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Author Topic: X-Rite i1 Display Pro on HP LP2475w and Win7 results in dark images  (Read 4111 times)
Ownaz
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« on: November 16, 2012, 01:06:31 AM »
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Calibrating my MacbookPro (non retina 2009 model, OS 10.6.8 ) and an attached cheapo Mitsubishi 27" monitor with the Display Pro gives me usable results. However, using the Display Pro on a Win7 machine with the HP LP2475w makes images appear too dark.

It is not the issue of using Version 2 vs. Version 4 profiles which results in very dark images when using the Windows Photo Viewer.

Images like the current Homepage photo appear bright on my Mac setup but too dark on my Win7 PC where I can barely make out the shadow areas and the barn. Shadow areas darker than this appear completely black, no matter how much I turn up the brightness or contrast of my screen.

Has anyone encountered this problem before and knows a fix to this?

Thank you all
« Last Edit: November 16, 2012, 01:18:47 AM by Ownaz » Logged
Simon Garrett
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« Reply #1 on: November 16, 2012, 10:15:51 AM »
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Not quite sure I understand the sentence "It is not the issue of using Version 2 vs. Version 4 profiles which results in very dark images when using the Windows Photo Viewer."  What results in dark images?  However, I recommend using only v2 profiles, as quite a lot of software can't cope with v4 (including Lightroom, for example).

Just to check, if you view the image at http://www.lagom.nl/lcd-test/black.php, how far down can you distinguish?  On my HP LP2475w, calibrated/profiled at a brightness of around 100 cd/m2 I can distinguish down to about 3.  If I understand you correctly, you can't go down anywhere near that low. 

At the white level (http://www.lagom.nl/lcd-test/white.php) I can distinghish 253.  I get the same results with another monitor. 
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lfeagan
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« Reply #2 on: November 16, 2012, 10:30:27 AM »
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When you run the calibration, you can choose what luminance level you are targeting. You may have chosen something like 80cd/m^2 and may be losing the contrast necessary to distinguish those dark areas. Increasing the luminance target for the calibration (and changing the brightness settings before) may help. Try something like 150cd/m^2.
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Tim Lookingbill
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« Reply #3 on: November 16, 2012, 11:23:54 AM »
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Images like the current Homepage photo appear bright on my Mac setup but too dark on my Win7 PC where I can barely make out the shadow areas and the barn. Shadow areas darker than this appear completely black, no matter how much I turn up the brightness or contrast of my screen.

That LuLa image you referenced doesn't have an embedded profile so it appears dark in color managed Safari on my calibrated/profiled to 100 cd/m2 Dell LCD attached to a Mac Mini running OS 10.6.8. Drag & dropped that image onto my desktop and assigning sRGB in Photoshop lightens the shadows considerably.

You're Win7 system image viewer must not be color managed and is assigning by default your Display Pro profile or something else. When I assign my i1Display profile to the LuLa image in Photoshop, the shadows go dark where you indicated. See these intructions on that Lagom site...

http://www.lagom.nl/lcd-test/display_settings.php#color_management

This is what I'm seeing...

« Last Edit: November 16, 2012, 11:39:40 AM by tlooknbill » Logged
Ownaz
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« Reply #4 on: November 17, 2012, 10:10:56 PM »
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Thank you all for your replies.

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Not quite sure I understand the sentence "It is not the issue of using Version 2 vs. Version 4 profiles which results in very dark images when using the Windows Photo Viewer."  What results in dark images?

If you use the profiling software in "simple" mode it automatically creates Ver.4 profiles which was an issue for me in the beginning as many applications showed me completely dark images. I am not in the office today where my Win7 machine is, so I'll report back tomorrow how far i can distinguish the black and white levels. On my Mac setup at home it is the same as for you, 2 for black and 252 for white

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When you run the calibration, you can choose what luminance level you are targeting. You may have chosen something like 80cd/m^2 and may be losing the contrast necessary to distinguish those dark areas. Increasing the luminance target for the calibration (and changing the brightness settings before) may help. Try something like 150cd/m^2.

Both of my setups are calibrated to 160cd/m^2

As for the (non)embedded profiles: I looked at the image in chrome (not color managed), IE (not color managed) and safari (color managed) and the result is always the same. Saving and viewing it with Win Photo Viewer also yields the same results. I will try applying a color profile in Photoshop and see what results I get.

I will be in the office again tomorrow where the Win7 machine is located so I will report back on my findings.

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Ownaz
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« Reply #5 on: November 19, 2012, 02:47:08 AM »
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Just to check, if you view the image at http://www.lagom.nl/lcd-test/black.php, how far down can you distinguish?  On my HP LP2475w, calibrated/profiled at a brightness of around 100 cd/m2 I can distinguish down to about 3.  If I understand you correctly, you can't go down anywhere near that low.

I tried this today and it turns out that in every browser i cant't distinguish anything lower than about 11 in this test. White seems to be fine where i can see everything up to 254. Changing brightness and/or contrast doesn't change the output of my screen to the positive. I somehow doubt that the screen is broken as it is fairly new but lack any better explanation.

Btw, loading the LuLa barn image into Photoshop gives me the same results as the browsers but curiously embedding an Apple RGB profile seems to get me closer to what I see at home on my Mac.

It seems that my problem is either in a faulty monitor on in some system wide screw-up that clips my shadows.
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Ownaz
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« Reply #6 on: November 19, 2012, 02:58:46 AM »
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Since the Black test on my colleagues identical computer shows the same results (indistinguishable black levels lower than 11) we can probably exclude the faulty screen theory. His screen is working in factory settings btw. and changing the brightness or contrast does not improve the results either.
« Last Edit: November 19, 2012, 03:02:33 AM by Ownaz » Logged
Simon Garrett
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« Reply #7 on: November 19, 2012, 05:09:06 AM »
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Since the Black test on my colleagues identical computer shows the same results (indistinguishable black levels lower than 11) we can probably exclude the faulty screen theory. His screen is working in factory settings btw. and changing the brightness or contrast does not improve the results either.
But yet my LP2475w and Win7 (calibrated with ColorMunki Display at around 90cd/m2) doesn't have this problem.  So it's also not a generic problem with this type of monitor. 
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Tim Lookingbill
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« Reply #8 on: November 19, 2012, 11:19:47 AM »
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The mentioned crushed shadow descriptions on calibrated/profiled displays viewing the Lagom target can get confusing because the custom profile while loaded in the system is suppose to provide LUT curves on start up that would correct the crushed shadows caused by the non-calibrated/profiled native state of the display viewing an image in a non-color managed web browser.

If you're on a Windows system, you don't know the extent these LUT curves are being used to override the display's native state in the shadows. What happens when you switch from the custom profile to loading AdobeRGB (no LUT curves) as the system profile? On restart your display should look a bit darker. Macs can do this on the fly without a restart so it makes this difficult to judge on Windows unless Windows has changed their separate LUT loader on startup routine from the past.

When I choose a LUT-less profile (i.e. AdobeRGB, a 2.2 gamma encoded space) as my system profile in Mac OS 10.6.8, the shadows noticeably but slightly get darker and the highlights get brighter even though both my custom I1Display profile and the AdobeRGB have the same 2.2 gamma encodings. It's the correction to a non-optimal 2.2 gamma of the native state of the display the LUT  curves correct for. This is why calibration/profiling is implemented.

Either Windows is implementing its own appearance of 2.2 gamma shadows through its color management implementation in a non-CM browser or your monitor's native state has a much narrower dynamic range especially in the shadows that the LUTs on their own without CM can't correct for.

You have a mathematically perfect 2.2 gamma curve called the TRC embedded in all profiles (custom & canned) and you have the LUT curves that correct for the display's anomalies that deviate from this perfect state. We don't know the extent those LUTs are correcting the possible deviation in a non-CM browser and whether Windows is doing something with its CM implementation.

Confused? Just FYI, it took me a while to write this as clear as I could.
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Simon Garrett
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« Reply #9 on: November 19, 2012, 01:32:26 PM »
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On Windows 7 you shouldn't have to reboot to force the driver to reload the LUT.  In the control panel "color management" app, simply click on "Reload current calibrations" (in the advanced tab) to reload the current default calibration. 

To the best of my knowledge, Windows doesn't (ever) apply its own TRC.  If there is a monitor profile with an LUT loaded then the driver does it (sometimes the video hardware).  That means that all programs (whether colour managed or not) get the effect of the TRC defined in the LUT (except some games and other programs that bypass driver functions). But the Windows OS doesn't do colour management. 

Windows provides colour management functions for applications that invoke them.  These are provided by WCS ("Windows Color System") in Vista and Windows 7/8, and a more primative "ICM" in XP.  Applications that don't ask don't get colour management (except the TRC and white point, as they're done in the driver). 
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Tim Lookingbill
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« Reply #10 on: November 19, 2012, 04:33:32 PM »
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Simon, thanks for the Windows CM clarification. Good to know the LUT doesn't require a reboot to load in the video card as it did in the past.

I may be misunderstanding the definition of TRC as I thought it was the actual defined gamma curve embedded in the color space as a mathematical definition that CM apps utilize for gamma correct previews evident from the lightening/darkening effect on previews by assigning an image encoded in one gamma a color space with an alternate color space having a different gamma like assigning Colormatch 1.8 gamma profile to an image encoded with 2.2 gamma sRGB.

Other than that how do you explain the non-CM crushed shadows folks report here on what seems high quality displays?
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digitaldog
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« Reply #11 on: November 19, 2012, 05:07:49 PM »
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I may be misunderstanding the definition of TRC as I thought it was the actual defined gamma curve embedded in the color space

You can have a curve that follows the gamma formula which is a TRC. But there are TRC's that are not simple gamma curves.

The reason Adobe calls sRGB's gamma curve Simplified when futzing with the custom colors is it only defines gamma values. The sRGB tone curve is a TRC thanks to that bump down in the shadows. It can't follow the gamma 2.2 simple curve.
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Andrew Rodney
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Tim Lookingbill
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« Reply #12 on: November 19, 2012, 08:16:16 PM »
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Thanks for the TRC clarification, Andrew.

Can a TRC have the bumps and bends that correct for display anomalies for each RGB curve like a LUT?

Or is a TRC just just strictly a one RGB composite luminance curve?
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Tim Lookingbill
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« Reply #13 on: November 19, 2012, 08:23:31 PM »
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Something else odd I noticed about the new HD color spaces that appear in the Assigning and Converting dialog box menu in Photoshop (at least in CS3) is some have VERY different tone distribution characteristics as if they're trying to mimic movie/TV's flatter looking contrast in the shadows when assigning to an sRGB/AdobeRGB encoded image.

You thought sRGB's bump curve was bad. These HD ones are something quite different.

These don't appear in Mac OS Display Preference to choose as a display profile like AdobeRGB and others.
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Ownaz
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« Reply #14 on: November 19, 2012, 09:22:02 PM »
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Thanks again to all for your replies and the lively discussion that ensued, especially the more technical explanations.

I feel like some clarification for my case is needed.

The crushed shadows are a system wide problem on both my PC (CM) and my colleages PC (non-CM), identical setups with the HP LP2475, Win7 and nVidia Quadro FX3800. All my browsers (Firefox, Safari, IE, Chrome) show the same results and I have checked that at least Safari is applying CM. Any dark tones in any application disappear into black, be it shadows in an image in Photoshop or Windows Photo Viewer or just dark lines on a black background in AutoCAD (a problem my colleague is battling).

Since Win7 indeed finally allows for on-the-fly changes of color profiles I have just for the fun of it checked all available profiles and none of them brighten up the shadows in any way. Measuring the display quality with i1Profiler also produces a perfect result according to the software.

What really puzzles me is how even on my colleagues unmanaged PC, so basically at factory settings, the same problem occurs.
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digitaldog
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« Reply #15 on: November 20, 2012, 09:56:04 AM »
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Can a TRC have the bumps and bends that correct for display anomalies for each RGB curve like a LUT?
Or is a TRC just just strictly a one RGB composite luminance curve?

TRC is just a Tone Response Curve which can be simple or complex. So if it follows the gamma curve (gamma formula), it's a simple shape unlike the sRGB TRC. If you're going to be talking about complex curves (anywhere), it is a good idea to use the term TRC and not Gamma. If you're talking about a gamma curve, call it that or use TRC if you wish (or both). Short of seeing the actual curve, the only time I'd think this would be useful would be if you needed to create some kind of modified RGB working space and you were dealing with simplified gamma curves.

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Andrew Rodney
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sandymc
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« Reply #16 on: November 20, 2012, 10:06:48 AM »
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I just tested my LP2475w on the Win7 system that I use to run LR. It uses a I1 calibration profile.

On the http://www.lagom.nl/lcd-test/display_settings.php#color_management site, using Firefox to view, I go from 1 to 254 (barely, but clearly).

I'd be inclined to suggest that the controls on your monitor are out. And btw, I calibrate to 120.

Sandy
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Tim Lookingbill
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« Reply #17 on: November 20, 2012, 01:39:59 PM »
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Just FYI but I drag/dropped the lagom Black test onto my Mac desktop and the file is in .png format. That clued me in the target was created on a Mac.

Opening in Photoshop I get the dialog box indicating it's untagged. I assign my i1Display profile and of course it doesn't look as it does in color managed Safari. I can only distinguish down to level 3 and just a hint at 2.

Another clue it was created on a Mac is that the PS's info palette shows the corresponding RGB readouts as they are numbered for each square with an Idx=Indexed? number added just below the RGB readouts.

Went a step further and opened Mac OS's Digital Colormeter set to 8bit RGB and sure enough the DCM numbers match up to the PS's info palette. Since there's no source space that generated these RGB numbered squares, you can't convert to that space so that you can assign your monitor profile to get the preview to match as it does in CM Safari.


There is only several profiles strangely enough that make the #1 black square appear as bright as it does in Safari by assigning it and they are my canned Epson NX330 Printer/Scanner/Copier profile, HDTV (Rec.709), SDTV (NTSC) and SDTV (PAL) which all have oddball gamma/TRC? curves that don't follow the traditional 2.2/1.8 gamma curve appearance when assigning to images encoded in those spaces.

I wonder if this is why I get such good color matches printing out of Photoshop letting the printer manage the color. Or are the odd shaped curves embedded in these newer color spaces a new standard for color reproduction across print, TV and the web?

Do the "assigning" experiment on your Win systems and see what you get. I have a feeling the reason you're getting such crushed shadows is there may be an internal default type of gamma compensation operating in Win systems that's trying to correct or is engineered into the video card (or your display electronics?) for the TV standard gamma curve similar to what's hardwired into SDTV and my Epson printer color space profiles.

Or it could just be a coincidence.
« Last Edit: November 20, 2012, 01:53:19 PM by tlooknbill » Logged
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