye ball calibration with Windows' official calibration tool in "Settings" and also tried the quickgamma. In addition, I also played around with Mac's calibration tool (which is much more detailed but you know, Dell won't support) but as expected, it didn't work. What software calibrations could do at most is to map all the bright colours to lower levels which kills the dynamics of the monitor. Still, all the software approaches did not do the magic. So it is untunable with software. 

    I did not use any hardware calibration since I don't expect to get colours work again by paying extra, and I am not investing one just to answer your coming questions. 

    All in all, my point is I don't expect to do extra things to revive the brightest part of green channel. And it is really unrecoverable by a typical user.

    I haven't tried the mDP input yet. I have neither source with standard DP input nor a mDP to mDP cable myself. I guess the supplied one (mDP to DP with a mDP source) should do the best.

    Please could you tell if the Dell's claim on Delta < 2 is only applicable on certain input(s)? I am expecting a quality monitor could show about same colour range from any input. And with Dell's guarantee, all ports may have understandably very subtle visible difference but not like this.

    For my PC spec, I am using a Microsoft Surface Pro 4 with Windows 10, Intel Graphics 520, official stock video card driver (Microsoft restricted to update the driver to intel's provided one, hope this is not to blame) plus an expensive Moshi 4K mDP to HDMI 2.0 active adaptor for HDMI test just for this issue... I guess this is one of the most generic choices as a test source, and hope you would inspect the issue further in details. (I also tried a MacBook Air 2016 to hope for miracle but again, it didn't work. For more HDMI testing, I also tested with PS4 Pro for popularity)

    Please just tell me to supplement any information if you need. Thank you!

  • It should apply to all inputs but, note we stated in the User's Guide, "average" =

    But again, to be exact to your viewing, you need to hardware calibrate it using calibration hardware and software.

  • First of all I do not think is fair to invest hundreds of euros for calibration equipment, for a monitor that claims factory calibrated. Anyway!    

    I discovered that if I change Pixel Format from  RGB 4:4:4 Pc standard to YCbCr 4:4:4 in my AMD drivers settings, monitor changes Input Color Format from RGB to YPbPr  and YES! Color gradients are beautiful in DisplayPort.

    Any idea Why???

  • Yes I've heard of similar solutions to make colours displayed correctly on some Dell's monitor models.

    But the point is, Surface Pro 4 does not offer such display settings...

    Would Chris suggest if Microsoft's devices are supported or only the operating systems so the blame is put back on customers?

  • Thanks for proofing U2718Q units are "not faulty", and insist it is customers' responsibility to calibrate the monitors even with such a big gap on the colour displayed.

    So, if I buy a colorimeter and finally figure out the mentioned issue is not solved with hardware calibration, will I receive a refund due to this case? I just need a confirmation that such problem is solvable. And I hope not to create further problems.

    If you know, please tell me if hardware calibration is calibrating the internal colour mapping of the monitor instead of output stream from display cards.

    Thank you and sorry for bothering you again.

  • I do not have a clue what is going to happen with hardware calibration, but I have a suggestion for you.

    In your monitor's menu try changing the Input Color Format from RGB to YPbPr  and see what happens.

    And Chris we need your input.

  • My Surface Pro 4 does not allow to change colour format...

    Let see whether Chris could help...