Hardware Profiling a Laptop LCD - Impossible?

Tim,

 

My Sony CRT & MBP LCD were both calibrated with i1.

 

Blue purity (0,0,255) color-managed looks the same as non-color-managed on my Sony CRT.

 

Blue purity on Sony CRT looks darker and a bit more 'blue' (for lack of better words!) than blue purity in non-CM app on my MBP LCD.

 

So i1 profile on MBP LCD is trying to compensate... by adding reds! Looking at Eugene's description on the 3D PCS plot, this behavior makes sense in terms of the manner in which the color-management module is working.

 

But is it optimal for what I want to see? In the blues, certainly not. You may be right; there may be some strange way in which the i1 colorimeter/software is working with my MBP LCD... but I don't even know how to begin to tackle this problem.

 

However, you're right, it would be interesting to see how RGBCMY purity gradients look in nonCM apps on my MBP LCD vs color-managed on my CRT (since I think that the i1 did a good job with my Sony CRT)... did I get you right in the experiment you were proposing?

 

Perhaps this weekend after finals I will give that a shot and post my results.

 

Cheers,

Rishi

Just one slight difference in the experiment. The purity gradients

need to be examined in a nonCM app on both display's.

</p>

 

<p>

What you want to get the two displays to show is what

response/appearance the i1 colormeter is measuring from. To

go even further it would be even better to examine these purities

at the point the i1 Match software clears the vLUTs which usually

has the appearance of the screen becoming slightly darker.

</p>

 

<p>

The issue with doing that though is it requires both displays to

be loaded in i1 Match at the section where the LUTs clear. There

is a workaround using an app called Profile Gamma Tagger

which allows the embedding of a ramped shaped=(without a

gamma curve) response to any display profile, custom or

canned.

</p>

 

<p>

You can download it from here:<a

href="http://www.chromix.com/ColorSmarts/noteSearchResults.c

xsa?resourcetype=utility&-session=tx:0CA2913607b132BFB8IXJ

1F25432">Chromix ColorSmarts</a>

</p>

 

<p>

Pick "Linear" when it prompts you with the dropdown menu

selection.

I have a gradient chart made in Apple's sRGB that would clearly

show the differences within the two displays because it's

posterized to show 8 steps, but you can make your own if you

wish.

Sorry,

 

Something else comes to mind that might have an influence on

calibration I started noticing with cheap CRT's picked up at thrift

stores. During a calibration session when the colormeter is

measuring the color patches I noticed how fast some colors go

to black and other colors, especially greens and blues leave a

latent image or at least a fade effect compared to other color

patches.

 

I was told by a color expert years ago when assessing the quality

of any CRT that some may have varying rise and fall refresh

speeds along with what they call short and medium persistance

green phosphors that can affect colormeter measurements as

well as judging raster patterns using eyeball calibrators. This

was to warn me in whether I bought the expensive Barco or my

cheap $600 Princeton EO90.

 

Since this is an LCD using a completely different technology to

emulate CRT's P22 phosphor response and may be doing it

badly, it might be the issue here.

I have same problem (almost the exact same color shift) using a Monaco colorimeter and a Flexview (IPS) laptop screen (Lenovo T60). I had this problem with my old laptop (HP w/ WUXGA screen) and was hoping the change to an IPS screen would fix it.

I've read on the web IPS screens are only made in 19" and above

sizes. I've never heard of a laptop with an IPS screen.

 

My 2000 Pismo which must have a TN panel has the same

purplish blue using the EyeOne Display profile. Switching to the

canned G3 Powerbook series profile corrects it but now all the

other colors especially fleshtones are off.

 

I believe the EyeOne software is trying to bend the scrawny

gamut of laptops to allow accurate representation of a majority of

colors at the sacrifice of a few.

Yes, I believe Tim's right.

 

I've tried all different software packages with my i1 colorimeter on my MBP LCD screen.

 

Fleshtones and warm colors have been corrected due to profiling, as well as detail in shadows. However, blues turn purple. I guess that's a sacrifice I'm willing to make for the accuracy of other colors.

 

I even tried 16-bit LUT display profiles, which actually helped render smooth tonal gradients with minimal posterization on my laptop screen. Still, blues turned purple.

 

This is probably an issue that the software companies for the colorimeters would have to take up, if they give a crap about their products properly profiling laptop LCDs. They could probably add a tweak in the software to stop this behavior with blues.

 

But who knows if it's worth it to them.

 

Thanks for everyone's help. This was quite a long-winded and enlightening discussion thread.

Cheers,

Rishi

<p>Just a thought... not seen it mentioned in this thread, so i though i might share my

findings.<p>

 

<p>I too had the blue showing as purple issue, on my recently purchased 20" Cinema

Display attached to my 17" Intel iMac.<p>

 

<p>The default save location for ColorSync Profiles in the OS X is:</p>

 

<p>/Library/ColorSync/Profiles/Displays/</p>

 

<p>I used SuperCal to make a new profile this default location was</p>

 

<p>~/Library/ColorSync/Profiles/</p>

 

<p>This was when i started noticing the blues being purple.</p>

 

<p>It was most odd as it was appearing in some places and not others, name the OS X

colour picker app:</p>

 

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/5774751-lg.jpg" /></p>

 

<p>I ve had a bit of experience with Tiger being funny about permissions, so i thought it

might be a permissions thing? some CM apps needed the right permissions to access the

profile, if it was in the users library then they might not be able to access it?</p>

 

<p>Anyway so I moved my calibrated profile to:</p>

 

<p>/System/Library/ColorSync/Profiles/</p>

 

<p>and hey presto blue, lovely blue.</p>

 

<p>This might sound to simple but it worked for me! I hope it can help someone

else..</p>

 

<p>Thanks, Henry</p>

I don't understand how this would help.

 

I *know* that Photoshop is using my i1-generated calibrated profile, yet it gives me purples instead of blues.

 

Actually, re-reading your post, I'm sorry, I just can't make any sense of it. If you'd like, please clarify.

 

Thanks,

Rishi

I just sampled your 255 blue in a nonCM browser using Apple

Digital Color Meter and your blue looks correct but its RGB mix is

76,34,255 which is basically a luminance difference between

your SuperCal adjusted vLUT captured in the screenshot and

how it reads straight off my frame buffer in OS 9.2.2.

 

I started experimenting to see how much adjustment it would

take to see a difference in 255 blue created in an AdobeRGB doc

in Photoshop using PS's color picker and it seems you can add

quite a bit of the red but not as much as the green until a

difference can be seen.

Hello, sorry, im not very good at explaining myself!

 

Im not sure whether we were having the same problem.

 

Bascially I have put the calibrated profiles in:

 

/System/Library/ColorSync/Profiles/

 

and deleted them from other locations, then relaunched System Prefs and reselected them.

 

this made the system & CM apps show the correct blue for me.

 

If i put them back, they go purple again.

 

Ive have now used a i1 myself to calibrate 2 profiles for each monitor, which has helped no

end to get similar colours on both screens, which is the idea i suppose. :O)

 

does this help you at at?

Henry, are you sure that your profiles are getting loaded from the new location? It is hard to believe the software cares where it is loaded from.

Just recently getting to know OS 10.3.9. Everything I've read

agrees with what Henry states, but only in regards to how the OS

accesses ICC profiles. I can put profiles in a number of

Library/Colorsync/Profiles locations-System or Administrator.

Apple's Colorysync Utility will show them all in the list.

 

It doesn't say anything about Photoshop being able to though.

But how does this have *anything* to do with blues turning purple? We've already confirmed (I think) here that that it's the *calibrated* profiles that turn blues to purple...

 

Plus, I *know* that Photoshop is accessing my profile because under 'Color Settings', in the drop down menu for RGB Working Space, Photoshop shows me: Monitor Profile - LaptopLCD_i1_D65_2.2-LUT, which is my i1 calibrated profile...

 

Tim, I have yet to look at some RGBCMY purity charts. I was swamped with finals and had left this discussion aside, understandably, as it required too much brain bandwidth (well, at least, along with everything else). Also, your post about CRT phosphors and problems/interactions with colorimeters is interesting. I would have to check next time I calibrate whether or not some colors go to black quickly during the profiling process. At any rate, I don't claim to understand the technicalities of it nor why it would be affecting just the blues.

 

Finally, interesting that you can increase brightness of blue by adding green and getting less subjective 'hue shift' compared to increasing brightness by adding red. But, according to how the compensation for out-of-gamut colors occurs in LAB (i.e. maintaining the hue angle), as Eugene Scherba has graciously shown in a previous post, blues necessarily take on a purple hue given the particular shapes of the sRGB vs. monitor color profiles in question here.

 

Now I wonder if fooling with the LCD brightness when calibrating will change the behavior of blues or not. For example, what if I calibrate with my laptop set to full brightness?

 

Guess I'll have to try :) Will let you know the results...

 

-Rishi

L G, Mar 31, 2007; 09:59 a.m.

"Henry, are you sure that your profiles are getting loaded from the new location? It is hard

to believe the software cares where it is loaded from."

 

The profiles only exist in one place, ive deleted them from all other locations. OS X is

heavily reliant on permissions, applications cannot access files unless they have the

correct permission. This must apply to the CM system apps.

 

Rishi Sanyal, Mar 31, 2007; 06:56 p.m.

"But how does this have *anything* to do with blues turning purple?"

 

My blues turn purple unless the profiles are in the right place?

 

"Now I wonder if fooling with the LCD brightness when calibrating will change the behavior

of blues or not. For example, what if I calibrate with my laptop set to full brightness?"

 

Have you had any luck with this?

Thanks for reminding me Henry... I completely forgot to try!

 

Please come back and remind me again if I haven't tried this over this weekend. I'm losing my mind these days over school work... :)

 

Cheers,

Rishi

-- Thanks for reminding me Henry... I completely forgot to try!

 

Any luck still?

Thanks for reminding me again... still haven't had a chance to try... however, perhaps part of the problem lies in what is outlined in this lawsuit against Apple...?

 

http://www.appleinsider.com/articles/07/05/18/apple_hit_with_class_action_suit_over_macbook_macbook_pro_displays.html

 

-Rishi

Rishi,

 

Now look what you've done and you dragged me in on this to

boot. Soon we'll both be called as witnesses. Dang! There goes

my summer vacation.

 

Kidding aside, I can't understand what the big deal is about

having a laptop display or any display for that matter be perfect. A

commercial press for which the majority of pro color work is

targeted vary's so much color accuracy can only be used as a

guide. I'ld like to see how they're going to prove this.

 

Interesting link. I wonder if it's just a rumor, though.

Hey! For the record, I have nothing to do with that lawsuit :)

 

I've been sensible enough to get a CRT & a 2005FPW to do my photo editing work...!

 

Cheers,

Rishi

Just found and read through this thread—I'm seeing the same thing with a ColorVision Spyder 2 that I used to calibrate my

display. Did anyone find a solution, or is it just a hardware limitation? I only calibrated my display to make it look better, not

so much for color accuracy; is it possible to get CM apps like Safari to ignore the hue shift?

Nope, never found a solution. I chalked it up to some strange manner in which the profiling devices interact with the laptop LCD & whatever jacked up algorithm they use for expanding the apparent color gamut. Perhaps this leads to the profiling package 'seeing' a blue primary for the laptop LCD that is very different from any 'standard' blue primary (pretty far off from sRGB's blue primary, as is evidenced above). Then, in correcting it, it mucks everything up.

 

You know, what'd be interesting would be if someone tried this on a laptop that is NOT a Mac. Kevin, what's your laptop?

 

I just received an email from another guy who has a Mac that says he has the same problem. I wonder if it's a Mac specific thing.

 

Someone please try on a non-Mac laptop. I may also when I have a free moment :)

 

Rishi

I have a MacBook Pro, so I'm afraid I can't help there. I have seen reports of it happening to an HP laptop by searching Google, though. So

maybe it is just a laptop thing. Seems like they'd fix that, though.

 

Out of curiosity, do you end up using the canned profile or your calibration on the laptop display?

I end up using the profile generated by i1 because for most other colors/saturation, etc., it works better. I.E. I get colors looking more like my Dell 2005FPW and pics uploaded to the internet look reasonable on other, uncalibrated monitors. I don't mess with blues when I edit my images on my MBP LCD, though, b/c I know my edits would/may be totally off.

I have the same problem (blue turning to purple) with my HP 6910p (Vista 64) and the i1 display 2 (tried with 2

calibrating apps: i1 Match and a demo version of ColorEyes Display Pro).

 

And I also have the same problem with my "external" LCD (20'' MVA panel).