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Old Dec 21, 2012, 07:36 PM   #1
Tri-stan
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New iMacs Screen Black Crush?

First impressions seeing a 27 inch iMac in Apple store:

I managed to get on to a new 27 inch late 2012 iMac here in the Uk and was able to have a good play around on it to see how it performs. Overall it worked well, although adobe elements was laggy, slow to zoom on occasions even on a white screen "checker boarding" and to re-size its window was laggy. That machine was running a 675mx gfx and a standard 1TB HHD which was painfully slow to use. Other than that it was quite impressive apart from what I am reviewing below.

This is what I am most concerned about, it is the apparent black crush exhibited on the monitor. Now this may just may be software in OSX with its photo viewer but I did also notice that fonts in Safari were blotchy and had too much blue saturation which was strange.

So to quote my findings on this:

Below there are three images, The first a reference of the entire image "upon double clicking it can be downloaded at full size to test if need be" The second a close up of the most affected area "note it looks just like this in windows photo viewer as well" and the third a picture captured on my s3 of the iMac display using is own photo viewer as standard.

Analysis of affected area between "iMac osx photo viewer" and "u2711 win 7 os photo viewer":

The affected area on the iMac shows in the most black areas of the screen there is a loss of detail. Where there is more information on the u2711 the iMac seems to crush the blacks. So on the image showing the fan unit with the orange dot, "the lower portion of that unit which is darker" when displayed on the u2711 it shows fan supports and a radiator behind where the iMac's equivalent image shows just black.

Now I know using a camera to capture the information on the screen in the third photo will reduce the information held within the image but this is pretty much how it looked in the store. I have had problems like this before with srgb and rgb images on my wide gamut monitor but even using an srgb image held within the internet page it shows the information but just not on the iMac.

Questions:

I have got my computer set up so that srgb/rgb images all work across photoshop, downstream from chrome and windows photo viewer which all display the correct colors, is this even possible on the imac? I suppose you just can't use rgb images which is a shame.

I just don't understand this black crush problem if anybody can help?? Colour gamut can be really confusing at times!


Reference image
Thumb resize.


U2711 "same as what it looks like in windows photo viewer not a direct photo"



Late 2012 imac "what is seen in the mackintosh's photo viewer as a photo taken on my s3"
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Last edited by dejo; Jan 3, 2013 at 01:05 PM. Reason: Please use [timg] tags for large images.
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Old Dec 21, 2012, 09:38 PM   #2
wessew
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It appears as if the iMac screen needs to be calibrated. Not only do you see black crush but there is also faint white blooming. This would include the gray scale which needs to be set to ramp evenly from deepest black to whitest white. However, it appears resolution is equivalent.
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Old Dec 21, 2012, 11:10 PM   #3
bobright
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maybe it's just me but I'll take a little black crush over a badly light bled panel any day

though I don't use Photoshop and have my work rely on perfect colors etc
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Old Dec 22, 2012, 04:38 AM   #4
Tri-stan
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This is a total deal breaker if the monitor exhibits that about of black crush. I am buying this machine for mainly the screen being the number one selling point and number two being that it runs osx. I just can't believe that this is how it is ment to be out of the box, currently I have got less black crush on my Samsung S3 phone screen. Is it true that the iMac has become just a toy? I need to use this machine to actuary work on not for facebook etc.

I was not able to test the image on a decent version of photoshop. If Somebody was able to put the first image on cs6 and could tell me weather or not the same amount of black crush was apparent or not? This will be a true test because if photoshop's automatic colour settings means that it still can't display the dark grey's meaning black crush is still experienced and now, "well spotted white blooming as well" then good by iMac.

Please tell me I am wrong and this is just software?
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Old Dec 22, 2012, 05:24 AM   #5
digitalfailure
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I've always found that iMacs have the default brightness cranked up way to high out of the box and its often adjusted even more to allow the screens to still pop under all the shop lighting. If colours are important to your workflow, you'll calibrate the screen before use in a decent environment anyway.

So get one home, calibrate it and if you don't like it then send it back under the return policy. You'll have lost nothing but a couple of days.
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Old Dec 22, 2012, 06:16 AM   #6
intz2nu
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I am by far no photo expert or monitor expert, and I also don't really know what "Black Crush" is either. However I think I am almost positive in thinking that this is in relation to color differences from OSX and Win7. When I had first switched from a Win machine to a Mac (both a Macbook Air and a 2010 iMac 27") I immediately noticed color differences of both Operating Systems. I can't say if its the OS or the OS photo viewers but on a Mac OS a lot of things seemed a bit more on a yellow side when compared to a Win OS. I honestly thought things was completely south of being a new Mac user cause of how my everyday photos and frequently browsed sites would look on the Mac OS vs a Win OS.

That being said I installed Win7 through Bootcamp on the 2010 27" iMac and once all the Bootcamp drivers were in place and Windows was successfully installed I was gratefully happy to see that things looked to me what I would call "normal" once again when I was using Windows on my iMac. The white looked white and everything looked as it would on any Win machine. I somewhat think its something to do with the Mac OS being Win OS through Bootcamp on a Mac previews photos and websites as they normally would display when on a Win machine. I am also no expert in this either with regard to it being either the OS or the computer but I do know that Windows installed using Bootcamp on all the Macs I had didn't display images or websites with color problems. They looked and appeared as they would when on a Win machine. This is why my conclusion and guess is that its a OS issue.
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Old Dec 22, 2012, 02:57 PM   #7
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Quote:
Originally Posted by Tri-stan View Post
This is a total deal breaker if the monitor exhibits that about of black crush. I am buying this machine for mainly the screen being the number one selling point and number two being that it runs osx. I just can't believe that this is how it is ment to be out of the box, currently I have got less black crush on my Samsung S3 phone screen. Is it true that the iMac has become just a toy? I need to use this machine to actuary work on not for facebook etc.
Calibrate your screen.
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Old Dec 22, 2012, 03:19 PM   #8
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Quote:
Originally Posted by wessew View Post
It appears as if the iMac screen needs to be calibrated. Not only do you see black crush but there is also faint white blooming. This would include the gray scale which needs to be set to ramp evenly from deepest black to whitest white. However, it appears resolution is equivalent.
Well evenly is a strong word there. Gamma 2.2 isn't exactly even. It doesn't have that many values allocated to deep shadows in a range normalized 2**8, so this is a strong statement. I can't think of a single display on the market that's absolutely perfect on shadows. It's quite possible to see clipping at 0-2 or 0-3 in photoshop. Typically you shouldn't have problems past that. The biggest fallacy on here is the idea that a custom profile will absolutely fix this.

A custom profile or calibration updates the output response instructions, but most of the software/colorimeter combinations have trouble with extreme shadow values, and the factory is the only place that can truly calibrate these values at a hardware level. I mean there are things that the software can do to attempt for a better 0-255, but it's quite a bit more limited than this forum wishes to admit. It sets a target. It measures. It generates a small matrix for adjustments. You can then verify with further measurements how close it came to meeting the targets, and the measured behavior is included in another part of the profile so the system knows the capabilities of the display in its calibrated (sort of) state.

I just don't want people to think this will always resolve every problem. If they're trying to determine if a display should be returned, it's best not to rely on the idea that this will fix it all later. The OP would be best off doing this within the return period to ensure it will meet his needs. Even if you get a really good display, proper measurement is optimal.

Quote:
Originally Posted by bobright View Post
maybe it's just me but I'll take a little black crush over a badly light bled panel any day

though I don't use Photoshop and have my work rely on perfect colors etc
They're independent of one another. Backlight bleed has been seen in some of these.
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