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Author Topic: Why do I need wide gamut monitor  (Read 9252 times)
tony field
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« on: November 13, 2008, 12:28:36 AM »
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Do I need a wide gamut monitor such as the HP LP4275w for photography?

I purchased Gamutvision to look at printer profiles.  

http://www.gamutvision.com/docs/tour_gamutvision.html

One of the things I noticed is that my Epson 4800 print gamut is smaller than even sRGB.  This is demonstrated in the image below - generated by Gamutvision and Epson provided profiles.

If that is the case, then why is it useful to have a wide gamut monitor? It is unnecessary, obviously, for web image generation.  It also seems to be unnecessary for photo printing.  Why get the HP LP2475w with a gamut even wider than Adobe RGB?  Are there any benefits for the editing process?

sRGB comparison


Adobe RGB comparision


tony
http://www.tphoto.ca
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Paul Holman
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« Reply #1 on: November 13, 2008, 01:21:40 AM »
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I'm not sure you're seeing useful information comparing those profiles*.

The gamut plot of the printer suspiciously follows the volume of sRGB too closely. I'd suspect that the target used to build the profile concerned had been converted to sRGB before printing the profiling targets to restrict the gamut to sRGB (not necessarily deliberately, it may just be an error).

Almost every inkjet printer can print beyond sRGB if correctly profiled, if only for a few parts of it's gamut.
Certainly all the 3800 and 4800s I've profiled all have larger gamut volumes than sRGB when used with decent paper. Many have gamuts that extend beyond Adobe RGB in parts too, hence why many people want wide gamut monitors.

*Also worth noting that 2D graphs only show a single slice through the gamut volume that doesn't reveal all the information you need. 3D plots tell more of the story, although they can be difficult to display on the web effectively.

Paul @
www.colourprofiles.com

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Wayne Fox
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« Reply #2 on: November 13, 2008, 03:04:04 AM »
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I would agree with Paul.  In fact, I believe the 4800 even exceeds aRGB in a small area on some papers.

Trying to think of a good way to express why I think the wider gamut monitor is better .. I'm about to buy one myself.

It's not about matching gamuts from input to output devices ... it's about management the visual relationships of what we see.  A file normally starts off having colors that exceed AdobeRGB, but the color management system does a very good job of allowing two different devices with smaller gamuts to appear somewhat similar to each other, so we can use one device to effectively achieve a desired result on another device.  Having a better monitor improves on that.  

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mbalensiefer
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« Reply #3 on: November 13, 2008, 04:16:41 AM »
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Wayne, what monitor and profiling device are you using successfully?

Thank you!
Michael
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edwinb
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« Reply #4 on: November 13, 2008, 04:21:28 AM »
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Quote from: tony field
If that is the case, then why is it useful to have a wide gamut monitor?


if you can see the colour information you can make an informed decision about what your printer will output.
if you had a monitor only showing the printer gamut your file would be showing you only the data remaining after the conversion and maybe you would have chosen a different conversion if you had seen the original data.
ideally you would have a monitor that excedded the gamut of your camera.
edwin
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digitaldog
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« Reply #5 on: November 13, 2008, 08:11:04 AM »
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Quote from: tony field
Do I need a wide gamut monitor such as the HP LP4275w for photography?

I purchased Gamutvision to look at printer profiles.  

One of the things I noticed is that my Epson 4800 print gamut is smaller than even sRGB.  This is demonstrated in the image below - generated by Gamutvision and Epson provided profiles.

It (your display) most certainly isn't larger. That Gamut Viewer thinggie is only showing you a 2D map. You need to look at the gamut in 3D and view the entire area. You'll see that K3 inks exceed
Adobe RGB (1998) in some colors and is way larger than display gamut of sRGB!
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Andrew Rodney
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tony field
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« Reply #6 on: November 13, 2008, 11:14:12 AM »
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Quote from: Paul Holman
The gamut plot of the printer suspiciously follows the volume of sRGB too closely. I'd suspect that the target used to build the profile concerned had been converted to sRGB before printing the profiling targets to restrict the gamut to sRGB (not necessarily deliberately, it may just be an error).
The output from Gamutvision has the dotted outline is the sRGB gamut space.  The solid line is the printer gamut.  Clearly, the printer space is smaller than sRGB.  The actual printer profile is generated by Epson using a i1 for the Premium Glossy Photo Paper (250) - Epson profile file "SP4800 PGPP250 PK 2800.icc".  I doubt Epson made errors when generating this file.

If the epson profile "Pro4800 PGPP250.icm" is displayed with Gamutvision, it has a different gamut but mostly is smaller than sRGB.

Quote
Almost every inkjet printer can print beyond sRGB if correctly profiled, if only for a few parts of it's gamut.
Certainly all the 3800 and 4800s I've profiled all have larger gamut volumes than sRGB when used with decent paper. Many have gamuts that extend beyond Adobe RGB in parts too, hence why many people want wide gamut monitors.
That is interesting.  In general, everyone says that the printer gamut is larger than sRGB.  Gamutvision seems to indicate otherwise.  It would be very interesting to run your generated profiles with this programme to see how large the gamut space is.  You can download a trial version of Gamutvision and take a a peak.  Alternatively, maybe you could email a sample of one of your 4800 profiles and I can return the plots.

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*Also worth noting that 2D graphs only show a single slice through the gamut volume that doesn't reveal all the information you need. 3D plots tell more of the story, although they can be difficult to display on the web effectively.
As far as I can figure out, the 2D graph plots essentially all of the information of the 3D plot.  The 3D just gives a different representation with colour displayed in a volumetric sense.
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tony field
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« Reply #7 on: November 13, 2008, 11:51:07 AM »
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Quote from: digitaldog
It (your display) most certainly isn't larger.
The HP LP2475w display exceeds the Adobe RGB gamut and has 94% of the NTSC coverage.  See:

http://www.prad.de/en/monitore/review/2008...w-part9.html#3D

Quote
That Gamut Viewer thinggie is only showing you a 2D map. You need to look at the gamut in 3D and view the entire area. You'll see that K3 inks exceed
Adobe RGB (1998) in some colors and is way larger than display gamut of sRGB!
The image below is the 3D display from the Epson 4800 icc file for premium glossy photo paper (250) - and certainly is characterized for K3 inks. Dashed lines indicate the sRGB space, the solid volumetric is the Epson paper space.  As you indicated in the early chapters of your book (pg 22), the 2D representation is simply a clever way of presenting the same information as the 3D plot.

I assume that the Gamut "thinggie" is correct in it's presentation.  I also assume that Epson is following good practices when they created their ICC profiles with the i1 (in particular, their file "SP4800 PGPP250 PK 2880.icc", which I am using for this discussion).  If these assumptions are correct, then is seems that the gamut of the K3 inks on the premium glossy photo paper is smaller than sRGB.

Since the general wisdom is that the K3 inks have a gamut that exceeds sRGB, I am trying to find out how this "ICC profile thing" really works.  My (inexperienced) analysis seems to say that things don't really jive.

« Last Edit: November 13, 2008, 12:00:36 PM by tony field » Logged
digitaldog
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« Reply #8 on: November 13, 2008, 12:08:01 PM »
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There's either something really screwed up with your profile or your gamut viewer. There's no question that the K3 inks exceed sRGB and even Adobe RGB with some colors. My gamut viewer (ColorThink) clearly shows this in a big, big way. Wireframe is sRGB, colors (that huge amount falling outside the wireframe) is Premium Glossy.
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Andrew Rodney
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tony field
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« Reply #9 on: November 13, 2008, 12:11:45 PM »
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Hi Andrew,

Would it be possible for you to email me (tony@shaw.ca) the actual ICC file you used so I can try to duplicate the volumetric display on my software??  At least that would eliminate one variable.
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digitaldog
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« Reply #10 on: November 13, 2008, 12:12:27 PM »
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Quote from: tony field
The HP LP2475w display exceeds the Adobe RGB gamut and has 94% of the NTSC coverage.  See:


FYI, these spec's are pretty meaningless and should go away. NEC is trying:

Quote
I'd just like to add a couple of comments since I'm starting to see more and more confusion related to this issue now that people are doing more software based desktop video editing:

You are very correct that in a traditional video-to-video workflow, "color management" isn't normally necessary, since it can be assumed that each piece of equipment in the workflow knows is working in a standard color video workspace. There are some minor color conversions done such as when transcoding NTSC<>PAL/SECAM due to the slightly different color primaries of each standard.

However that starts to fall apart when people start to use standard desktop computer monitors and laptop displays for previewing output on the desktop, instead of using a dedicated external broadcast standard preview monitor. Most laptop displays have very small color gamuts (much smaller than sRGB), and desktop computer monitors have increasingly larger color gamuts as the technology improves and prices drop.

To make things worse, there exists a lot of confusion in the industry about color gamuts and their relationship to broadcast video, specifically NTSC. With the push for ever larger display gamuts, marketing folks have started to list display color gamuts as a % size or % coverage of NTSC for comparison purposes. Unfortunately this practice leads some to believe that a monitor with a % value closer to 100% *must* be better for use with NTSC video.

In reality this is of course not true because the color gamut used for modern day NTSC video has nothing to do with the original "NTSC 1953" spec, which actually had a very large (and unachievable with the display technology at the time) color gamut - even larger than Adobe RGB. It is however the NTSC 1953 spec that often gets quoted in marketing materials.

For previewing NTSC video on a display monitor without any display color management by the host application/OS, it would be much better to use a standard sRGB display rather than one with a larger or smaller color gamut, since the primaries for sRGB are the same as HDTV primaries and are very close to SMPTE-C primaries used in NTSC video.

It's interesting to see all of the "wide gamut" consumer TVs that are starting to show up in the marketplace due to the increased use of LED backlights and improved color filters and phosphors. While they may look brilliant in terms of amazing color gamut, technically they are producing images that are out of spec in relation to the intended output gamut. I suspect though that the average consumer probably doesn't care and actually prefers the resulting super-saturated images they produce.

Getting back to Ray's original question though, I am not aware if Final Cut Pro or other video editing applications are capable of honoring the display's ICC profile when previewing video on the desktop in order to correctly render color corrected motion video to the screen. My suggestion would be to calibrate the display to be as close to HDTV/sRGB as possible (D65 white point, etc.). Ideally a dedicated external professional broadcast grade preview monitor would be used for final output confirmation.

As an aside: In order to try and reduce the confusion of display color gamuts and their relationship to NTSC, NEC typically lists the display gamut as a % size and % coverage of both Adobe RGB and NTSC 1953 in marketing materials, along with a disclaimer explaining the use of the NTSC 1953 spec. Ideally the NTSC comparison would go away, but unfortunately it has become a display industry standard benchmark.

Best regards

Will Hollingworth
NEC Display Solutions



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Andrew Rodney
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tony field
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« Reply #11 on: November 13, 2008, 02:01:40 PM »
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Quote from: digitaldog
FYI, these spec's are pretty meaningless and should go away. NEC is trying:
Nec's letter is quite interesting.   Thanks for the info.

However, would you (in general) recommend a wide gamut monitor like the HP for photographic editing?

P.S.  I am trying to resolve the apparent differences between the Color Think representation and Gamutvision (wish software was more predictable :-)
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digitaldog
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« Reply #12 on: November 13, 2008, 02:33:54 PM »
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If you're working with imagery outside of sRGB I'd say having a wide gamut display is quite useful.
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Andrew Rodney
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tony field
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« Reply #13 on: November 13, 2008, 02:45:04 PM »
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I just chatted with Norman Koren, the author of Gamutview.  After reviewing this thread, he suggested that I had mis-used the "rendering intent" and should use the intent of "NONE".  Of course, this became obvious and the only correct way to illustrate the absolute comparison between the RGB and printing intent :-)  too bad I did not have the little grey cells in operation when I first posted.  This is really operator incompetence - not just operator error.   It also becomes obvious what the rendering intent does to the display.  This little programme taught me a lot in the past 18 hours....

Here are the corrected samples for the printer comparison.  Obviously, the printers have a larger gamut than sRGB and even, in areas, aRGB.  Now I can take Andrew's guidance and think that the wide gamut monitors are definitely of use.

relative to sRGB


relative to Adobe RGB
« Last Edit: November 13, 2008, 02:46:48 PM by tony field » Logged
GerardK
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« Reply #14 on: November 14, 2008, 02:25:00 AM »
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Tony,

This is a plot of a profile for HP Premium Plus Photo Satin (solid gamut) to AdobeRGB(1998) (wireframe gamut):

[attachment=9691:A1998_to_Satin.JPG]

and this is a plot of the Satin gamut (solid) to sRGB (wireframe):

[attachment=9690:sRGB_to_Satin.JPG]

This is a plot of the gamut for Satin (solid) to the HP LP2475W monitor (wireframe):

[attachment=9692:hp2475w_to_Satin.JPG]

If you compare these two, you can conclude that this monitor gamut covers much more of this printer/paper-gamut than sRGB does. In theory, this should enable you to do a more accurate softproof.

As it is, I'm still having some issues with this monitor that I'm discussing with HP at the moment. I'll update if and when this is resolved.


Gerard Kingma
www.kingma.nu
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tony field
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« Reply #15 on: November 14, 2008, 10:10:45 AM »
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Quote from: GerardK
As it is, I'm still having some issues with this monitor that I'm discussing with HP at the moment. I'll update if and when this is resolved.
I have just ordered the HP2475w.  It should be here within a week.  What issues have you discovered?
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GerardK
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« Reply #16 on: November 14, 2008, 01:55:13 PM »
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Quote from: tony field
I have just ordered the HP2475w.  It should be here within a week.  What issues have you discovered?


I don't want to scare you, I hope I have a faulty unit and yours will be fine - mine will be replaced Monday, I'll keep you posted.

My first unit had a faulty DVI connection, an unstable HDMI connection and the system rebooted every time the resolution changed for instance for playing a game, although that may be caused by the graphics board, I'm not sure. But the real deal breaker was that the screen isn't uniform in colour. If you display a full white screen, it is noticably more red to the right side than in the centre. If you display two identical black-and-white pictures in Photoshop next to each other, the one on the right looks warmer than the one on the left, which makes it impossible to do subtle sepia toning with any degree of accuracy. I discussed this with another forum member in a private e-mail conversation, he noticed it as well in his unit, but it went away when he did a second calibration at 6500K. I calibrated with an Eye-One Display2 at 5000K and at 6500K, but in both cases the hue shift remained. If the second unit shows the same hue shift, I will get a different monitor alltogether. I hope the next one's OK, because it is otherwise a terrific screen, particularly for the price.

And it surprises me, I read the reviews over at tftcentral and prad.de, and they specifically measured screen uniformity and noticed a slight unevenness in brightness, which I could live with, but they did not notice any hue shift, so their test units may have been OK. The inputs are now fairly stable, I could live with that, but I can't live with the colour shift. Good luck with your unit,


Gerard Kingma
www.kingma.nu
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GerardK
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« Reply #17 on: November 17, 2008, 02:42:08 PM »
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UPDATE - I received a different unit of the HP LP2475w today and I'm very happy with this one. I see none of the hue shift I noticed on the first unit. Also, the inputs are much more stable. It's great, as it is I wouldn't hesitate to recommend the screen. It calibrates well with my Eye-One Display2. Maybe HP need to tighten their quality control a bit, because the first one shouldn't have reached me. So if you bought one and aren't happy with it, have it replaced.

I must say the reseller where I bought the thing in The Netherlands, an online store called Central Point Europe, have been terrific. They sent me a brand new unit today on my promise that I would send back the first one tomorrow- and that after almost three weeks of testing on my part. I now have two. I don't even have to send it in, they're picking it up. Great service.

Gerard Kingma
www.kingma.nu
« Last Edit: November 27, 2008, 06:26:03 AM by GerardK » Logged
GerardK
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« Reply #18 on: November 27, 2008, 06:25:31 AM »
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SECOND UPDATE - For the record, initially I was enthusiastic about the second unit I received, but noticed later that instead of a hue shift from neutral to red on the right, this second unit had a hue shift from neutral to blueish on the left side of the screen. I found I couldn't get used to it and I've sent the HP LP 2475w back. I now have a Eizo CG222W which is much more uniform in colour. It's twice as expensive and it's less real estate in screen area, but I decided I'd rather have a smaller accurate screen than a bigger not-so-accuate screen.



Gerard Kingma
www.kingma.nu

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