Best LCD grading monitor on the planet [Archive]

GlennChan

08-09-2008, 07:31 PM

I think that DPX LCD panel is manufactured probably by Samsung or other huge producer and it`s same product as in thousand other monitors so therefore it display only 8 bits.
I think that it's 10-bit because that's the spec on the eCinema website. And there are other companies out there making 10-bit panels... the HP Dreamcolor being one.

2- There is no magic in the backlight in terms of bit depth / banding artifacts.

3- Dither does matter. Suppose you have a 4k and a 2k display... if they both use the same dithering technique (that's not truncation or simple rounding), then the 4k display will have better performance in terms of whether or not you see banding artifacts.

Why?
One easy, lazy way to think about it is this. As you move further away, you're less likely to see banding artifacts. The 4K display is like 4 2K displays that are positioned further away.

GlennChan

08-09-2008, 07:38 PM

Regarding IMLED displays...

What I've heard is something like this:
A potential problem with IMLED is that halos will appear if there is a white line on a black background. Suppose that a white line is over an area such that only one row of LEDs is lit. The LEDs will have to be at full intensity... the black level in that area will be the same as a normal LCD since the LED has not been modulated to be darker and therefore lower the black level. So you'll see a halo in that area.

What happens if the line is moved so that it's now exactly between two rows of LEDs? In this situation, TWO rows of LEDs will be lit. Because two rows of LEDs are now lit, then the halo will be larger in size. If this white line starts rotating, then these halos will start shifting all over as the line moves. (I would think of this as analogous to aliasing).

*I have never seen the Dolby display... but I've heard that this is why IMLED won't work for critical monitoring.

wesdonahue

08-26-2008, 01:44 PM

The HP DreamColor LCD monitor is, in fact, using an 8-bit LG panel that utilizes FRC (frame rate control) to dither out to 10-bits. What this means, of course, is that it is creating the illusion of all of the color shades outside its native 8-bit colorspace of 16.7 million colors by blending nearby shades to fool the eyes into perceiving other shades - in this case, over 1 billion other shades. It is indeed "dream" color. For reality color...well, that's where eCinema likes to play. If you'd like to know more, drop me a line.

Emery Wells

08-26-2008, 02:30 PM

I spoke to wes at e-cinema and they informed the DPX is in fact a true 10bit panel. The only other product to market using that panel is the BVML230. Of note, their Pro monitor will use the same 10bit panel, sans LED backlight.

Looking forward to seeing their DPX and Pro monitors when they come out.

Blair S. Paulsen

08-26-2008, 04:05 PM

I happen to own an eCinema DCM-23 which is a nice monitor but the blacks are nothing like the newer panels, particularly the DPX series unit I saw at NAB. I have a DreamColor sitting at my vendors shop awaiting a 10 bit HD-SDI to HDMI solution as I was under the impression that the DreamColor really was a 10 bit unit all the way to the panel. Assuming Wes is correct, then the 10 bit pipeline will simply improve the accuracy of the mathematical illusion he describes - that's probably valuable though not "true" 10 bit color.

The thread starter stipulated that money was no object, in which case the eCinema DPX unit would get my vote based on what I have seen. For those of us with more modest budgets I am hopeful that with the right interface and proper calibration the DreamColor will offer a viable LCD based grading option. YMMV.

Petr Dvorak

08-26-2008, 06:06 PM

mmm ... yep 10 bits is not easy to get.
Just wonder how many bits deliver Sony 4K and digital cinema projectors?

Definitely thanx for clearing things up

GlennChan

08-26-2008, 07:30 PM

You also have to take into account the transfer function of the display. So if the transfer function of the display and the ideal transfer function doesn't match, you'll have bit depth crowded into some tonal ranges and not in other tonal ranges.

Displays like DLP and plasma have a transfer function of 1. They will have some trouble for code values 1 above black level (unless the bit depth is really really high). So supposedly for plasmas, this will cause grainy looking blacks.

I haven't played with these display devices myself so I can't tell you how it works out. Some plasmas are driven at 12-bits with a transfer function of 1 (I believe).

2- Something you can try:
For many real world images, you can truncate it to 7 bits with no visual loss (e.g. Photoshop... levels down, levels up). Banding does become an issue when there are large flat areas of colors (or gradients), the monitor is larger / visual angle is larger, and when the source is noisefree.

Dither does cause implementations to vary in how well they do. The direction of a gradient may make a difference for the cheaper dither circuits out there.

Martin Euredjian

08-26-2008, 11:25 PM

LCD's have gone through so many marketing twists that it is hard to keep track of reality any more. Let's just say that consumer-land will never cease to amaze me.

The next two fads in consumer-land are "10 bit" and "120Hz", both in quotes because the level of veracity of the marketing claims is rarely very high.

In the case of the Dreamcolor display, as Wes has already clarified, it is, in fact, an 8 bit display with FRC-based dithering. We always jump on new technology, and this was no different. We contacted LG --who manufacture the panel for HP-- and quickly learned that it wasn't a real 10 bit panel but rather an 8 bit with built-in FRC. At that point we lost interest, as dithering and FRC can introduce innacuracies and artifacts that have no place in professional critical evaluation of images. To put it in camera terms, it is as though someone was taking a camera with an HD sensor and calling it a 4K camera because it has a built-in up-scaler. It might look OK, but it isn't the real deal.

What determines that a panel is 8 bits? LCDs are, at the pixel level, analog. Each and every column is, effectively, driven by the output of a digital to analog converter. If the DAC is an 8 bit DAC, the panel can only produce 256 shades per channel. If the DAC, in turn, is a 10 bit DAC, it is good for 1024 shades per channel (or over 1 billion colors) per pixel.

The distinction between the terms "dithering" and "FRC" can be confusing. Dithering involves moving the color of a pixel up and down near the desired perceived value in order to attempt to make the viewer see a different color. If you've ever seen a kid's top with black and white stripes spin fast enough that the black and white blend into gray, you are seeing a form of dithering. FRC takes this concept to a different level by taking clusters of pixels and manipulating them across multiple frames to acheive the same effect.

The primary issue with these methods is that they introduce color and temporal artifacts that were not in the source data in the first place. As motion, interlacing, pulldown and other video/motion-picture elements come into play, FRC and dithering interact with the image processing that came before the pixel and can produce unpredictable results. The bottom line is that if accuracy and repeatability are important, FRC and dithering are not desirable.

Where they might be useful is in a "preview" function. This is the case of wanting to have an idea of what something might look like in ten bits without the need for real 10 bit color. Not reference-grade, but perhaps acceptable.

The route we have taken is to use real 10 bits-at-the-pixel technology which can truly reproduce --without dithering or any other trickery-- any one of over one billion colors at every pixel. If it is about critical image evaluation, that's the only approach that works. What's involved at the panel level is the substitution of 8 bit column DACs with 10 bit chips. This isn't as easy as it may sound.

Of course, a true 10 bit panel can be dithered to 12 or even 14 bits for preview applications. So, if you start with real 10 bits you can fake higher bit depths for preview purposes.

-Martin Euredjian
eCinema Systems, Inc.

Emery Wells

08-28-2008, 06:28 AM

Martin, thank you for all this info. The topic of contrast ratio has always been slightly confusing and Im wondering if you could shed some light on the subject. Consumer land constantly touts wildly ridiculous contrast ratios but you'll often find terms like 'effective contrast ratio' in the fine print. What are the methods for effectively increasing contrast ratios and how do they differ from true contrast ratios?

How is the DPX able to achieve 15,000 to 1? Is it using local dimming?

Martin Euredjian

08-28-2008, 07:45 AM

While I can't discuss the technology behind the DPX's performance at this point I can certainly discuss contrast ratio specifications.

Yes, consumer-land is full of marketing twists to make things seem better than they really are. Few fields are as guilty of this as LCDs. What's going on is akin to car manufacturers quoting 150 miles per gallon with the fine print stating that this is on a 45 degree incline, with bicycle tires, on an ice-covered road, drafting a truck three feet in front, the wind behind you and only one cylinder working. Neat trick, but it isn't real and nobody is going to drive a car that way.

Contrast ratio: A measurement that describes the relative luminance between the black and white points of a monitor (or projector, etc.). Saying that the contrast ratio is 10 means that black is ten times darker than whatever white happens to be set to.

The ratio can be different depending on how the measurements are taken.

Sequential contrast:
-----------------------------------------------------------------
1- Calibrate the monitor as it will be used.
2- Send a full frame of white to the monitor
3- Measure white
4- Now switch to black
5- Measure black
6- Contrast ratio = white luminance / black luminance

Typical sequential ratios:
BVM CRT: 15,000 to 1
DPX LCD: 15,000 to 1
Typical LCD: 500~1,000 to 1

Simultaneous contrast:
-----------------------------------------------------------------
1- Calibrate the monitor as it will be used.
2- Send a black and white checkerboard pattern to monitor
3- Measure white square near center
4- Measure black square near center
5- Contrast ratio = white luminance / black luminance

Typical simultaneous ratios:
BVM CRT: 280 to 1 (primarily due to flare in glass)
DPX LCD: 15,000 to 1
Typical LCD: 500~1,000 to 1

Consumer contrast:
-----------------------------------------------------------------
1- Don't calibrate the monitor as it will be used in the real world
2- Crank up the brightness, backlight and anything you can to make it super-bright
3- Send white to the monitor
4- Measure white
5- Now crank everything down as far as it will go. Make it super-dark to the point that the image might not even be usable.
6- Send it black
7- Measure black
8- Contrast ratio = white luminance / black luminance

Typical simultaneous ratios:
Moderate marketing spin: 3,000 to 1
The really good marketing guys: 30,000 to 1
The "our customers are stupid" guys: 1,000,000 to 1

The intent behind Sequential contrast is to determine the absolute best performance for a fully calibrated monitor in proper operating conditions. It is relevant for such things as titles over black or very dark scenery, where deep dark blacks are a necessity.

Simultaneous contrast is there to give you an idea of how well the contrast performance holds-up as varied image content occupies different portions of the screen. CRTs are variable contrast devices. As content becomes more complex contrast is reduced. This can be looked as as MTF (Modulation Trasfer Function) just as you might with camera lenses.

Consumer contrast figures are there to deceive and market based on the idea that consumers don't understand any of this and they can be easily impressed by big names quoting big numbers. Not much can be said about this other than I hope that some degree of regulation is applied to the industry in order to protect consumers at some point.

-Martin

Greg M

08-28-2008, 08:21 AM

has anyone compared the mid level ecinema displays to the Cine-tal?

GlennChan

08-28-2008, 01:17 PM

The Editor's Lounge did a shootout of various monitors but Cinetal wasn't in attendance.
http://tinyurl.com/5lv6ql - Cow thread
http://movies.groups.yahoo.com/group/Avid-L2/message/40768 - Avid L2 thread

IMO... the price/performance of the mid-end monitors right now isn't really compelling. None of them do real black (contrast ratio of the Cinetal is 1000:1 I was told). And they don't look significantly better than the cheaper stuff. Meanwhile, the monitor will depreciate like crazy when better stuff comes out.
If eCinema's competitors figure out their tricks then we'd have more LCDs doing real black. FED and OLED are also on the horizon (though the FED folks haven't gotten financing for a factory yet... might be vapourware even though the technology looks good).

Larger monitors are also coming out (e.g. 40"). Clients will likely be more impressed by a 40" monitor than a smaller monitor, whereas they probably won't spot a difference between some of these mid-range monitors and a $4K monitor.

I saw the JVC 24", Cinetal, BVM-L230 (and 40" BVM-L), Barco RHDM at NAB. Not the greatest place to look at monitors, but there wasn't a striking difference between any of them (except that the Barco flickers slightly because of the backlight scanning). I also saw a 40" model by eCinema (FX40??).
From a business perspective, there are successful post houses out there with crappy monitoring. They've spent five figures for a BVM CRT but they didn't even bother to get proper lighting (i.e. not tungsten) or arrange the lighting so that the light doesn't cause glare on the face of the monitor.
So to me, it seems that your best business decision would be to either:
A- Go cheap and get the JVC 24" DT and make the surround bright. And get nice furniture.
B- Get a large monitor and make the surround bright to hide the black level.
C- Get a monitor that does good blacks. Or wait until there are more choices in that area.
The difference between the DPX and a CRT isn't subtle (the DPX doesn't flare); though you might need to point that out to people; the difference is easier to spot than the difference between 4K and 2K. I can't tell you if the monitor might have obscure flaws in certain situations... get a demo unit and check for yourself.

John Tissavary

09-20-2008, 02:17 AM

In the case of the Dreamcolor display, as Wes has already clarified, it is, in fact, an 8 bit display with FRC-based dithering. We always jump on new technology, and this was no different. We contacted LG --who manufacture the panel for HP-- and quickly learned that it wasn't a real 10 bit panel but rather an 8 bit with built-in FRC. At that point we lost interest, as dithering and FRC can introduce innacuracies and artifacts that have no place in professional critical evaluation of images.

Martin, are you saying that HP is blatantly lying in their literature and client communications when they specifically say that there is no dithering and no FRC in their 10bit panel? Here's a quote from page 5 of THIS FAQ (http://h20219.www2.hp.com/Hpsub/downloads/DreamColor_and_LP2480zx_FAQ_June08a.pdf) on the HP website:

"A full 30bit pixel is sent from the DreamColor Engine to be displayed on the HP 30-bit LCD panel with no dithering or frame rate control."

This is a specific and opposite claim to the one you are making. I would be grateful for any clarification at all.

Regards,

John T.

Tony Lorentzen

10-01-2008, 04:39 PM

And then... silence. Any reason you haven't responded to Johns question, Martin?

GlennChan

10-01-2008, 05:21 PM

He could be busy running his company (and any other number of reasons). If you'd like an answer, you could try emailing him through the email listed on their website.

http://www.ecinemasystems.com/contact.html

Jean Déraps

10-13-2008, 07:10 PM

Has anyone come up with the strait facts concerning the DreamColor?

BTW here's a link to that FAQ from HP

http://h20202.www2.hp.com/Hpsub/downloads/DreamColor_and_LP2480zx_FAQ_June08a.pdf

Alexander Christ

10-14-2008, 09:23 AM

I contacted HP Switzerland and they told me the display is true 10-bit.

fde101

10-14-2008, 09:57 AM

"A full 30bit pixel is sent from the DreamColor Engine to be displayed on the HP 30-bit LCD panel with no dithering or frame rate control."

I know next to nothing about this, but let me show one possible reinterpretation of this statement to clarify the complexity of this question:

We send a 30-bit pixel value from the DreamColor Engine to the 30-bit LCD panel hardware, which does its own dithering and displays on a panel physically capable of showing a 24-bit color.

Again, I don't know this, I'm merely pointing out that the concept is not incompatible with the statement...

Petr Dvorak

10-14-2008, 07:30 PM

Yep I think that whatever-bit value is sent to whatever engine but LCD can only physicaly diplays 8 bits. Same old story

There is some older Eizo panel where they said that it "works" with 10 bit colors, but works DOESN'T mean displays ... yep marketing

Joseph Ward

10-15-2008, 11:00 AM

What about Apple LED Cinema Display?

http://store.apple.com/us/product/MB382?mco=MTkzODk0Mg

Michael Lindsay

10-26-2008, 12:11 PM

Martin, are you saying that HP is blatantly lying in their literature and client communications when they specifically say that there is no dithering and no FRC in their 10bit panel? Here's a quote from page 5 of THIS FAQ (http://h20219.www2.hp.com/Hpsub/downloads/DreamColor_and_LP2480zx_FAQ_June08a.pdf) on the HP website:

"A full 30bit pixel is sent from the DreamColor Engine to be displayed on the HP 30-bit LCD panel with no dithering or frame rate control."

This is a specific and opposite claim to the one you are making. I would be grateful for any clarification at all.

Regards,

John T.

Martin... care to comment?

regards

Michael

Steve Sherrick

10-26-2008, 09:40 PM

If in fact that's true about the HP display (I've never used one, so I'll take Martin's word until proven otherwise), it's similar to what TV Logic does. They use an 8 bit display and are dithering the 10 bit input. It looks good, but as Martin says having that full 10 bit path is the way to go because it removes some variables.

I look forward to the day when we have displays that are able to produce true black with precise color accuracy, easy calibration, and are affordable. I wish I could afford the E-Cinemas or these other high end monitors but it's not a reality right now.

Jean Déraps

11-04-2008, 08:26 AM

Here's an excerpt from the HP Dreamcolor user manual (my emphasis) :

10 bits/color LCD Module
As noted earlier, the LCD module in the LP2480zx monitor provides a 10 bits/color (30 bits/pixel) input,
with true 10-bit drivers within the LCD itself. This means that each primary (red, green, and blue) may
be controlled over 1,024 steps (input codes 0 to 1023) from the black level to the white (peak luminance
for that color). This results in over 1.07 billion separate colors available within the display’s gamut, versus
approximately 16.7 million for a conventional 8 bits/color display.

GlennChan

11-04-2008, 12:30 PM

Apparently the cheaper HP dreamcolor display (not the 2480zx) has an 8-bit panel.

I suppose somebody could test the 2480zx to see if it has an 8-bit or 10-bit panel??? (Though you'd have to figure out how to drive the panel at 10 bits.)

Jeff Kilgroe

11-04-2008, 12:53 PM

Apparently the cheaper HP dreamcolor display (not the 2480zx) has an 8-bit panel.

And which cheaper display would that be? The 2480zx is the only Dreamcolor display available right now.

IMO, HP should be hyping up their RGB backlight system on this display. It's great! The display is 10bits/channel internally and combined with their proprietary backlight system, they're driving that 8bit LG panel to new heights.

Seriously, for a $2400 display, I'm quite impressed. I was skeptical at first of HP's marketing and when the panel was confirmed to be an 8bit LG... But after seeing the monitor with my own eyes, I'm really liking it. I only wish it came in a 30" model! All in due time, I suppose.

Anyway, it's hands down the best 24" LCD display on the market under $10K. The upcoming models from EIZO, eCinema and others look like they will be much better, but at a much, much higher price tag.

For actual color grading, I don't think I would choose a 24" display of any type. I would go for a DLP projector or perhaps a large plasma screen like the Panasonic pro series w/ SDI option.

GlennChan

11-04-2008, 02:03 PM

This guy:
http://h10010.www1.hp.com/wwpc/us/en/sm/WF05a/382087-382087-64283-72270-444767-3648442.html

apparently it's not marketed under dreamcolor anymore.

Anyway, it's hands down the best 24" LCD display on the market under $10K. The upcoming models from EIZO, eCinema and others look like they will be much better, but at a much, much higher price tag.
I'd disagree with that. You can get a good 1920x1080/1200 HD-SDI monitor for <$4k. If you need to work with VTRs then it's a no brainer to get a HD-SDI monitor.

And HD-SDI is what I'd prefer so there's nothing wacky going on with video overlays and such. The wide gamut capability is somewhat of a bad thing for most users if you work solely with a Rec. 709 video workflow.
In the under $10k category, I believe you can get 40" 10-bit monitors with HD-SDI (e.g. ecinema fx40 is $6k now).

2- Somehow, HP got people to be way more excited about this monitor than other similar products.
If you look at computer monitors (e.g. no SDI input), you used to have lots of good choices in CRTs. And they were relatively cheaper (granted, CRTs are heavy!! and somewhat soft + hide noise and image defects).

Jeff Kilgroe

11-04-2008, 02:25 PM

Yes, plenty of great options in the <$10K range. But I was saying as far as 24" LCD monitors go. IMO, of the 22~24" LCD monitors on the market now, even compared to "studio" monitors with HD-SDI input, this DreamColor display looks really good. To me, it look a lot better than the LCD broadcast monitors from Panasonic, which are a big favorite for people looking in the <$5K range.

Personally, for color grading, I would choose something with an HD-SDI input just because of software / hardware support and compatibility.

Steve Sherrick

11-04-2008, 04:11 PM

I'm confused about the HP monitor. Is it an 8 bit panel or 10 bit? If it's just handling the 10 bit signal, processing it internally, and displaying on an 8-bit panel, well, my TV Logic does that too. If it's going to be 10 bit, it's got to be the whole way from 10 bit input to 10 bit display. Maybe I'm missing something here.

GlennChan

11-04-2008, 06:13 PM

Heh, I guess the mystery continues?

Jean Déraps

11-04-2008, 09:20 PM

Jeff, I'd like to know how you know it's an "8bit LG" panel... the HP User Guide states:

"As noted earlier, the LCD module in the LP2480zx monitor provides a 10 bits/color (30 bits/pixel) input, with true 10-bit drivers within the LCD itself."

Patrick Tresch

11-05-2008, 01:18 PM

Jeff, I'd like to know how you know it's an "8bit LG" panel...

Heehehe :biggrin:

Jeff, you should start a HP Dreamcolor thread! :)

Patrick

(second time Jeff is asked this exact questions)

GlennChan

11-24-2008, 08:28 PM

http://www.hardforum.com/showthread.php?t=1366545

An extensive forum post on the Dreamcolor monitor. Apparently there are very visible dithering artifacts, so so much for the whole 10-bit thing. (Turning off the dreamcolor engine would get rid of the dithering, but then the colors wouldn't be accurate.)

2- Also, the Dreamcolor engine is not enabled for interlaced sources and "YUV" (Y'CbCr) sources.

From http://www.justechn.com/2008/06/10/hp-dreamcolor-lp2480zx-lcd-display

Sean,
I wrote HP about your problem and I just got an email back from one of their engineers. Here is what he had to say:

I am a engineer working on the LP2480zx monitor. Sorry to hear that you are having difficulty getting the results that you would like from the HP DreamColor monitor. I was forwarded your post below describing your SDI setup. First of all let me assure you that the issues you described do not indicate anything wrong with the monitor.

* The DreamColor Engine is only enabled if the input is:
o Progressive (not interlaced) AND
o RGB (not YUV)
* If the input signal is Interlaced OR YUV, then the DreamColor Engine is disabled and there is no color management (the colors are unmanaged, reverts to Full (Native) gamut and the color presets menu is grayed out).
* With an SDI input, you must use an adapter that converts to progressive RGB at the output.
* The only adapter we have found that does this is the Gefen EXTHDSDI2DVISP HDSDI to HDMI adapter.

I am not sure which product you are using to convert the SDI signal to HDMI, but if it offers the option, please set it to convert the Yuv signal to RGB, and make sure that the output is non-interlaced.

If you don’t have those options we recommend the Gefen SDI to HDMI converter. Make sure that it has the most recent firmware. Then follow the adjustments below to make sure that the black level is set correctly

Emery Wells

11-24-2008, 08:37 PM

P.S. I spoke to Wes at ecinema today and their new DPX and Pro displays should be shipping sometime in january ($8k for the Pro, $12k for the Pro with dual link, and $40k for the DPX). They will also be offering a DVI version of their pro display to use as a GUI monitor along side a new 'finger printing' calibration system to sync them both up perfectly.

Jean Déraps

11-24-2008, 09:28 PM

Glen,
Mr. ToastyX brings up some valid points, but some of his points are subjective (like "sRGB still doesn't look right to me."). On my Dreamcolor I see some dithering artifacts in the REC 601 colourspace but don't seem to see any in the REC 709 (maybe my eyes are just tired). Of course, there shouldn't be any dithering in any colourspace, so I'll be looking into that with HP and my reseller.

Jeff Kilgroe

11-24-2008, 10:36 PM

I've worked with the DreamColor display a couple times now and almost bought one. I would buy one if I could get it in a 30" 2560x1600 size...

But I have to say that the above article is pretty much spot-on. The Dreamcolor engine is not available in all modes and yes, there is visible dithering to approximate all those colors on, what is still in reality, an 8bit display panel. However, the dithering is handled well and the monitor performs admirably for its relatively low price. For a budget grading solution, this is a very good option, provided you have the means to properly calibrate it.

Of course, there shouldn't be any dithering in any colourspace, so I'll be looking into that with HP and my reseller.

Dithering or banding, take your pick.. The panel in use can't display all the colors produced by the monitor's internal 30bit processing. There's a whitepaper from HP floating around out there that sheds some light on the dithering algorithm used, but I'm not sure where it's at off the top of my head. I seem to recall that it may have been linked to in one of the threads on these forums about the dreamcolor.

GlennChan

11-25-2008, 12:59 AM

subjective (like "sRGB still doesn't look right to me.")
Have you compared the dreamcolor to a broadcast CRT? Do the colors look right?

I think that a lot of the time the theory is wrong or doesn't capture all the complexities of human vision... I wouldn't immediately dismiss subjective comments because they are subjective (especially since human perception is a subjective thing).

Steve Sherrick

11-25-2008, 10:22 AM

So, they're doing what TV Logic is doing. High quality dithering of 10 bit inputs to achieve an accurate picture on an 8bit display. Looking forward to the day when we can see highly precise modern display technology that doesn't have to rely on trickery. Lots of variables though that make this easier said than done.

Jean Déraps

12-01-2008, 10:12 PM

No Glen, I haven't compared the DreamColor to a CRT broadcast, but then again, I wasn't the one doing the review/testing. That comment ("sRGB still doesn't look right to me") wasn't the only thing that I found to be subjective either. By the way, I do have a DreamColor monitor.

Dan Bennett, from HP, has replied to one of my questions on one of the forums over at creative cow and has provided much interesting information concerning this display (see the color forum).

Note: I tried to enter the link, but it kept getting changed to something completely different, for some strange reason.

Curran Giddens

12-02-2008, 06:49 AM

Note: I tried to enter the link, but it kept getting changed to something completely different, for some strange reason.

Links to Creative Cow is not allowed. Next time you will be banned! ha ha. just kidding

I was kind of hoping Dan Bennett would answer your question about whether the panel is 8 or 10 bits. I still haven't seen any proof, and I'm not going to take my monitor apart to find out. :detective2:

Jean Déraps

12-02-2008, 07:53 AM

But he does clearly state the following:
"* A true 30-bit panel (despite rumors to the contrary!) which allows the HP DreamColor Engine to map input colors to a true palette of 1.07 billion physically displayable colors. This reduces color error when performing the color and tone mapping."

And this is after stating that the DreamColor engine is 36 bits.

I just hope he'll explain how we can get the best rendering without dithering.

GlennChan

12-02-2008, 01:48 PM

Note: I tried to enter the link, but it kept getting changed to something completely different, for some strange reason.
It's a long story (possibly because some people were unhappy about cow's past censorship/anti-competition policies). The short answer is to use tinyurl.com on your links.

GlennChan

12-02-2008, 02:38 PM

I purchased the monitor on the basis of what I read in HP marketing materials
Nooooooooooooooo.... lol. I think there's a danger in purchasing anything expensive based on marketing materials... products tend to differ significantly from what is advertised.

2- What is the point of having a 10-bit panel if the end result is that the image has visible dithering artifacts? (Granted, I have not seen this for myself.) In theory, the image ought to be good... in practice, it doesn't look like this is the case.

To quote the HP employee:

2 - 10-bit pixels (when you get that 10-bit graphics card!) are passed straight through to the panel; at least in "Full" mode. Of course, in a color managed mode such as Rec 709, there'll be some reduction of the monitor's native color space to map onto the Rec 709 color space, which means that not all 1.07 billion colors are available. It's hard to say what the real number is, but if you imagine, say, 800-900 million it wouldn't be too far off. Still much better than an 8-bit panel. :-)
A 10-bit Rec. 709 signal actually doesn't have 800-900 million colors to begin with. There is significant waste because the Y'CbCr color space defines many out-of-gamut and illegal colors, including values that call for negative light (which doesn't exist / is an impossible color).

Or looking at it from the monitor's point of view, I believe that significantly less than 800 million colors that the monitor can reproduce would be used for a Rec. 709 image. (Here it's about the relative areas of the color gamuts, rec. 709 versus the monitor's maximum gamut. Too lazy to calculate it, but the wider the gamut of the monitor is... the more thinly spread out its bits are and therefore less of those bits are relevant to displaying a Rec. 709 image.)
In practice it probably doesn't matter, but I would point out that this is likely a case of technical BS.

And this is after stating that the DreamColor engine is 36 bits.
You can think of it as bottlenecks... usually, the bottleneck in terms of bit depth is in the panel of the monitor. The various parts of the monitor have different bit depths.

--e.g. the input can be 8-bit, 10-bit, etc. RGB versus Y'CbCr makes a difference, as you can get rounding error converting between the two. Same deal with full-scale RGB versus studio video-scaled RGB. Apparently the Dreamcolor can't take YUV signals, so you'd need to convert that to RGB (likely losing some bits in the process).

--The monitor has some internal processing. 32-bit floating point precision per channel would not be unreasonable (so that would be 3 channels X 32-bit). If you want to do things correctly, you need to do linear light processing... this takes a lot of bit depth. You may be able to approximate the calculations well enough with a 3-D LUT with 12-bit depth... that I don't know.

Or if the monitor naturally had a Rec. 709 gamut, then you wouldn't need to do linear light processing.

--The panel itself has a certain bit depth. Because the transfer function of the display is far off the from the ideal transfer function (that of a CRT, in the case of broadcast) then the bit depth is spread thinly for some parts of the tonal range.
This is a bigger problem for plasmas and DLPs, since their transfer function is linear and requires major work. e.g. A 10-bit plasma panel is not good enough for professional work... shadows will have noisy dither artifacts.

--The display might also lose some available bits after calibration, e.g. if setting the white point is done digitally. (This can also be done by varying RGB LED backlighting... but then I think you have to stabilize the LEDs.)

Or, you take the simple approach... and see if the end results are good. Can you see banding or dither-related artifacts?

Jason Diamond

12-03-2008, 09:31 AM

http://www.hardforum.com/showthread.php?t=1366545

here is a great review in depth with pics and all, detailing the ins and outs of the HP dreamcolor.

Andrae Palmer

01-28-2009, 04:21 PM

So still no definite answer if the HP dreamworks panel is 8 bits or 10 bits? All this marketing lingo is confusing. Dan Bennet a HP DreamColor Tech reported that its a true 30 bit:

http://forums.http://www.teenink.com/Past/2002/January/CollegeEssays/IHateCows.html.net/thread/223/7928#7953

If this is the case where is the dithering coming from?

BTW... I thank all the previous posters for the very helpful technical clarifications.

GlennChan

01-29-2009, 09:59 PM

Don't link to creativecow because that won't work. use tinyURL to get around it:
http://tinyurl.com/cplsnn

Andrae Palmer

01-30-2009, 09:13 AM

Don't link to http://www.teenink.com/Past/2002/January/CollegeEssays/IHateCows.html because that won't work. use tinyURL to get around it:
http://tinyurl.com/cplsnn

Thanks... didn't realize the link was such a garbled mess.

Dan Graetz

01-31-2009, 04:29 PM

I've just relocated my studio and I'm looking into a ceiling mounted projector for grading. I'm currently using the JVC 24" DT (which I plan to keep as an extra reference). I'm hoping to spend $US10-15k. So far the front-runner is the new JVC RS20 (http://pro.jvc.com/prof/attributes/features.jsp?model_id=MDL101823) (also sold in other countries as HD750). They're marketing it as a 'reference' projector. It's supposedly THX certified (from what I understand you get a preset color profile that's been calibrated to THX standards). It's 1080p, 50,000:1 contrast ratio & 900 lumens. Should be perfect in terms of brightness for the size of room I'm setting up (20' x 20').

Keen for any thoughts on the viability of this for grading. I'm running Apple Color with an Eclipse CX console through a Kona 3. The proj takes HDMI 1.3 so I was either going to use a Blackmagic converter to go from HD-SDI to HDMI (which I've used with some success on a Bravia), or possible JVC's external video processor (http://pro.jvc.com/prof/attributes/features.jsp?model_id=MDL101766) which is upgradeable to HD-SDI.

The other interesting option is a motorised anamorphic lens to go in front. JVC sell it as an RSAL1 (http://pro.jvc.com/prof/attributes/features.jsp?model_id=MDL101744) but it's really a re-badged Panamorph UH480 (http://www.panamorph.com/Products.html). These are mostly designed to enlarge 2.35:1 content that's letterboxed within 16:9 - to fill a native 2.35 screen. Could be useful when editing RED 2:1 footage which through the Kona3 gets letterboxed inside 1080p24. The RS20 has a trigger output which can automate the anamorphic lens moving into place when a certain mode is selected. Could possibly come into play with RED footage that has been shot ANA - not sure yet whether it can stretch that far.

As far as a screen goes it seems that simple matte white is the most color accurate option - with some kind of black velour trim to improve visibility. High gain reflective screens apparently affect color reproduction and viewing angle.

Any suggestions would be appreciated. Obviously if I could pony up for a 2k or even the new JVC 4k (or even better - Meridian's modded JVC 4k - the 810) I would. But this is sort of an interim solution while I finish the edit and grade on the feature (http://www.reduser.net/forum/showthread.php?t=25306) I'm currently working on.

Thanks in advance,
Dan

Evin Grant

01-31-2009, 05:12 PM

We have a clibrated JVC DLA RS-1 in our Baselight suite...
http://www.4kninjas.net/dojo/index.php
http://www.coregroupltd.com/Core_Group_Ltd..html
It rocks!

M Most

01-31-2009, 05:52 PM

We have a clibrated JVC DLA RS-1 in our Baselight suite...

I'm curious:

What exactly is the projector calibrated to? This particular projector is a high end consumer unit, so it does not have internal lookup tables and the ability to do color space conversions - in other words, it is what it is. So if one is looking for accuracy to a particular specification for professional use, the only way to achieve that is through visual emulation provided by creating a 3D LUT after performing a profile on the projector once you've done a basic setup based on test charts. Is that basically what you mean by "calibrated"?

There are a lot of high end consumer projectors that "look nice." But for professional use, it's about accuracy, adherence to a standard. Looking good is not necessarily what one is after.

Dan Graetz

01-31-2009, 06:25 PM

The new JVCs are CMS capable and have custom gamma options. The CMS controls wouldn't be anything near what a Barco or similar would have - but it's enough to get it close enough.

I spent a few hours trolling through posts on avsforum where all the home theater videophiles hang out. They're into some pretty hardcore calibration - way over and above any of the broadcast calibration tips I've found so far. They use color probes like the GreTagMacbeth units, in combination with custom test patterns etc.

The JVCs are inherently Rec.709 so I'm not sure if that will limit options for log grading RED footage?

Allan Stallard

01-31-2009, 06:43 PM

Concerning the HP Dreamcolor if you look deeper on the interweb , concerning the dithering, it was discussed that it had been resolved with firmware updates a while ago. An associate of mine bought one after reading all the hubbabaloo and decided to go for it. It's seen lots of 4K r3d files and shows no signs of dithering.

Just trying to help. I'm buying one myself in a couple weeks.

I also know that you wouldn't be alone in grading with one and I have heard that anyone who has one loves it.

Oh yeah, it doesn't cost 10k. My friend bought one for 2K.

So if price is a consideration...

Andrae Palmer

01-31-2009, 07:38 PM

Allan,

Thanks for the update. So it is a true 30 bit display after all.

Curran Giddens

02-01-2009, 06:51 AM

Concerning the HP Dreamcolor if you look deeper on the interweb , concerning the dithering, it was discussed that it had been resolved with firmware updates a while ago.

http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=382087&prodSeriesId=3648397&swItem=vc-64736-1&prodNameId=3648398&swEnvOID=1093&swLang=13&taskId=135&mode=4&idx=0

Yeah, Firmware version TR133.SL063.BL167 Rev. A (1 Oct 2008) fixes the problem. You will need to run the firmware update with Windows.

Allan Stallard

02-01-2009, 08:21 AM

Allan,

Thanks for the update. So it is a true 30 bit display after all.

Well, I wouldn't say myself how many bits it is. I'm saying the dithering issue has been resolved.. in example the post above.

M Most

02-01-2009, 08:23 AM

The new JVCs are CMS capable and have custom gamma options. The CMS controls wouldn't be anything near what a Barco or similar would have - but it's enough to get it close enough.

If you are talking about the RS20, that would be true. For the RS1, it isn't.

Michael Lindsay

02-01-2009, 08:47 AM

Hi

Our BVM-D (HD CRT sony) is getting a little long in the tooth... what would be fantastic is a group buy on Barco's RHDM-2301. I suspect they will not be priced for a 'Red like' sales numbers. So maybe the price could be adjusted through high sales numbers?

Even the Sony 23" revison would be interesting...

Any thoughts?

Michael L

GlennChan

02-01-2009, 10:54 AM

I'm not that impressed by the RHDM-2301 and the Sony BVM-L230... they don't look significantly better than other monitors a fraction of their cost (e.g. eCinema FX, JVC's 24" DT). The high-priced LCDs still suffer from limited blacks... you can't have good color if the blacks are raised.

Whereas there are other monitors that will come out (or are currently shipping?) that will be noticeably better than the Barco and Sony BVM-L230. eCinema's DPX monitor does the best blacks I have ever seen; field emission technologies is building a plant (their prototype looked good... we'll see what they ship). Or right now you should be able to get a ~40" monitor... clients will definitely see the difference between that and a smaller monitor.

2- If anything, eCinema looks like they have the most Red-like pricing.

As far as clients go, their 40" monitor ($6k) would likely look better than Sony's or Barco's >$20k+ 23" monitors. The top 40" panels also have a slightly better contrast ratio than the top smaller panels.

*Do your own homework and demo monitors before buying them to check for any weird artifacts or defects.