Previous 1 2 3 4 5 Next 321 Replies Latest reply: Jul 9, 2009 11:41 PM by Stephen Heward Go to original post Branched to a new discussion.
  • Fred Williams1 Level 1 Level 1
    My third 24" white iMac arrived and after three days I'm sending it back. This unit was better for uniform screen brightness but far worse for the yellow/brown tinting in the middle of the screen. Also, none of the units I've tried can reduce the display brightness to an acceptable level for screen calibration with a colorimeter without the use of the third-party Shades". I'm giving up on the 24" display until some display changes are made at Apple..
  • Arielle The Dog Level 1 Level 1
    I'm not so sure that the gradient defect on the 24" aluminum iMac screens is due to the panel itself or the back lights. There may be nothing wrong with the display itself and the problem may lie somewhere else. Try two things:

    (1) After pushing the power button, observe the grey startup screen -- the one with the spinning wheel. Does the illumination look or measure more uniform than when the machine is fully started up?

    (2) Start up the machine while holding down the D key. This brings up the hardware diagnostics screen. Select your language and proceed to the next page. The background should be a solid blue. Do you see or measure nearly as much variation across the screen as when it is booted normally? (It's a good idea to go ahead and do the test anyway to check out your memory, etc.)

    In both of these cases on my machine, the screen is very nearly uniform, and much better than when the machine is fully booted up. In both of these cases, and especially the second one, the display is probably working without a lot of the normal software and firmware in effect. My theory is that the problem is with firmware or software, in other words, something that could be fixed through software or a firmware update. And if this is true, why wouldn't Apple be aware of this?

    I work in IT and have seen hundreds of cheap Dell business class displays, and none of them have ever had a defect as severe as this .
  • rainydays357 Level 1 Level 1
    1.) I'm not sure about the difference in illumination but the yellow tint is certainly there. This is when I first discovered it, when I booted the machine up for the first time.

    2.) Blue seems to mask the problem a lot. This happens if I choose a blue (0,0,255) wallpaper in OS X as well. The yellow tint is still there in the hardware test even though it isn't as noticable because the grey area is only in the middle.

    So I actually think it's safe to say that the issue is in the display. It can't be an issue with the GPU or drivers because that would not show like that. And booting Windows makes no difference.

    You are right. I've seen many much cheaper displays that were more uniform. I'm really trying to live with it here. I've been working with a website all day and I'm constantly reminded of it. It's not like I'm looking for it all the time.

    By the way, I have made a thread about this with a poll over at macrumors so please share your experiences there.

    It's interesting to see that 73% report that they don't have this issue. It's either that all of us in this thread has incredibly bad luck, or simply that those people are unable to see it.

    It's also interesting the one person has reported that he got a good screen with a replacement. So there's got to be good screens out there. The question is how many times you have to replace it to get one. And if you finally get one it might have dead/stuck pixels.

    I think I would prefer a couple of dead pixels over this though. At least if they are in the border.
  • Todd Ryckman Level 1 Level 1
    I had a good chuckle reading the thread at macrumors. As I stated in an earlier post, it's one of those things that most people wouldn't notice unless they were specifically looking for it. Unfortunately, once you notice it you can't stop focusing on it. At least for me. My wife sees it, but says it's so subtle that I must be nuts for thinking twice about it.

    A number of people have stated that they visited multiple stores and examined a numerous displays. They report all of the displays have this issue to one degree or another. I believe them and this would indicate it's an issue across the 24 inch line.

    I have decided to keep my machine because it is perfect in every other way. I chalk the problem up to me being way to anal. I would have never even noticed it had I not been cruising forums looking for possible problems in the first place.
  • Arielle The Dog Level 1 Level 1
    The color problem is probably a completely separate problem, independent of the gradient problem, and falls into the more usual kinds of display problems. I have the gradient, but absolutely no color inconsistencies.
  • rainydays357 Level 1 Level 1
    I keep thinking that I'm too picky as well. But then I take a seat in front of my cheap Samsung 22" TN panel and I realize that the only problem it has is a slight fading in the upper corner, which is barely noticeable unless I view it from an angle. The whites are white across the whole screen.

    So how come a cheaper TN display is better than this obviously more expensive H-ISP display?

    Now movies look great on the iMac. But that's not what I bought it for, I bought it primarily for my work which includes a lot of graphics design. The panel is clear and crisp and would have been really wonderful to work with if it hadn't been for the yellow tint.

    I'm not sure if I can live with this for 3 years. Perhaps I will get used to it. But I'm guessing that I won't since it's bugging me so much already.

    I will call Apple on monday and talk to them. I really want to know what my chances are of getting an iMac without this issue.
    But I guess that Apple as usual won't admit that it's a widespread issue even if they know it is.
  • karora Level 1 Level 1
    I also had this problem, with pure white on the left drifting to muddy light yellow on the right, most noticeably on white backgrounds, such as iCal, Safari or Mail. The menu bar ran from light gray (left) to darker yellowy gray on the right.

    Accidentally, I came across an application called Profile First Aid in the ColorSync Utility, and I ran this to repair permissions, having no idea of what it could or could not do; and I found that it did make a difference (I am running Color Profile iMac 01). There were quite a few permissions that needed repair. I can still see a slight variation over the screen, but it is now at an acceptable level, and I suspect is caused by ambient light and
    seating position -- on such a large screen, light reflections would surely vary depending on the point of viewing. I can make one side seem lighter or darker simply by moving my head to one side or the other.

    I then made a complete page of one color (by opening a blank spreadsheet to cover the whole screen, coloring it various colors in turn, and turning off the grid each time). I found that the color consistency was excellent, given the slight variations caused by ambient light.

    This last test convinced me that it is not a screen problem, though how this could be a software problem is hard to

    I had also previously downloaded all the software updates available (seven in all, I think) since I bought the iMac yesterday, and it might be that one of these did the trick. Again, can't think why.

    I was going to return my iMac tomorrow, but no longer.

    Hope this helps somebody. It makes no sense that this should be the answer. If anyone could suggest how this or any other software fix could be working, could they reply?

  • rainydays357 Level 1 Level 1
    No it makes no sense that it should be the answer and I don't think it is either, because for me this did nothing.

    Also, consider the fact that the issue is there when the computer boots. This is before any profile has been loaded. Also, the issue is there in Windows as well.

    I would be so happy if this was possible to solve using software, because the computer works amazingly well and is even more quiet than the first one I got. But I'm afraid it's not possible to fix it with software, unless the display is "patchable" somehow, which I doubt could solve it anyway.

    However, different profiles will make the issue more or less visible. So perhaps it got better when the profile you are using was fixed?
    A profile cannot affect different parts of the screen, so obviously it cannot correct the yellow part of the screen.

    It might be that somehow your screen just got better for some reason though.
  • i2eyeruben Level 1 Level 1
    Yup..... I have the same issue from the bottom lighter and darker as you go up. But after spending $1500 I should have an even brightness on the screen. I'm taking mine back tomorrow.
  • rainydays357 Level 1 Level 1
    I'm afraid the uneven brightness can't be fixed by replacing it. However, it seems like not all units has the yellow tint. So if you don't have that, consider yourself lucky.

    I'm waiting for my second replacement right now, praying that it won't have the yellow tint.
  • Peter Gutbrod Level 1 Level 1
    Browsed this forum as I was about to get one of the new iMacs as a small second workstation to my MacPro for DTP. It was a real shock to read the 20" iMac now has a cheap 6 bit TN panel, which disqualifies it for my purposes, and the 24" has that serious issues with backlight homogeneity and color casts. I've now delayed any purchases until either the iMacs get better LCDs or I can afford a second MacPro.
    Back to your workaround for the backlight homogeneity issue by pushing up the backlight brightness and then tune it down via monitor profile. This is usually a bad way to do, as you loose quite a bit of color depth this way.
    Example: An ideal 8 bit panel can display 256 steps for each red, green and blue, thus 256 steps of grays (identical values for R, G, B) from pure black to white. If you have to tune down the brightness via the monitor profile by 50% (a bit extreme, but just to better demonstrate the effect), white is now translated to a RGB value of 128/128/128, which means you have now left only 128 steps from pure black to white. It is much more likely you will see banding on a gradient now.

    For me it looks like Apple now uses ultra-bright LCDs in the iMacs originally build for watching TV/video. These are ways too bright for computer work, especially color critical work, and if you dim the CF-bulbs in the displays down to an acceptable brightness level (120-140 cd/qm), the background brightness becomes uneven. Really sad.


    Message was edited by: Peter Gutbrod
  • jfmclaughlin Level 1 Level 1
    i wanted to upgrade from my old imac g4 800mhz to the new imac. at first i was very suspicious about all the glare issues etc, but decided to buy it anyway. this is what i've found, 1- the monitor looks good when viewed under "normal room lighting" the color and contrast are have a "film-like" look to them. 2-the monitor calibrated without a hitch using the spyder 2 pro (which was another concern of mine). 3- prints on my epson r1800 looked about as close to the image on the monitor as you could expect (using photoshop cs3)4- the images were sent to my website and also emailed to myself and once again looked very good to the point where myself and two other photographers felt that we couldn't understand what some of the negative press was about. mabye your experience is an isolated incident reguarding a batch or some type of lot. i am pretty picky, so i gave the monitor the full scrutiny when i got it home. i hope for apple's reputation, that your incident is isolated. i am very curious as to the results of your questions, good luck john f mclaughlin
  • The Looby Level 4 Level 4
    Peter Mars wrote:
    Is anyone else seeing this? My 24" iMac Aluminum screen is a full f-stop dimmer on the right side! I am a photographer and so I took a light meter reading of the screen, with desktop image set to light gray solid background.

    Yep, exactly the same pattern -- but a little worse. I'm not a photographer, but my camera is a light meter (put it in aperture priority mode with a fixed ISO 'film' speed, and magically, shutter speed becomes a direct linear measure of luminance).

    My 24" iMac has a left:right luminance ratio of 2.5:1 (about 1.3 f-stops). Three of the four iMacs at the local Apple Store measured the same or a little worse. The fourth showroom sample measured 3.7:1 -- nearly TWO f-stops! In every case, the left side of the screen, at minimum brightness, was significantly brighter than the right side of the screen at maximum brightness.

    Furthermore, the gradient is worse than the simple max:min ratios would suggest. Most of the brightness change is localized in the left half of the screen -- followed by a more gradual roll-off from screen-center to the right edge. There's an intense vertical "hotspot" covering the left 1/4 of the screen. Again, I'm no photographer -- but I won't accept a display that's constantly trying to burn-out my left eyeball. Surprisingly, photos and video are nearly tolerable; the hotspot is at its worst when viewing dark text against a light background right now!

    ...*"The quality goes in before the name falls off."*


    Background: Solid Aqua Blue

    Background: Solid Gray Medium
  • omarxcs Level 1 Level 1
    Has Apple mentioned ANYTHING official in regards to this issue?
  • The Looby Level 4 Level 4
    Has Apple mentioned ANYTHING official in regards to this issue?

    Nope, nothing I'm aware of in response to this issue, but I did happen to stumble across these tasty "official" morsels directly related to the issue:

    _*20" iMac:*_

    _*24" iMac:*_

    *Apple Product Environmental Specification*

    Date: 8/07/07
    Product: 24-inch iMac
    Part Number: MA878

    ... \[snip\] ...

    *8.0 Ergonomics*

    Visual ergonomics is an important concern to computer users. It affects user comfort and performance. Apple designs, tests and certifies our displays to meet stringent visual ergonomics (front of screen) criteria.

    ...or not,

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