Discrepancy between calibrated screens

[luong]

My main screen is a Sony Artisan (CRT), used with a G5. I have also a Dell 2405 (LCD) with a macbook. In an effort to match them, I use the same software and hardware to calibrate them, Coloreyes Display with the Coloreyes/Xrite DTP94.
Settings on the Artisan: CRT,DDC,D65,L*,110cd/m2
Settings on the Dell: LCD, D65,L*,110cd/m2

When using Coloreyes, both profiles validate with an excellent maximum DE of about 1.

Yet, visually, the shadows on the Dell appear much brighter than on the Artisan. I can often see shadow detail on the Dell, when on the Artisan they are quite black. Is it a normal consequence of comparing two screens of different types ?

I have also an older KDS (CRT) that I use as a secondary monitor on the G5, and although it doesn't validate as well (maximum DE 2.3), it matches the Artisan more than the Dell when it comes to shadow detail.

Not surprisingly, I trust the Artisan more, and it does provides a relatively good match with my Epson 9800 prints. However, I find that curious that the Dell apparently calibrates well, but then provides blacks that are appear so different. Is there an explanation ?

[pfigen]

For one thing, you're comparing apples to oranges. LCDs and CRTs are very different technologies. Remember that CRTs are designed to run at lower overall luminence and have much blacker blacks overall. What are you setting for a black point in the calibration software? If it doesn't let you spec that, then it's not what you want or need. Remember that one of the best features of the Artisan software and puck was that you could spec black point level and know it was going to be accurate. So, what you're likely seeing is the Artisan running brighter than it really wants to (85-90 cd/m2) and probably running a "normal" black of around .3 cd/m2 while your LCD is running lower than it wants to at 110 cd/m2 on the white but most likely something like .6 on the black. It simply can't match the black of the CRT and shouldn't. I'd go back to the Artisan software and hardware and know that it's your reference and make everything else as close as you can.

[Hermie]

Didn't know the Artisan could go that far :-) Why are you not using the original Sony software, doesn't it calibrate anymore (loop)?

I remember this post from Ethan Hansen on another forum:
"Some CRT displays can go over 100cd/m^2 luminance -- just not for long. Bright levels quickly burn out the tube. Values in the 85-95 range provide a reasonable compromise between display lifetime, color gamut, and contrast range. They do, however, require working in a dimly lit room.

Backlights on LCD screens are not subject to such limitations. An LCD can hum along at CRT-cooking luminance levels with no worries. In fact, they require it to get the most out of the display. Obtaining a decent color and contrast range from a typical LCD takes setting the screen output to at least 120 cd/m^2. This creates a problem of another sort. A display blasting out 120-140 cd/m^2 is uncomfortably bright in the darkened cave good CRT editing require. Using both types of monitor simultaneously just does not work well for extended periods. We ended up with LCD and CRT monitors in different rooms for this reason."

[luong]

Thank you for the reply. I normally run the Artisan at 90 cd/m2, but I thought that running it brighter would make the shadows brigher and therefore closer to the LCD. The Sony software and hardware work fine, but Coloreyes makes it easier to calibrate a dual display, and I was also hoping to get a better match with the LCD by using the same software.

I agree with the Artisan running a bit bright and the Dell a bit dark, but why wouldn't that cause the shadows to be brighter on the Artisan than on the Dell, rather than the opposite ? The older version of  ColorEyes display that I have doesn't allow to set a black point luminance. I see that the newer one does.

[pfigen]

"but why wouldn't that cause the shadows to be brighter on the Artisan than on the Dell, rather than the opposite "

Because, unlike the LCD, the CRT can have the black and white points adjusted independently. On the LCD, because there is only one real control, everything slides up and down more or less in sync. The CRT is much more dynamic in its control.

[luong]

I am not sure I understand "everything slides up and down". If that would be the case, then wouldn't the black point go down when I lower the white point on the LCD ?

On the other hand, I can see that if the black point stays the same (because the LCD is unable to do darker blacks), while the white point goes down, then the shadows would be brighter relative to the rest of the luminance range than when the monitor had a brighter white point.  On the other hand, with the CRT, when I crank up the white point, the black point remains low and therefore shadows look darker.  Is that correct ?

If that's the case, would it mean that I would get a better overall match (same highlight to shadow relationship in both screens) if I run the CRT dimmer and the LCD brighter and adjust perception for the global difference of luminance levels, rather than trying to set the same white point ?

[pfigen]

"I am not sure I understand "everything slides up and down". If that would be the case, then wouldn't the black point go down when I lower the white point on the LCD ?"

Yes, I should have been more clear. There is a floor below which the LCD will not get any blacker.

"On the other hand, I can see that if the black point stays the same (because the LCD is unable to do darker blacks), while the white point goes down, then the shadows would be brighter relative to the rest of the luminance range than when the monitor had a brighter white point. On the other hand, with the CRT, when I crank up the white point, the black point remains low and therefore shadows look darker. Is that correct ?"

Again, yes. There are limits, but yes.

"If that's the case, would it mean that I would get a better overall match (same highlight to shadow relationship in both screens) if I run the CRT dimmer and the LCD brighter and adjust perception for the global difference of luminance levels, rather than trying to set the same white point ?"

Ideally you would run both in different environments, calibrated to their optimum settings and varying the ambient light to match perception.

[luong]

Thank you for the clarification. Before attempting to match luminance on the screens, I said to my wife that she should  wear sunglasses when working on the LCD since in general I kept the room quite dark :-)

[Tim Lookingbill]

luong,

I have the same issue as you on my first quality LCD, a 2004 model 20" G5 iMac. It's black point viewed when the i1 puck is measuring it looks dark blueviolet. It's so bright though I can't see it in normal use.

I tried reducing the brightness adjusting the backlight brightness slider within Display Preferences, but all it does is provide a flatter appearing brightness much like lowering the contrast. The 20-60RGB gray shadow section does get darker but with a much flatter response where a CRT's is more graduated. The shadow roll off into black point on the iMac just won't match the roll off characteristics of my CRT which has a separate contrast adjust-(controls brightness of white) and brightness adjust-(controls brightness of black point).

I have both calibrated to a luminance of around 100cd/m2 to match my ambient viewing light.

[neil snape]

luong,

I have the same issue as you on my first quality LCD, a 2004 model 20" G5 iMac. It's black point viewed when the i1 puck is measuring it looks dark blueviolet. It's so bright though I can't see it in normal use.

I tried reducing the brightness adjusting the backlight brightness slider within Display Preferences, but all it does is provide a flatter appearing brightness much like lowering the contrast. The 20-60RGB gray shadow section does get darker but with a much flatter response where a CRT's is more graduated. The shadow roll off into black point on the iMac just won't match the roll off characteristics of my CRT which has a separate contrast adjust-(controls brightness of white) and brightness adjust-(controls brightness of black point).

I have both calibrated to a luminance of around 100cd/m2 to match my ambient viewing light.
[a href=\"index.php?act=findpost&pid=165267\"][{POST_SNAPBACK}][/a]

Just a few notes.
The
LCD has a polarized light by nature both the crystal and the micro lens add to this. You will always see a different view of your screen than the nominalized puck will.
The delta E differences will always be more subtle in the shadows. A difference in the white max output will have more room for perceived differences, whereas you will always see differences between the absolute black rendering, as Peter said.
The LUT's for the LCD will not have the accuracy to have a lot of smoothing in the shadows hence a boost in the shadows is probably desirable for transitions. The photon counting (software controlled) may be a resolution problem hinting at  an advantage in the Artisan as there are no requirements for high bit LUT's for screen correction.
Recently screen makers are asking for custom colorimeters with filters and software adjustments that optimise the device/software combo for specific screen technologies.

I have not yet seen a perfect LCD to CRT match, yet the Artisan is a good reference as a start point, especially with CE.

[Tim Lookingbill]

I've read some of the newer NEC's are requiring custom filter colorimeters combined with their own software to get optimum results, so I imagine there will be other manufacturers doing the same.

I suspect my iMac needs a better colorimeter as well. The brightness of my iMac tends to make the i1 Display overshoot gamut size when creating the profile to where saturation of color managed previews are slightly reduced compared to the CRT. However it might be more attributed to the luminance distribution differences or maybe both.

And the colorimeter really can't see shadows that accuately either because, despite the blueviolet black point, the final i1Match RGB TRC graph shows no attempt to correct for it. On the Samsung CRT, however, there is a pronounced reddish cast in the blacks and shadows when the LUT's are cleared and the final graph shows i1Match correcting for it by applying RGB tweaks farther down closer to black point compared to the iMac.

I know when using Apple's eyeball calibrator the black point is locked down no matter how high I raise the raster target sliders and brightness slider in Display Preferences.

Not comparing them to CRT's I'm starting to prefer the LCD instead for their better border to border uniformity in luminance, white point and color purity. Not having to degauss like I occasionally have to do on the CRT is another plus.

[jackbingham]

Ok, lets stop wandering around and get to the meat of the matter. I assume that the user chose relative black in Coloreyes under Black Point target. That means that ColorEyes will set zero based on the actual measurements from each screen. As it measures downward from white it will test at what point the measurements no longer change. So it measures 5 r g and b and sees a change from the measurement above but then measures 4 r g a b and sees no change. Coloreyes then sets zero at 5 rgb and scales everything upward. Now since these two displays behave very differently that could easily make them display black differently. If a critical black match is required you could do one of two things. You can target the same black value on both monitors assuming you pick a value they can both hit. The second thing you could try is absolute black. That sets zero to zero. Now you may find that doesn't work for you because one of the monitors will have plugged blacks. One of life's little compromises.

[digitaldog]

I've read some of the newer NEC's are requiring custom filter colorimeters combined with their own software to get optimum results, so I imagine there will be other manufacturers doing the same.

Just the LED from NEC (they ship a tuned colorimeter for that unit). In theory, this could be done with most Colorimeters off the shelf with software, its a tweak to some matrix settings inside the unit. Expect for very wide gamut devices, you'll be fine. On my NEC 2690 ("93%" of Adobe RGB (1998) and in quotes for good reason), the differences between the white point measured with an EyeOne Display and Spectrophotometer were a mere 500K. You're better off using the Colorimeter although if you have both devices, there's a way in the NEC software to use them if that 500K bothers you.

Getting back to the Artisan, I see Karl Lang has updated a new patch for that unit (mine still runs fine even under Leopard). Its at http://www.lumita.com/labs/artisan/

He also has a new article that discusses this so called accuracy issue based on reference grade devices that's short and a good read. It provides insight in how silly it is to use the same device to calibrate a display and expect its going to tell you something about the so called accuracy of the calibration (something discussed here in the past). You'll find out why a $20K-$100K Spectroradiometer is the tool to use if you really have the time and money to wonder about accuracy.

http://www.lumita.com/site_media/work/whit...-3-comments.pdf

[Hermie]

>  Getting back to the Artisan, I see Karl Lang has updated a new patch for that unit

Also for Windows now! Quote from Karl's website:
"Limited testing has been done under Windows XP (SP2). The new “calibrate” seems to work properly."

Question:
Has anyone been able to run the Sony Artisan software on Windows Vista. I've just sold my unit and buyer runs Vista.

> He also has a new article ...

I've noticed that PDF. According to the document properties, it's from May 2005.
It looks like a concept; it includes review notes.

Herman